Publications

2016

Chiu, J.H.C.; Kim, G.A.; Daniels, R.; Takayama, S.; “3 Electrochemical Sensors for Organs-on-a-Chip.” Book Chapter in Regenerative Medicine Technology: On-a-Chip Applications for Disease Modeling, Drug Discovery and Personalized Medicine. 2016. Editors S.V. Mutphy, and A. Atalia

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An in vitro analytical system capable of accurate representation of in vivo physiological states for the purpose of medical diagnostics is the goal of human-on-a-chip–based technology. Microfluidics provides the platform on which this goal can be achieved. Future human-on-a-chip platforms may utilize microfluidic electrochemical sensors for oxygen, carbon dioxide, glucose, and a number of other vital biochemicals. This chapter outlines the design and application of these technologies.

 

Han, M.; Kim, B.C.; Matsuoka, T.; Thouless, M.D.; Takayama, S.; ”
Dynamic simulations show repeated narrowing maximizes DNA linearization in elastomeric nanochannels.” Biomicrofluidics. 2016. DOI: 10.1063/1.4967963.

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This paper uses computer simulations to reveal unprecedented details about linearization of deoxyribonucleic acid (DNA) inside dynamic nanochannels that can be repeatedly widened and narrowed. Two phenomena that induce linearization during channel narrowing, elongational-flow and confinement, occur simultaneously, regardless of narrowing speed. Repeated narrowing and widening, something uniquely enabled by the elastomeric nanochannels, significantly decrease the time to reach the equilibrium-level of stretch when performed within periods comparable to the chain relaxation time and more effectively untangle chains into more linearized biopolymers.

 

Sumit, M.; Takayama, S.; Linderman, J.J.; “New insights into mammalian signaling pathways using microfluidic pulsatile inputs and mathematical modeling.” Integr.Biol. 2016. DOI: 10.1039/C6IB00178E.

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Temporally modulated input mimics physiology. This chemical communication strategy filters the biochemical noise through entrainment and phase-locking. A combined approach involving microfluidic pulsatile stimulation and mathematical modeling has led to deciphering of hidden/unknown temporal motifs in several mammalian signaling pathways and has provided mechanistic insights, including how these motifs combine to form distinct band-pass filters and govern fate regulation under dynamic microenvironment. This approach can be utilized to understand signaling circuit architectures and to gain mechanistic insights for several other signaling systems.

 

Eiden, L.; Yamanashi, C.; Takayama, S.; Dishinger, J.F.; “Aqueous two-phase system rehydration of antibody-polymer microarrays enables convenient compartmentalized multiplex immunoassays.” Anal.Chem. 2016. DOI: 10.1021/acs.analchem.6b02960.

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A major weakness inherent to multiplex enzyme-linked immunosorbent assays (ELISA) is generation of false signals through reagent-driven crosstalk. Here, we report an improved, user-friendly, crosstalk-free multiplex ELISA method in which dehydrated arrays of co-localized capture and detection antibodies in DEX are prepared on multiwell plates. Addition of a PEG-based sample buffer rehydrates antibody/DEX droplets for analysis. In this report, we demonstrate rehydrated ATPS components for multiplex ELISA retain the ability to compartmentalize antibodies and prevent crosstalk, while analytes in sample buffer partition into rehydrated DEX droplets for analysis. Utility of this method was demonstrated through quantitative analysis of five inflammatory cytokines in lipopolysaccharide-stimulated ThP-1 cell culture supernatant.

 

Ramamurthy, P.; White, J.B.; Park, J.Y.; Hume, R.I.; Ebisu, F.; Mendez, F.; Takayama, S.; Barald, K.F.; “Concomitant differentiation of a population of mouse embryonic stem cells into neuron-like cells and Schwann cell-like cells in a slow-flow microfluidic device.” Dev.Dynam. 2016. DOI: 10.1002/dvdy.24466.

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To send meaningful information to the brain, an inner ear cochlear implant (CI) must become closely coupled to as large and healthy a population of remaining Spiral Ganglion Neurons (SGN) as possible. Inner ear gangliogenesis depends on macrophage migration inhibitory factor (MIF), a directionally attractant neurotrophic cytokine made by both Schwann and supporting cells. MIF-induced mouse embryonic stem cell (mESC)-derived “neurons” could potentially substitute for lost or damaged SGN. mESC-derived “Schwann cells” produce MIF as do all Schwann cells and could attract SGN to “cell coated” implant. Two novel stem cell-based approaches for treating the problem of sensorineural hearing loss are described.

 

Kim, S.J.; Zhu, X.; Takayama, S.; “Gravity-Driven Fluid Pumping and Cell Manipulation.” Book Chapter in Microtechnology for Cell Manipulation and Sorting. 2016. Editors W Lee, P Tseng, and D Di Carlo

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Microfluidic systems require fluid pumping. Here, we describe microfluidic devices that utilize gravity—which is free, steady, and ubiquitous on earth—as a driving force for generation of constant fluid flow as well as periodically switching flows. We also describe applications of such devices. Gravity driven steady flow devices are described that enable microfluidic sperm sorting based on mobility and for cell culture where cells within different regions of a channel are treated with different concentrations of chemicals to analyze gradient responses. Gravity-driven fluidic oscillator devices are also described where a single device enabled the screening of the effect of three different shear stresses at four different frequencies (12 shearing conditions total) to reveal that there is an optimal frequency that endothelial cells respond to in terms of cell shape change.

 

Kojima, T.; Hirai, K.; Zhou, Y.; Weerappuli, P.; Takayama, S.; Kotov, N.A.; “Shrinking Microdroplets in Oil Assist Metamorphoses of Nanoparticle Assemblies.” Langmiur. 2016. DOI: 10.1021/acs.langmuir.6b01960.

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While most techniques for controlling NP assembly have focused upon altering particle properties in static bulk solutions, the alternation of micro-scale assembly environment serves as an alternative method to reconfigure NP assembly. Here we report and characterize the spontaneous assembly of CdTe NPs within an aqueous microdroplet suspended in oil. Single droplet of NPs aqueous dispersion was suspended at an oil-oil interface. The gradual diffusion of the aqueous solution into the surrounding oil medium results in an overall shrinking of the microdroplet, and a concomitant agglomeration of CdTe NPs at the droplet interface into branched assemblies that evolve in size from ~50 µm to ~1000 µm. Here, the fractal dimension of NP assemblies increases from ~1.7 to ~1.9 through dentritic evolution. Owing to the high surface-to-volume ratio of the microdroplet, constituents of the soybean oil may enter the aqueous solution across the microdroplet interface and contribute toward determining the terminal dentritic structure of NP assembly.

 

Cavnar, S.P.; Xiao, A.; Gibbons, A.E.; Rickelmann, A.D.; Neely, T.; Luker, K.E.; Takayama, S.; Luker, G.D.; “Imaging Sensitivity of Quiescent Cancer Cells to Metabolic Perturbations in Bone Marrow Spheroids.” Tomography. 2016. DOI: 10.18383/j.tom.2016.00157.

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Malignant cells from breast cancer and other common cancers such as prostate and melanoma may persist in bone marrow as quiescent, non-dividing cells that remain viable for years or even decades before resuming proliferation to cause recurrent disease. This phenomenon, referred to clinically as tumor dormancy, poses tremendous challenges to curing patients with breast cancer. We recently developed a 3D spheroid model of quiescent breast cancer cells in bone marrow for mechanistic and drug testing studies. We combined this model with optical imaging methods for label-free detection of cells preferentially utilizing glycolysis versus oxidative metabolism to investigate the metabolic state of co-culture spheroids with different bone marrow stromal and breast cancer cells. These studies establish an integrated imaging approach to analyze metabolism in complex tissue environments to identify new metabolically-targeted cancer therapies.

 

Yerelda, N.; Kojima, T.; Yang, Y.; Takayama, S.; Kanapathipillai, M.; “Aqueous Two Phase System Assisted Self-Assembled PLGA Microparticles.” Sci Rep. 2016. DOI: 10.1038/srep27736.

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Here, we produce poly(lactide-co-glycolide) (PLGA) based microparticles with varying morphologies, and temperature responsive properties utilizing a Pluronic F127/dextran aqueous two-phase system (ATPS) assisted self-assembly. The PLGA polymer, when emulsified in Pluronic F127/dextran ATPS, forms unique microparticle structures due to ATPS guided-self assembly. Depending on the PLGA concentration, the particles either formed a core-shell or a composite microparticle structure. The microparticles facilitate the simultaneous incorporation of both hydrophobic and hydrophilic molecules, due to their amphiphilic macromolecule composition. Further, due to the lower critical solution temperature (LCST) properties of Pluronic F127, the particles exhibit temperature responsiveness. The ATPS based microparticle formation demonstrated in this study, serves as a novel platform for PLGA/polymer based tunable micro/nano particle and polymersome development. The unique properties may be useful in applications such as theranostics, synthesis of complex structure particles, bioreaction/mineralization at the two-phase interface, and bioseparations.

 

Kim, S.J.; Lesher-Perez, S.C.; Kim, B.C.; Yamanashi, C.; Labuz, J.; Leung, B; Takayama, S.; “Pharmacokinetic profile that reduces nephrotoxicity of gentamicin in a perfused kidney-on-a-chip.” Biofabrication. 2016. DOI: 10.1088/1758-5090/8/1/015021.

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Nephrotoxicity is often underestimated because renal clearance in animals is higher compared to in humans. Here we illustrate the potential to fill in such pharmacokinetic gaps between animals and humans using a microfluidic kidney model. As an initial demonstration, we compare nephrotoxicity of a drug, administered at the same total dosage, but using different pharmacokinetic regimens. The data show that gentamicin disrupts cell–cell junctions, increases membrane permeability, and decreases cell viability particularly with prolonged low-level exposure. Importantly a bolus injection mimicking regimen alleviates much of the nephrotoxicity compared to the continuous infused regimen. In addition to potential relevance to clinical gentamicin administration regimens, the results are important in demonstrating the general potential of using microfluidic cell culture models for pharmacokinetics and toxicity studies.

 

Wang, J.; Khafagy, E.S.; Khanafer, K.; Takayama, S.; ElSayed, M.E.H; “Organization of Endothelial Cells, Pericytes, and Astrocytes into a 3D Microfluidic in Vitro Model of the Blood–Brain Barrier.” Mol Pharm. 2016. DOI: 10.1021/acs.molpharmaceut.5b00805.

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The endothelial cells lining the capillaries supplying the brain with oxygen and nutrients form a formidable barrier known as the blood–brain barrier (BBB), which exhibits selective permeability to small drug molecules and virtually impermeable to macromolecular therapeutics. Current in vitro BBB models fail to replicate this restrictive behavior due to poor integration of the endothelial cells with supporting cells (pericytes and astrocytes) following the correct anatomical organization observed in vivo. We report the coculture of mouse brain microvascular endothelial cells (b.End3), pericytes, with/without C8-D1A astrocytes in layered microfluidic channels forming three-dimensional (3D) bi- and triculture models of the BBB. Trans-endothelial electrical resistance (TEER) values and permeability screening of [14C]-mannitol and [14C]-urea indicated that the triculture model is a robust in vitro model of the BBB.

 

Lee, J.; Bathany, C.; Ahn, KY; Takayama, S.; Jung, W.; “Volumetric monitoring of aqueous two phase system droplets using time-lapse optical coherence tomography.” Laser Phys Lett. 2016. DOI: 10.1088/1612-2011/13/2/025606.

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We present a volumetric monitoring method to observe the morphological changes of aqueous two phase system (ATPS) droplets in a microfluidic system. Our method is based on time-lapse optical coherence tomography (OCT) which allows the study of the dynamics of ATPS droplets while visualizing their 3D structures and providing quantitative information on the droplets. In this study, we monitored the process of rehydration and deformation of an ATPS droplet in a microfluidic system and quantified the changes of its volume and velocity under both static and dynamic fluid conditions. Our results indicate that time-lapse OCT is a very promising tool to evaluate the unprecedented features of droplet-based microfluidics.

 

2015

Kim, S.J.; Takayama, S.; “Organ-on-a-chip and the kidney.” Kidney Res Clin Pract. 2015. DOI: 10.1016/j.krcp.2015.08.001.

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Traditional approaches to pathophysiology are advancing but still have many limitations that arise from real biologic systems and their associated physiological phenomena being too complicated. Microfluidics handles small volumes of fluids and may apply to various applications such as DNA analysis chips, other lab-on-a-chip analyses, micropropulsion, and microthermal technologies. Organ-on-a-chip applications allow the fabrication of minimal functional units of a single organ or multiple organs. Relevant to the field of nephrology, renal tubular cells have been integrated with microfluidic devices for making kidneys-on-a-chip. Although still early in development, kidneys-on-a-chip are showing potential to provide a better understanding of the kidney to replace some traditional animal and human studies, particularly as more cell types are incorporated toward the development of a complete glomeruli-on-a-chip.

 

Dixon, A.R.; Bathany, C.; Tsuei, M.; White, J.; Barald, K.F.; Takayama, S.; “Recent developments in multiplexing techniques for immunohistochemistry.” Expert Rev Mol Diagn. 2015. DOI: 10.1586/14737159.2015.1069182.

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Methods to detect immunolabeled molecules at increasingly higher resolutions, even when present at low levels, are revolutionizing immunohistochemistry (IHC). These technologies can be valuable for the management and examination of rare patient tissue specimens, and for improved accuracy of early disease detection. The purpose of this article is to highlight recent multiplexing methods that are candidates for more prevalent use in clinical research and potential translation to the clinic. Multiplex IHC methods, which permit identification of at least 3 and up to 30 discrete antigens, have been divided into whole-section staining and spatially-patterned staining categories. Associated signal enhancement technologies that can enhance performance and throughput of multiplex IHC assays are also discussed. Each multiplex IHC technique, detailed herein, is associated with several advantages as well as tradeoffs that must be taken into consideration for proper evaluation and use of the methods.

 

Cavnar, S.P.; Rickelmann, A.D.; Meguiar, K.F.; Xiao, A.; Dosch, J.; Leung, B.M.; Lescher-Perez, S.C.; Chitta, S.; Luker, K.E.; Takayama, S. ;Luker, G.D.; “Modeling Selective Elimination of Quiescent Cancer Cells from Bone Marrow.” Neoplasia. 2015. DOI: 10.1016/j.neo.2015.08.001.

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Patients with many types of malignancy commonly harbor quiescent disseminated tumor cells in bone marrow. These cells frequently resist chemotherapy and may persist for years before proliferating as recurrent metastases. To test for compounds that eliminate quiescent cancer cells, we established a new 384-well 3D spheroid model in which small numbers of cancer cells reversibly arrest in G1/G0 phase of the cell cycle when cultured with bone marrow stromal cells. Using dual-color bioluminescence imaging to selectively quantify viability of cancer and stromal cells in the same spheroid, we identified single compounds and combination treatments that preferentially eliminated quiescent breast cancer cells but not stromal cells. A treatment combination effective against malignant cells in spheroids also eliminated breast cancer cells from bone marrow in a mouse xenograft model. This research establishes a novel screening platform for therapies that selectively target quiescent tumor cells, facilitating identification of new drugs to prevent recurrent cancer.

 

Shin, H.; Han, C.; Labuz, J.M. ;Kim, J.; Kim, J.; Cho, S.; Gho, Y.S.; Takayama, S.; Park, J.; ” High-yield isolation of extracellular vesicles using aqueous two-phase system.” Sci Rep. 2015. DOI: 10.1038/srep13103.

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Extracellular vesicles (EVs) such as exosomes and microvesicles released from cells are potential biomarkers for blood-based diagnostic applications. To exploit EVs as diagnostic biomarkers, an effective pre-analytical process is necessary. However, recent studies performed with blood-borne EVs have been hindered by the lack of effective purification strategies. In this study, an efficient EV isolation method was developed by using polyethylene glycol/dextran aqueous two phase system (ATPS). This method provides high EV recovery efficiency (~70%) in a short time (~15 min). Consequently, it can significantly increase the diagnostic applicability of EVs.

 

Raghavan, S.; Ward, M.R.; Rowley, K.R.; Wold, R.M.; Takayama, S.; Buckanovich, R.J.; Mehta, G.; ” Formation of stable small cell number three-dimensional ovarian cancer spheroids using hanging drop arrays for preclinical drug sensitivity assays.” Gynecol Oncol. 2015. DOI: 10.1016/j.ygyno.2015.04.014.

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Ovarian cancer spheroids were generated from limited cell numbers in high throughput 384 well hanging-drop plates with high viability. Spheroids demonstrate therapeutic resistance relative to cells in traditional 2D culture. Stable incorporation of low cell numbers is advantageous when translating this research to rare patient-derived cells. This system can be used to understand ovarian cancer spheroid biology, as well as carry out preclinical drug sensitivity assays.

 

Han, C.; Takayama, S.; Park, J.; ” Formation and manipulation of cell spheroids using a density adjusted PEG/DEX aqueous two phase system.” Sci Rep. 2015. DOI: 10.1038/srep11891.

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Various spheroid formation techniques have been widely developed for efficient and reliable 3-D cell culture research. Although those efforts improved many aspects of spheroid generation, the procedures became complex and also required unusual laboratory equipment. Many recent techniques still involve laborious pipetting steps for spheroid manipulation such as collection, distribution and reseeding. In this report, we used a density-controlled polyethylene glycol and dextran aqueous two phase system to generate spheroids that are both consistent in size and precisely size-controllable. Moreover, by adding a few drops of fresh medium to the wells the contain spheroids, they can be simply settled and attached to the culture surface due to reduced densities of the phases. This unique attribute of the technique significantly reduces the numerous pipetting steps of spheroid manipulation to a single pipetting; therefore, the errors from those steps are eliminated and the reliability and efficiency of a research can be maximized.

 

Sumit, M.; Neubig, R.R.; Takayama, S.; Linderman, J.J.; ” Band-pass processing in a GPCR signaling pathway selects for NFAT transcription factor activation.” Integr Biol. 2015. DOI: 10.1039/C5IB00181A.

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Biological processes are influenced by the timing of critical signals. Using a microfluidic delivery system with real-time assessment of cellular calcium and calcium-regulated transcription factor NFAT, we evaluated how the timing of extracellular ligand pulses affects cell signaling events. We found that lesser amounts of ligand stimulation can give more efficient NFAT activation when stimuli are timed appropriately. Mechanistically, the receptor and NFAT transcription factor motifs form a band-pass filter optimized for intermediate frequencies of stimulation. Distinct optima are found for two closely related NFAT isoforms. Computational modeling suggests that the band-pass nature of signaling pathways may be a generic theme. Our findings may facilitate the design of therapeutic interventions and the development of enhanced in vitro cell culture protocols.

 

Hu, Y.; Bian, S.; Grotberg, J.; Filoche, M.; White, J.; Takayama, S.; Grotberg, J.B.; ” A microfluidic model to study fluid dynamics of mucus plug rupture in small lung airway.” Biomicrofluidics. 2015. DOI: 10.1063/1.4928766.

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Fluid dynamics of mucus plug rupture is important to understand mucus clearance in lung airways and potential effects of mucus plug rupture on epithelial cells at lung airway walls. We established a microfluidic model to study mucus plug rupture in a collapsed airway of the 12th generation. Mucus with high yield stress leads to high shear stress, and therefore would be more likely to cause epithelial cell damage. Crackling sounds produced with plug rupture might be more detectable for gels with higher concentration.

 

Yamanashi, C.D.; Chiu, J.H.C.; Takayama, S.; ” Systems for multiplexing homogeneous immunoassays.” Bioanalysis. 2015. DOI: 10.4155/bio.15.78.

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High-throughput multiplex protein biomarker assays continue to gain significance in the fields of biomarker discovery and drug development, due to their economical use of not only the precious clinical biological samples but also expensive reagents. Among these platforms, homogeneous multiplex systems have potential for short assay run times and cost-effective reagent consumptions. However, these systems must overcome challenges of signal cross talk and biochemical cross-reactivity. Despite these obstacles, several homogeneous multiplex immunoassays have been demonstrated. These include fluorescent polarization, fluorescent resonance energy transfer with quantum dots or graphene, luminescent oxygen-channeling immunoassay coupled with aqueous two-phase systems and DNA proximity assays. The balance between speed/simplicity and high multiplexing and robustness of these homogeneous multiplex immunoassays are discussed in this review.

 

Chung, K.; Kwon, M.S.; Leung, B.M.; Wong-Foy, A.G.; Kim, M.S.; Takayama, S.; Gierschner, J.; Matzger, A.J.; Kim, J.; ” Shear-Triggered Crystallization and Light Emission of a Thermally Stable Organic Supercooled Liquid.” ACS Cent Sci. 2015. DOI: 10.1021/acscentsci.5b00091.

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Even though molecules can form supercooled liquids by rapid cooling, crystalline organic materials readily undergo a phase transformation to an energetically favorable crystalline phase upon subsequent heat treatment. Opposite to this general observation, here, we report molecular design of thermally stable supercooled liquid of diketopyrrolopyrrole (DPP) derivatives and their intriguing shear-triggered crystallization with dramatic optical property changes. By systematic investigation on supercooled liquid formation of crystalline DPP derivatives and their correlation with chemical structures, we reveal that the origin of this thermally stable supercooled liquid is a subtle force balance between aromatic interactions among the core units and van der Waals interactions among the aliphatic side chains acting in opposite directions. Moreover, by applying shear force to a supercooled liquid DPP8 film at different temperatures, we demonstrated direct writing of fluorescent patterns and propagating fluorescence amplification, respectively.

 

Zhang, Y.S.; Ribas, J.; Nadhman, A.; Aleman, J.; Selimovic, S.; Lesher-Perez, S.C.; Wang, T.; Manoharan, V.; Shin, S.R.; Damilano, A; Annabi, N.; Docmeci, M.R.; Takayama, S.; Khademhosseini, A.; “A cost-effective fluorescence mini-microscope for biomedical applications.” Lab Chip. 2015. DOI: 10.1039/C5LC00666J.

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This work built on a previous bright-field mini-microscope prototype, developing a fluorescent on-chip mini-microscope from off-the-shelf components and a webcam, for biomedical applications. This mini-microscope was capable of detecting biochemical parameters such as cell viability, and microenvironment levels of oxygen, through the use of an oxygen sensitive fluorescent dye. In addition, the mini-microscope could, in real-time, monitor cellular migration in microfluidic liver bioreactors and analyze the beating of cardiac bioreactors. The mini-microscope system is cheap, and due to its modular composition allows convenient integration with a wide variety of pre-existing platforms such as cell culture plates, microfluidic devices, and organs-on-a-chip systems.

 

Moraes, C.; Labuz, J.M.; Shao, Y.; Fu, J.; Takayama, S.; ” Supersoft lithography: candy-based fabrication of soft silicone microstructures.” Lab Chip. 2015. DOI: 10.1039/C5LC00722D.

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We designed a fabrication technique able to replicate microstructures in soft silicone materials (E < 1 kPa). Sugar-based ‘hard candy’ recipes from the confectionery industry were modified to be compatible with silicone processing conditions, and used as templates for replica molding. Microstructures fabricated in soft silicones can then be easily released by dissolving the template in water. We anticipate that this technique will be of particular importance in replicating physiologically soft, microstructured environments for cell culture, and demonstrate a first application in which intrinsically soft microstructures are used to measure forces generated by fibroblast-laden contractile tissues.

 

Leung, B.M.; Lesher-Perez, S.C.; Matsuoka, T.; Moraes, C.; Takayama, S.; ” Media additives to promote spheroid circularity and compactness in hanging drop platform.” Biomater Sci. 2015. DOI: 10.1039/C4BM00319E.

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Three-dimensional spheroid cultures have become increasingly popular as drug screening platforms, especially with the advent of different high throughput spheroid forming technologies. However, comparing drug efficacy across different cell types in spheroid culture can be difficult due to variations in spheroid morphologies and transport characteristics. Improving the reproducibility of compact, circular spheroids contributes to standardizing and increasing the fidelity of the desired gradient profiles in these drug screening three-dimensional tissue cultures. In this study we discuss the role that circularity and compaction has on spheroids, and demonstrate the impact methylcellulose (MethoCel) and collagen additives in the culture media can contribute to more compact and circular spheroid morphology. We demonstrate that improved spheroid formation is not a simple function of increased viscosity of the different macromolecule additives, suggesting that other macromolecular characteristics contribute to improved spheroid formation.

 

Frampton, J.P.; Lai, D.; Lounds, M.; Chung, K.; Kim, J.; Mansfield, J.F.; Takayama, S.; ” Elongation of Fibers from Highly Viscous Dextran Solutions Enables Fabrication of Rapidly Dissolving Drug Carrying Fabrics.” Adv Healthc Mater. 2015. DOI: 10.1002/adhm.201400287.

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A simple method is presented for forming thread-like fibers from highly viscous dextran solutions. Based on the cohesive and adhesive forces between a dextran solution and the substrate to which it is applied, multiple fibers of approximately 10 μm in diameter can be elongated simultaneously. These fibers can be woven into multiple layers to produce fabrics of varying fiber orientations and mechanical properties. Various bioactive agents can be incorporated into the dextran solution prior to fiber formation, including hemostatic and antibiotic agents. Fabrics containing thrombin are capable of coagulating human platelet poor plasma in vitro. Fabrics containing antibiotics are capable of suppressing bacterial growth in a disk diffusion assay. These data suggest that this new material composed entirely of dextran has promise as a drug delivery component in wound dressings.

 

Kim, S-J.; Yokokawa, R.; Lesher-Perez, S.C.; Takayama, S.; “Multiple independent autonomous hydraulic oscillators driven by a common gravity head.” Nat Commun. 2015. DOI: 10.1038/ncomms8301.

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In this work, we build on the electronic-fluidic analogy, by generating a microhydraulic circuit which can simultaneously perform multiple independent parallel operations, in an autonomous fashion. This system, enables a user-friendly device with versatile multi-functional outputs, that requires minimal control equipment, and can simply be powered by a convenient gravity head as the pumping force. The microhydraulic circuits presented in this work could perform parallel oscillations over a wide range of periods (0.4 s – 2 h), as well as achieve differential flow rates, ranging from 0.02 dyn cm−2 to 58 dyn cm−2. The broad range of oscillation periods and shear stresses achieved, span the majority of physiological ranges such that these microhydraulic circuits, could be used to study various biological rhythms. Due to their versatility, these devices have implications beyond cell culture applications to become critical modules for a broad range of sophisticated microfluidic operations.

 

Chang, S.L.; Cavnar, S.P.; Takayama, S.; Luker, G.D.; Linderman, J.J. “Cell, Isoform, and Environment Factors Shape Gradients and Modulate Chemotaxis.” PLOS One. 2015. DOI: 10.1371/journal.pone.0123450.

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One shortcoming of our previously developed source-sink migration model is our inability to visualize molecular-scale events that contribute to gradient formation, sensing, and chemotaxis. In a three-part collaboration between the Linderman, Luker, and Takayama labs, we develop an agent-based computational model to predict key parameters in chemotaxis and address our previous experimental shortcomings. Using this model we found that the high affinity of CXCL12-isoforms to extracellular surfaces aids gradient formation and limits our ability to fully inhibit these processes.

 

Bathany, C.; Han, J-R.; AbiSamra, K.; Takayama, S.; Cho, Y-K. “An electrochemical-sensor system for real-time flow measurements in porous materials.” Biosens. Bioelec. 2015. DOI: 10.1016/j.bios.2015.03.002.

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We develop and characterize an electrical flow sensor for use in paper-based microfluidic bioassays. By measuring the amperometric changes due to fluid wicking through paper we are able to monitor flow without disrupting it. We assess this technique for different nitrocellulose papers with a variety of surface treatments and coatings.

 

 

 

Lai, D.; Takayama, S.; Smith, G.D. “Recent microfluidic devices for studying gamete and embryo biomechanics.” J. Biomech. 2015. DOI: 10.1016/j.jbiomech.2015.02.039.

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The technical challenges of single cell biomechanics research include high monetary cost, lab, and time. Traditional measuring techniques typically used for large samples also operate on assumptions that begin to waver in the microscope. These challenges area a good match tot he strengths of microfluidic devices. New scientific discoveries using micro fluids in the fertilization and embryo development process, of which biomechanics is a major subset of interest, is crucial to fuel the continual improvement of the clinical practice in assisted reproduction. This review highlights some recent microfluidic device design and function, and the application of fundamental biomechanics principles are used to improve outcomes of cryopreservation.

 

Frampton, J.P.; Leung, B.M.; Bingham, E.L.; Lesher-Perez, S.C.; Wang, J.D.; Sarhan, H.T.; El-Sayed, M.E.H.; Feinberg, S.E.; Takayama, S. “Rapid self-assembly of macroscale tissue constructs at biphasic aqueous interfaces.” Adv Fun Mater. 2015. DOI: 10.1002/adfm.201403825.

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Macroscopic tissue constructs composed entirely of cells are formed using the interfacial properties of aqueous two-phase systems. The constructs form rapidly in as little as two hours using a variety of cell types, offering a new methodology for fabricating tissue-engineered in vitro models and cell-based materials for regenerative therapies. This technology was applied for producing skin constructs from suspensions of primary human keratinocytes, which attached and integrated with a decellularized dermal equivalent.

 

Lee, G-H.; Kim, S-H.; Kang, A.; Takayama, S.; Lee, S-H.; Park, J.Y. “Deformable L-shaped microwell array for trapping pairs of heterogeneous cells.” J Micromech Microeng. 2015. DOI: 10.1088/0960-1317/25/3/035005.

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Heterogeneous cell pairs can be reliably patterned in L-shaped PDMS microwells by sequentially stretching and loading an arrayed device in orthogonal directions. These cell pairs can then be used to further study both direct and paracrine mechanisms of intracellular communication with the bulk solution above the microcells diluting soluble factors outside of the microwell and preventing unwanted communication between cell pairs.

 

Lai, D.; Chiu, J.H-C.; Smith, G.D.; Takayama, S. “Microfluidic for assisted reproductive technologies.” Book chapter in: Microdfluidics for Medical Applications. 2015.

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Infertility affects 10% of couples in the United States. As fertility is a major life-issue, there is a large motivation for the advancement of assisted reproductive technologies for the purposes of cost-efficiency, and enhanced outcomes. Microfluidics provides one possible strategy to tackle this challenge as its key strengths involve low materials used, high speed, and high efficiency. We highlight some microfluidic devices for sperm sorting, oocyte quality assessments, in vitro fertilizations, embryo and oocyte cryopreservation, embryo culture, and embryo analysis.

 

Kim, B.C.; Weerappuli, P.; Thouless, M.D.; Takayama, S. “Fracture fabrication of a multi-scale channel device that efficiently captures and linearizes DNA from dilute solutions.” Lab Chip. 2015. DOI: 10.1039/C4LC01294A.

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This paper describes a simple technique for patterning channels on elastomeric substrates, at two distinct scales of depth, through the use of controlled fracture. This system is utilized for the successful capture and linearization of DNA from a dilute solution by a two-step ‘concentrate-then-linearize’ procedure.

 

2014

Lai, D.; Ding, J.; Smith, G.W.; Smith, G.D.; Takayama, S. “Slow and steady cell shrinkage reduces osmotic stress in bovine and murine oocyte and zygote vitrification.” Human Reproduction. 2014. DOI: 10.1093/humrep/deu284.

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The use of a new CPA exchange protocol made possible by automated microfluidics improved oocyte and zygote vitrification with superior morphology as indicated by a smoother cell surface, higher sphericity, higher cytoplasmic lipid retention, less cytoplasmic leakage and higher developmental competence compared with conventional methods. The theory and approach of eliminating osmotic stress by decreasing shrinkage rate is complementary to the prevalent osmotic stress theory in cryobiology which focuses on a minimum cell volume at which the cells shrink. The auto-microfluidic protocol described here has immediate applications for improving animal and human oocyte, zygote and embryo cryopreservation. On a fundamental level, the clear demonstration that at the same minimum cell volume, cell shrinkage rate affects sublethal damage should be broadly useful for cryobiology.

 

Leung; B.M.*; Moraes, C.*; Cavnar, S.P.; Luker, K.E.; Luker, G.D; Takayama, S. “Microscale 3D collagen cell culture assays in conventional flat-bottom 384-well plates.” Journal of Laboratory Automation. 2014. DOI: 10.1177/2211068214563793.

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We know that 3D cultures can be more realistic than growing cells on hard, flat 2D surfaces. However, conducting high-throughput screens in 3D is extremely challenging from a technical, logistical and cost perspective. To address these issues, Brendan and Chris developed a micro-scale 3D culture assay that can be integrated directly into existing high-throughput screening infrastructure, is only slightly more expensive than conventional 2D assays, and eliminates the transport limitations typically associated with 3D systems. A preliminary screen of breast cancer cell chemo-responsiveness showed dramatic differences in chemotherapeutic activity between 2D and 3D cultures.

 

Lesher-Perez, S.C.; Weerappuli; Kim, S-J.; Zhang, C.; Takayama, S. “Predictable duty cycle modulation through coupled pairing of syringes with microfluidic oscillators.” Micromachines. 2014. DOI: 10.3390/mi5041254.

LINK

This paper describes a novel approach to achieve distinct, controllable, reproducible duty cycles in a self-regulating microfluidic oscillator using the coordinated modulation of input volumetric flow rate ratio and fluidic capacitance ratio. Our demonstration uses a straightforward, simple experimental system where fluid inflow is provided by two syringes (of symmetric or asymmetric cross-sectional area) mounted upon a single syringe pump; along with the setup, we present a simplified expression to determine the microfluidic oscillators duty cycle as a function of syringe cross-sectional area. Applying this simplified expression, we robustly predicted, and achieved desired duty cycles ranging from 50% to 90% under different asymmetric inflow conditions.

 

Kojima, T.; Moraes, C.; Cavnar, S.P.; Luker, G.D.; Takayama, S. “Surface-templated hydrogel patterns prompt matrix-dependent migration of breast cancer cells towards chemokine-secreting cells.” Acta Biomaterialia. 2014. DOI: 10.1016/j.actbio.2014.11.033.

LINK

This paper describes a novel technique to fabricate spatially-defined cell-laden collagen, hydrogels, using patterned, non-adhesive polyacrylamide-coated polydimethylsiloxane (PDMS), surfaces as a template. Precisely patterned embedded co-cultures of breast cancer cells and, chemokine-producing cells generated with this technique, revealed matrix- and chemokine isoformdependent, migration of cancer cells. CXCL12 chemokine-secreting cells induce significantly more, chemotaxis of cancer cells when the 3D extracellular matrix includes components that bind the, secreted CXCL12 chemokines. The methods described here should be broadly applicable for study of physiological migration, of many different cell types in response to a variety of chemoattractants.

 

Leung, B.M.; Lesher-Perez, S.C.; Matsuoka, T.; Moraes, C.; Takayama, S. “Media additives to promote spheroid circularity and compactness in hanging drop platform.” Bomaterials Science. 2014. DOI: 10.1039/C4BM00319E.

LINK

Spheroid cultures have become increasingly popular as drug screening platforms, however, comparing drug efficacy across different cell types can be difficult due to variations in spheroid morphologies and transport characteristics. In this study we demonstrate the impact of methylcellulose (MethoCel) and collagen additives in culture media on the compactness and circularity of spheroid morphology. We show that improved spheroid formation is not a simple function of increased viscosity of the different macromolecule additives. Of the various macromolecular additives tested for hanging drop culture, MethoCel provided the most desirable spheroid formation, also its high viscosity improved the ease of imaging of cellular spheroids within hanging drop cultures by reducing motion-induced image blur.

 

Takayama, S.; White, J.B.; Zhang, C. “Lungs-on-a-Chip.” Book chapter in Inhalation Toxicology 2014. Editors H Salem and SA Katz.

LINK

This chapter provides a brief overview of the state of the art in mirofluidic cell culture models commonly referred to as lungs-on-a-chip. The difference between conventional dish culture and these microfluidic models of the lung include incorporation of lung dynamics and mechanical stimulation.

 

 

 

 

 

Frampton, J.P.; Tsuei, M.; White, J.B.; Abraham, A.T.; Takayama, S. “Aqueous two-phase system-mediated antibody micro patterning enables multiplexed immunostaining of cell monolayers and tissues.” Biotech J. 2014. DOI: 10.1002/biot.201400271.

LINK

This fully aqueous immunostaining method enables detection of multiple proteins in different regions of a single fixed cell culture, explant or tissue section sample through localization of small volumes of antibody solutions that would otherwise evaporate or become too diluted in the bulk solution to produce reliable staining.

 

Kim, B.C.*; Moraes, C.*; Huang, J.; Matsuoka, T.; Thouless, M.D.; Takayama, S. “Fracture-based fabrication of normally-closed, adjustable and fully reversible micro-scale fluidic channels.” Small. 2014. DOI: 10.1002/smll.201400147.

LINK

Multilayered materials are engineered such that applied tension generates micro-scale cracks at pre-defined positions and with specified dimensions. These cracks can be used as normally-closed and fully reversible microfluidic channels, and should be applicable in a variety of contexts. Here, we demonstrate manipulation of chromatin released from single cells for subsequent epigenetic analysis.

 

Simon, A.B.; Frampton, J.P.; Huang, N-T.; Kurabayashi, K.; Paczesny, S.; Takayama, S. “Aqueous two-phase systems enable multiplexing of homogeneous immunoassays.” Technology. 2014. DOI: 10.1142/S2339547814500150.

LINK

In this manuscript, we enable, for the first time, multiplexing of amplified luminescent proximity homogeneous assays (AlphaLISAs) by co-localizing antibody-bead reagents in droplets of immiscible aqueous polymers. Not only is our no-wash immunoassay completed in two hours, but it also highly specific and highly sensitive because it prevents the antibody cross-reaction problem that plagues many current multiplex assays. These characteristics indicate that our assay is a valuable alternative detection method to singleplex AlphaLISA and enzyme-linked immunosorbent assay (ELISA) for protein quantification in cell culture supernatant and human plasma.

 

Frampton, J.P.; White, J.B.; Simon, A.B.; Tsuei, M.; Paczesny, S.; Takayama, S. “Aqueous two-phase system patterning of detection antibody solutions for cross-reaction free multiplex ELISA.” Sci. Rep. 2014. DOI: 10.1038/srep04878.

LINK

Accurate disease diagnosis, patient stratification and biomarker validation require the analysis of multiple biomarkers. This is often accomplished using multiplex immunoassays. Unfortunately, conventional multiplex immunoassays can be prone to cross-reactions among antibody reagents. This paper describes a new approach to suppress cross-reactivity in enzyme-linked immunosorbent assays (ELISAs) using aqueous two-phase systems (ATPSs).

 

Lai, D.; Frampton, J.P.; Tsuei, M.; Kao, A.; Takayama, S. “Label-free direct visual analysis of hydrolytic enzyme activity using aqueous two-phase system droplet phase transitions.” Anal. Chem. 2014. DOI: 10.1021/ac500657k.

LINK

In this paper, we use dextran hydrolysis mediated conversion of polyethylene glycol-dextran aqueous two-phase system droplets to a single phase to visualize enzymatic activity. The combination of a microfluidic droplet system and phase transition observation provides a new, label-free direct measurement method that uses a thermodynamic phenomenon (i.e. phase transition) to analyze a kinetic phenomenon (i.e. enzyme hydrolysis).

 

Cavnar, S.P.; Ray, P.; Moudgil, P.; Chang, S.L.; Luker, K.; Linderman, J.J.; Takayama, S.; Luker, G. “Microfluidic source-sink model reveals effects of biophysically distinct CXCL12-isoforms in breast cancer chemotaxis.” Integr. Biol. 2014. DOI: 10.1039/C4IB00015C.

LINK

Chemotactic gradients and cell migration depend upon on an intricate balance among chemokine secretion, degradation, and signaling. Using a microfluidic device to facilitate source-sink gradient formation, we reveal how collective levels and interactions of CXCL12 isoforms and receptors CXCR4 and CXCR7 control chemotaxis, a critical process in metastasis.

 

Labuz, J.M.; Takayama, S. “Elevating Sampling.” Lab Chip. 2014. DOI: 10.1039/C4LC00125G.

LINK

A critical step in for any microfluidic system is sampling – collection, preparation, and introduction of a volume of interest into a device. This perspective examines important micro- and nano-fluidic concepts in this field and identifies current opportunities and challenges in this space.

 

Moraes, C.; Kim, B.C.; Zhu, X.; Mill, K.L.; Dixon, A.R.; Thouless, M.D.; Takayama, S. “Defined topologically-complex protein matrices to manipulate cell shape via three-dimensional fiber-like patterns.” Lab Chip. 2014. DOI: 10.1039/C4LC00122B.

LINK

Three-dimensional culture systems present fibrous adhesive matrix architectures to encapsulated cells, which likely regulate aspects of cell function. In this work, we utilize crack formation in multilayered materials to generate well-defined, topologically-complex, ‘fiber-like’ adhesive micropatterns, enabling the culture of individual cells in precisely-controlled, three-dimensional adhesive microstructures.

 

Dixon, A.R.; Rajan, S.; Kuo, C-H.; Bersano, T.; Wold, R.; Futai, N.; Takayama, S.; Mehta, G.; “Microfluidic device capable of medium recirculation for non-adherent cell culture.” Biomicrofluidics 2014. DOI: 10.1063/1.4865855.

LINK

Microfluidic braille platforms enable a variety of valving and pumping in an integrated, on-chip fashion. Here, we describe a computationally-informed braille microfluidic device capable of supporting non-adherent cell culture studies. We then use this “recirc-refresh” device to culture HL-60 cells and monitor DMSO-induced differentiation over 4 days.

 

Kim, B.C.; Moraes, C.; Huang, J.; Thouless, M.D.; Takayama, S. “Fracture-based. micro- and nanofabrication for biological applications.” Biomaterials Science 2014. DOI: 10.1039/c3bm60276a.

LINK

While fracture is generally considered to be undesirable in various manufacturing processes, delicate control of fracture can be successfully implemented to generate structures at micro/nano length scales.

 

 

 

Hu, Y.; Bian, S.; Filoche, M.; Grotberg, J.C.; White, J.; Takayama, S.; Grotberg, J.B. “Flow and Sound Generation in Human Lungs: Models of Wheezes and Crackles.” Fluid-Structure-Sound Interactions and Control 2014. DOI: 10.1007/978-3-642-40371-2_44.

LINK

This article models the reopening of collapsed airways in the lung in which collapse is facilitated by the formation of a mucus-like liquid plug across the entire cross-section of the airway. Non-Newtonian mucus-like gels were formulated by enriching deionized water with Carbopol 940 polymer, and the gel-like plugs were propagated down a microfluidic channel using an air-filled syringe pump. Fluid properties and propagation characteristics, including viscoelasticity, yield stress, critical pressure drop, and plug motion and rupture were analyzed and discussed in the context of lung pathophysiology and airway reopening.

 

Mosadegh, B.; Mazzeo, A.D.; Shedperd, R.F.; Morin, S.A.; Gupta, U.; Sani, I.Z.; Lai, D.; Takayama, S.; Whitesides, G. “Control of soft machines using actuators operated by a Braille display.” Lab Chip 2014. DOI: 10.1039/C3LC51083B.

LINK

Reconfigurable complex pneumatic manifolds by computer-controlled Braille display and micropneumatic device. The positioning and geometries of the valves and channels dictate its function. The function of the pneumatic manifold can be reconfigured by simply exchanging the micropnuematic device with a different design.

 

2013

Hiramatsu, R.; Matsuoka, T.; Kimura-Yoshida, C.; Han, S-W.; Mochida, K.; Adachi, T.; Takayama, S.; Matsuo, I. “External Mechanical Cues Trigger the Establishment of the Anterior-Posterior Axis in Early Mouse Embryos.” Dev. Cell 2013. DOI: 10.1016/j.devcel.2013.09.026.

LINK

Mouse anterior-posterior axis polarization is preceded by formation of the distal visceral endoderm (DVE). We show that external mechanical cues exerted by the interaction between embryo and maternal uterine tissues establish the anterior-posterior axis by breaching the basement membrane and allowing epiblast cells to transmigrate into DVE cells.

 

Kim, B.C.; Matsuoka, T.; Moraes, C.; Huang, J.; Thouless, M.D.; Takayama, S. “Guided fracture of films on soft substrates to create micro/nano-feature arrays with controlled periodicity.” Sci. Reports 2013. DOI: 10.1038/srep03027.

LINK

We report a propagation-controlled technique to guide fracture of thin films supported on soft substrates to create crack arrays with highly controlled periodicity. Precision crack patterns are obtained by the use of strategically positioned stress-focusing V-notch features under conditions of slow application of strain to a degree where the notch features and intrinsic crack spacing match. This simple but robust approach provides a variety of precisely spaced crack arrays on both flat and curved surfaces.

 

Huang, J.; Kim, B.C.; Takayama, S.; Thouless, M.D. “The control of crack arrays in thin films.” J. Mat Sci. 2013. DOI: 10.1007/s10853-013-7700-3.

LINK

The control of crack arrays depends on the nature of the intrinsic flaw population. If there is a relatively large density of long flaws, as commonly assumed in fracture mechanics analyses, reliable crack patterns can be obtained fairly robustly using relatively blunt geometrical features to initiate cracks, provided the applied strain is carefully matched to the properties of the system and the desired crack spacing. This process is analyzed both for cracks confined to the thickness of a film and for cracks growing into a substrate.

 

 

Cavnar, S.P.; Salomonsson, E.; Luker, K.E.; Luker, G.D.; Takayama, S. “Transfer, Imaging, and Analysis Plate for Facile Handling of 384 Hanging Drop 3D Tissue Spheroids.” JALA. 2013. DOI: 10.1177/2211068213504296.

LINK

High throughput formation and analysis of uniform 3D microtissues is a challenge for many applications. Here we leverage our previous advances in high throughput hanging drop spheroid formation to develop a complimentary collection and imaging system. This system extends the usability of hanging drop spheroids to allow for stable imaging, bulk spheroid collection, and other downstream analyses.

 

Bathany, C.; Park, J.; Cho, Y.K.; Takayama, S. “Dehydrated Aqueous Two-Phase System Micro-domain Retain Shape upon Rehydration to Allow Patterned Reagent Delivery to Cells.” J Mat Chem B. 2013. DOI: 10.1039/C3TB21004A.

LINK

When coupled with polymers that form aqueous two-phase systems, dried reagent patches can be used to form stable micro-domians. In this instance, we use dextran and polyethylene glycol as phase-forming polymers to facilitate the delivery of trypsin to dissociate cells from a region of a previously intact monolayer. This technique is useful for wound healing assays and such a delivery format may enable ready made, stable “tablets” or “patches” that can be sold commercially and used for on demand biopatterning.

 

Matsuoka, T.M; Kim, B.C.; Moraes, C.; Han, M.; Takayama, S. “Micro- and nanofluidic technologies for epigenetic profiling.” Biomicrofluidics. 2013. DOI: 10.1063/1.4816835.

LINK

This review paper provides an overview of the impact recent micro- and nanotechnologies have made in studying epigenetic structures. The biological importance and challenges associated with epigenetics prompts the need for mapping histone modifications on chromatin, rather than rely on DNA sequencing technologies. We summarize existing technologies for performing these analyses, and emphasize the unique advantages of micro- and nanofluidic technologies in contributing to this field.

 

Moraes, C.; Simon, A.B.; Putnam, A.J.; Takayama, S. “Aqueous two-phase printing of cell-containing contractile collagen micro gels.” Biomaterials. 2013. DOI: biomaterials.2013.08.046.

LINK

We demonstrate the use of aqueous two-phase systems to produce miniaturized cell-laden hydrogel constructs. Aqueous two-phase processing eliminates evaporation during the polymerization process, a critical concern with maintaining cell viability in processing such microgels. Collagen contraction is a commonly used assay in a variety of fields, and we develop and validate this approach in miniaturizing the collagen contraction assay. The technique reduces use of expensive reagents, enables the study of rare cell populations, and is easily applied in standard wet-labs: a simple manual micropipette may be used to robustly generate microgels. Furthermore, miniaturizing the assay allows rapid diffusion of large molecules into the gel, enabling the study of timed stimulation profiles in the collagen contraction assay.

 

Dixon, A.R.; Moraes, C.; Csete, M.E; Thouless, M.D.; Philbert, M.A.; Takayama, S. “One-dimensional patterning of cells in silicone wells via compression-induced fracture.” Journal of Biomedical Materials Research Part A. 2013. DOI: 10.1002/jbm.a.34814.

LINK

Previously we have used compression-induced fracture technology to generate cracks on solid PDMS cubes and spheres. The cracks generated with this method share likeness with 1D lines used to recapitulate phenotypical traits of 3D cell culture. In pursuit of developing simple technologies for 3D cell culture, we�ve used the compression-induced fracture method to generate submicron cracks on a shallow well, which can house cells for culturing. The effectiveness of adapting this method lies in inclusion of the shallow well, centered in a PDMS cuboid construct, which improves homogeneity of distributed stresses, and thus, overall uniformity of cracks. This simple system presents itself as a valuable tool for studying the relationship between 1D and 3D cell culture environment.

 

Lai, D.; Labuz, J.M.; Kim, J.; Luker, G.; Shikanov, A.; Takayama, S. “Simple Multi-level Microchannel Fabrication by Pseudo-Grayscale Backside Diffused Light Lithography.” RSC Advances. 2013. DOI: 10.1039/C3RA43834A.

LINK

Conventional fabrication of multi-level devices via photolithography requires either expensive grayscale masking systems or laborious serial exposures. Using diffused light and low-resolution photomasks, we develop a technique for fabricating and arbitrary number of channel heights in a single exposure. Since the photoresist is polymerized from the substrate up, no spincoater is required to obtain high-quality microfluidic channels. We use devices produced using this method for size-based separation of cancer and blood cells as well as follicle and cancer cells.

 

Byun, C.K.; Abi-Samra, K.; Cho, Y-K; Takayama, S. “Pumps for Microfluidic Cell Culture.” Electrophoresis. 2013. DOI: 10.1002/elps.201300205.

LINK

Microfluidics have enable new assays in a variety of life science applications. The past decade has seen the development of a variety of pumping mechanisms to deliver and control fluid flow in such devices. This review summarizes recent advances and analyzes advantages and disadvantages of available microfluidic pump schemes.

 

 

Moraes, C.*; Labuz, J.M.*; Leung, B.M.*; Inoue, M.; Chun, T-H; Takayama, S. “On being the right size: scaling effects in designing a human-on-a-chip.” Integr. Biol. 2013. DOI: 10.1039/C3IB40040A.

LINK

A microfluidic model of the human body or “human on a chip” would have tremendous impact on many fields within the life sciences including drug screening, disease modeling, and biodefense. Already, engineering efforts are underway to recreate organ function and structure in vitro and, in some cases, integrate discrete organ compartments into a self-contained system. Valid, translatable results depend on appropriate scaling of these various compartments – a fact we demonstrate in a series of adipocyte glucose uptake experiments. Since current approaches fail to adequately address issues surrounding the scaling of a generalizable human on a chip, we propose a scaling approach that accounts for the in vivo function of the organ and suggest several engineering techniques that can be used to circumvent problems that may arise as the result of such an approach.

 

Jovic, A.; Wade, S.M.; Neubig, R.R.; Linderman, J.J.; Takayama, S. “Microfluidic interrogation and methematical modeling of multi-regime calcium signaling dynamics.” Integr. Biol. 2013. DOI: 10.1039/C3IB40032H.

LINK

We use pulsed, rather than continuous stimulation of the M3 muscarinic receptor to study calcium signaling within G-protein coupled receptor pathways. Continuous versus periodic and low versus high amplitude ligand signaling were found to elicit different intracellular Ca responses. This variety of responses allowed us to develop a comprehensive mathematical model for multi-regime Ca signaling.

 

Kim, S-J; Paczesny, S.; Takayama, S.; Kurabayashi, K. “Preprogrammed, parallel on-chip immunoassay using system-level capillarity control.” Analytical Chemistry. 2013. DOI: 10.1021/ac401292d.

LINK

To save time over manual execution of ELISA-based immunoassays, we developed an inexpensive capillarity-driven system. Capillarity spontaneously transports multiple sample, reagent, and wash solutions in a passive and preprogrammed manner. This technique reduces the number of pipetting steps by a factor of 5 and we demonstrate detection limits of 8 and 90 pM for CRP and ST2, respectively.

 

Dwidar, M.; Leung, B.M.; Yaguchi, T.; Takayama, S.; Mitchell, R.J. “Patterning Bacterial Communities on Epithelial Cells.” PLOS One. 2013. DOI: 10.1371/journal.pone.0067165.

LINK

This paper describes the method of confining and maintaining two or more distinct colonies of bacteria biofilm over human mammary epithelial cell using ATPS. Pathogenic bioflim causes cell death in underlying epithelium, but this can be mitigated by the addition of bacteria predating Bdellovibrio bacteriovorus, or Balo. This is the first in vitro model that demonstrates the protective effect of Balo on mammalian cells against pathogenic bacteria.

 

Kojima, T.; Takayama, S. “Microscale Determination of Aqueous Two Phase System Binodals by Droplet Dehydration in Oil.” Analytical Chemistry. 2013. DOI: 10.1021/ac400628b.

LINK

This paper analyzes the use of a dehydrating oil system to determine binodal curves of aqueous two phase system (ATPS). Aqueous droplets containing phase-forming polymers are dehydrated at the interface between two immiscible oils. Comparison of the droplet diameter at this phase separation point and at the beginning allows facile calculation of the concentration of polymers that determine the binodal curve. The miniaturized droplet dehydration-based binodals obtained in this manner matched the binodals determined by the conventional diluting method but using several orders of magnitude less sample amounts.

 

Kojima, T.; Takayama, S. “Patchy surfaces stabilize DEX-PEG aqueous two phase system liquid patterns.” Langmuir. 2013. DOI: 10.1021/la400580q.

LINK

This paper analyzes surface chemistry effects to stably pattern aqueous two phase system (ATPS) droplets on chemically modified poly(dimethylsiloxane) (PDMS). PDMS surface modifications studied include primary amine groups, carboxylic acid groups, and neutral polymer surfaces. While homogeneous surfaces of different functional groups affect DEX droplet pinning somewhat, the most stable patterns were realized using surfaces with chemical heterogeneity. Arbitrary DEX solution patterning was achieved on a chemically patchy surface.

 

Frampton, J. P.; Shi, H.; Kao, A.; Parent, J.M.; Takayama, S. “Delivery of Proteases in Aqueous Two-Phase Systems Enables Direct Purification of Stem Cell Colonies from Feeder Cell Co-Cultures for Differentiation into Functional Cardiomyocytes.” Advanced Healthcare Materials. 2013. DOI: 10.1002/adhm.201300049.

LINK

Feeder cell co-culture is used by most stem cell biologist because it maintains stem cell viability and phenotype, is relatively cost effective, and produces consistent results across ESC and IPSC lines. However, for many applications, stem cells need to be purified from the surrounding feeder cells. We developed a method that uses ATPSs for high resolution delivery of enzymes directly to stem cell colonies to remove them from feeder cultures. This technique uses the smallest user-controlled ATPS droplets yet reported and will be useful for high-resolution protein patterning on a variety of other cell types.

 

Frampton, J. P.; White, J. B.; Abraham, A. T.; Takayama, S. “Cell Co-culture Patterning Using Aqueous Two-phase Systems.” J. Vis. Exp. 2013. DOI: 10.3791/50304.

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In this video tutorial we describe how to use ATPSs for patterning cells. We demonstrate patterning of islands, exclusion zones, and co-cultures so that users can adapt this technology to study cell migration and cell-cell interactions of their cells of interest. This technique can be performed using only pipettes, without the need for any specialized equipment.

 

Lee, D; Bolton, O.; Kim, B-C.; Youk, J. H.; Takayama, S.; Kim, J. “Room Temperature Phosphorescence of Metal-free Organic Materials in Amorphous Polymer Matrices.” JACS. 2013. DOI: 10.1021/ja401769g.

LINK

Bright room temperature phosphorescence by embedding a purely organic phosphor into an amorphous glassy polymer matrix. It implies that the reduced beta (beta)-relaxation of isotactic PMMA most efficiently suppresses vibrational triplet decay and allows the embedded organic phosphors to achieve a bright 7.5% phosphorescence quantum yield. It was applied to a microfluidic device integrated with a novel temperature sensor based on the metal-free purely organic phosphors in the temperature-sensitive polymer matrix.

 

Kim, S-J.; Paczesny, S.; Takayama, S.; Kurabayashi, K. “Preprogrammed capillarity to passively control system-level sequential and parallel microfluidic flows.” Lab Chip. 2013. DOI: 10.1039/C3LC50187F.

LINK

The small length scales of microfluidic systems enable capillary flow but few efforts have been made to harness this passive flow for controlled an tunable operations. This paper demonstrates a microfluidic chip capable of controlling flow and sequence passively, without the need for valves or pumps.

 

Kang, E.; Ryoo, J.; Jeong, G.S.; Choi, Y.Y; Jeong, S.M.; Ju, J.; Chung, S.; Takayama, S.; Lee, S-H. “Large-Scale, Ultrapliable, and Free-Standing Nanomembranes.” Advanced Materials. 2013. DOI: 10.1002/adma.201204619.

LINK

We outline and characterize a strategy for generating PDMS membranes as thin as 50 nm. The ultra-thin membranes allow for a simplified treatment of cell monolayer mechanics and we apply them to study stretch-induced injury in epithelia.

 

 

 

Baac, Hyoung Won; Frampton, J.P.; Ok, Jong G.; Takayama, S.; Guo, L. Jay. “Localized micro-scale disruption of cells using laser-generated focused ultrasound.” J. Biophotonics. 2013. DOI: 10.1002/jbio.201200247.

LINK

Laser-generated focused ultrasound (LGFU) was used to disrupt single cells. The LGFU technique uses a carbon nanotube-coated optoacoustic lens to convert laser pulses into focused ultrasound. The sharp focus and high peak pressure of the ultrasound produces microscale disturbances such as micro-jets and secondary shock-waves arising from micro-bubble collapse that can activate single cells for cell harvesting from culture substrates or biomolecule delivery.

 

Frampton, J.P.; Fan, Z.; Simon, A.; Chen, D.; Deng, C.X.; Takayama, S. “Aqueous Two-Phase System Patterning of Microbubbles: Localized Induction of Apoptosis in Sonoporated Cells.” Adv Func Mat.. 2013. DOI: 10.1002/adfm.201203321.

LINK

This new method for studying apoptosis adapts bubbles commonly used for ultrasound imaging to open pores in cell membranes when ultrasound is applied. The most innovative aspect of this new method is our ability to pattern the microbubbles directly on cells. Normally this is very difficult to achieve because microbubbles float in the liquid covering the cells. We overcame this issue by confining the microbubbles in polymer solutions composed of polyethylene glycol and dextran. There are forces associated with the boundary between these two polymer liquids that prevent the microbubbles from escaping. By patterning the microbubbles we can design experiments that test many ultrasound, microbubble or even drug combinations in a single experiment. This will enable high throughput studies of cell death.

 

Kim, S-J; Yokokawa, R.; Takayama, S. “Microfluidic oscillators with widely tunable periods.” Lab Chip.. 2013. DOI: 10.1039/C3LC41415A.

LINK

We present a widely tunable period, constant flow-driven microfluidic oscillator. With the use of tunable external membrane capacitors, the oscillation period spans 4 orders of magnitude from 0.3 s to 4.1 h. We also show that relatively larger external capacitance than internal capacitance of the microfluidic valve is a critical requirement for oscillation.

 

 

Byun, C.K.; Hwang, H.; Choi, W.S.; Yaguchi, T.; Park, J.; Kim, D.; Mitchell, R.J.; Kim, T.; Cho, Y-K; Takayama, S. “Productive chemical interaction between a bacterial microcolony couple is enhanced by periodic relocation.” J. Am. Chem. Soc.. 2013. DOI: 10.1021/ja3094923.

LINK

Aqueous two phase systems (ATPS) allow for spatio-temporal control of bacterial colonies in chemically unrestricted culture. A PEG-Dex ATPS supplemented with magnetic-bead conjugated Dex is used to efficiently relocate Dex-contained bacterial colonies. ATPS-enabled colony relocation increased quorum-sensing markers by moving colonies from a resource-depleted microenvironment to a resource-rich one without disturbing chemical signaling. Computer simulations confirm these observations.

 

 

 

Cheng, M.-C.; Leske, A.T.; Matsuoka, T.; Kim, B. C.; Lee, J.; Burns, M. A.; Takayama, S; Biteen, J.S. “Super-Resolution Imaging of PDMS Nanochannels by Single-Molecule Micelle-Assisted Blink Microscopy.” J. Phys. Chem. B. 2013. DOI: 10.1021/jp307635v.

LINK

Micelle-assisted blink (MAB) microscopy overcomes the difficulty of conventional imaging techniques to measure the nanostrucutre inside devices. This super-resolution imaging technique helps to characterize nanochannel widths, to reveal heterogeneity along channel lengths and between different channels in the same device and to prove biologically relevant information about the nanoenvironment, such as solvent accessibility.

 

2012

Kim, S.J.; Yokokawa, R.; Takayama, S. “Analyzing threshold pressure limitations in microfluidic transistors for sel-regulated microfluidic circuits.” Applied Physics Letters. 2012. DOI: 10.1063/1.4769985.

LINK

Although electric/electronic circuit analogy is prevalent in microfluidic systems, we report that a hydraulic microfluidic membrane-valve is different from electronic transistors: (1) the valve has two significantly different opening and closing threshold pressures, and (2) its opening threshold pressure depends on external parameters like inflow rates and resistances.

 

Matsuoka, T.; Kim, B.C.; Huang, J.; Douville, N.J.; Thouless, M.D.; Takayama, S. “Nanoscale Squeezing in Elastomeric Nanochannels for Single Chromatin Linearization.” Nano Letters. 2012. DOI: 10.1021/nl304063f.

LINK

This nanoscale squeezing procedure generates hydrodynamic flows while also confining the biopolymers into smaller and smaller volumes. The unique features of this technique enable full linearization then trapping of biopolymers such as DNA. The versatility of the method is also demonstrated by analysis of chromatin stretchability and mapping of histone states using single strands of chromatin.

 

Lesher-Perez, S.C.; Frampton, J.P.; Takayama, S. “Microfluidic systems: A new toolbox for pluripotenet stem cells.” Biotechnology Journal. 2012. DOI: 10.1002/biot.201200206.

LINK

This review provides a comprehensive insight into the implications of microfluidics on pluripotent stem cell research, by describing ways in which microfluidic systems can help minimize the gap between conventional in vitro cell culture environments and the in vivo stem cell niche. Our goal was to encompass detailed and specific work applied to pluripotent stem cells cultured in microfluidic environments, and the benefits of using microfluidics as a culturing platform and analysis tool. Additionally, the review touches on existing microfluidic tool sets that have not been applied to pluripotent stem cells, but have potential to enter into this area of research and application, providing more insightful systems and robust techniques.

 

Kim, S.-J.; Lai, D.; Park, J.Y.; Yokokawa, R.; Takayama, S. “Microfluidic Automation Using Elastomeric Valves and Droplets: Reducing Reliance on External Controllers.” Small. 2012. DOI: 10.1002/smll.201200456.

LINK

In recent microfluidic chips, demands for high-throughput analysis with minimal reliance on off-chip controllers are increasing. In this context, we overview elastomeric valve- and droplet-based microfluidic systems: their working principles, limitations of representative components, and the relevant biochemical applications are discussed.

 

Lai, D.; Smith, G.D.; Takayama, S. “Lab-on-a-chip biophotonics: its application to assisted reproductive technologies.” J. Biophotoincs. 2012. DOI: 10.1002/jbio.201200041.

LINK

The integration of biophotonics into microfluidics for lab-on-a-chip (LOC) assisted reproductive technology (ART) is currently a useful tool for non-invasive gamete and embryo quality assessment beyond just simple morphological assessment. As we integrate more advanced biophotonics into LOC devices, the future will bring highly accurate quality assessment and strong predictive power from biophotonics combined with the sensitivity and automation of microlfuidics.

 

Mehta, G.; Hsiao, A.Y.; Ingram, M.; Luker, G.D.; Takayama, S. “Opportunities and challenges for use of tumor spheroids as models to test drug delivery efficacy.” J. Controlled Release. 2012 DOI: 10.1016/j.jconrel.2012.04.045.

LINK

Spheroids offer a physiologically relevant platform for in vitro drug delivery experiments. This review assesses key advantages and challenges, describes experimental techniques, and provides relevant examples of the use of spheroids in drug delivery testing.

 

Park, J.Y; Ahn, D.; Choi, Y.Y; Hwang, C.M.; Takayama, S.; Lee, S.H.; Lee, S.-H. “Surface chemistry modification of PDMS elastomers with boiling water improves cellular adhesion.” J. Sensors and Actuators B. 2012 DOI: 10.1016/j.snb.2012.06.096.

LINK

Although ubiquitous in microfluidics applications, PDMS lacks suitable cell adhesion motifs and therefore requires modification before being used in cell culture assays, typically with ECM proteins. Herein, we describe a simple method for improve the cell adhesion properties of native PDMS using boiling water to generate surface hydroxyl groups. This technique represents a mild, convenient and cheap method for inducing cell adhesion to PDMS microdevices.

 

Yaguchi, T.; Dwidar, M.; Byun, C.K.; Leung, B.; Lee, S.; Cho, Y.-K.; Mitchell, R.J.; Takayama, S. “Aqueous two-phase system-derived biofilms for bacterial interaction studies.” BioMacromolecules. 2012 DOI: 10.1021/bm300500y.

LINK

APTS can be used to selectively pattern bacterial colonies which, over time, form spatially distinct biofilms. Since ATPS printing restricts the diffusion of the bacteria, but not smaller molecules, individual populations are able to communicate with each other. To demonstrate this phenomenon, we show that a B-lactamase producing biofilm can confer ampicillin resistance to neighboring, nonresistant planktonic cells.

 

Wang, J.D.; Douville, N.J.; Takayama, S.; El-Sayed, M. “Quantitative Analysis of Molecular Absorption into PDMS Microfluidic Channels.” Annals of Biomedical Engineering. 2012 DOI: 10.1007/s10439-012-0562-z.

LINK

Many molecules common to cell culture experiments are know to be absorbed by PDMS microchannels during cell culture experiments. We quantify that absorption as a function of the log of a solutes partition coefficient, P. For log(P) < 2.47, absorption was minimal. TiO2 and SiO2 coating was shown to reduce absorption for molecules with log(P) > 2.62.

 

Heo, Y.S.; Cabrera, L.M.; Bormann, C.L.; Smith, G.D.; Takayama, S. “Real time culture and analysis of embryo metabolism using a microfluidic device with deformation based actuation.” Lab Chip. 2012 DOI: 10.1039/C2LC21050A.

LINK

Using a Braille valving and pumping system, we report a microfluidic device for automated, real-time analysis of embryo metabolism. We show simultaneous time-dependent measurements for live mouse blastocyst-stage embryos with pmol/hour sensitivity.

 

Fang, Y.; Frampton, J.P.; Raghavan, S.; Savahi-Kaviani, R.; Luker, G.; Deng, C.X.; Takayama, S. “Rapid Generation fo Multiplexed Cell Cocultures Using Acousitc Droplet Ejection Followed by Aqueous Two-Phase Exclusion Patterning.” Tiss. Eng. C. 2012. DOI: 10.1089/ten.tec.2011.0709.

LINK

Acoustic droplet ejection was used with aqueous two-phase systems to exclusion pattern co-cultures of cells. We used this system to study the chemokinetic responses of cancer cells to surrounding cells. This system will also be useful for patterning other types of cells to study their interactions.

 

 

 

Zamankhan, P.; Helenbrook, B.T.; Takayama, S.; Grotberg, J.B. “Steady motion of Bingham liquid plugs in two-dimensional channels.” J Fluid Mech. 2012. DOI: 10.1017/jfm.2011.43.

LINK

Using numerical analysis, we model non-Newtonian (Bingham) fluid plug behavior in 2D channels. This research has implications for various lung pathologies.

 

Hsiao, A.Y.; Tung, Y.-C.; Qu, X.; Patel, L.R.; Pienta, K.J.; Takayama, S. “384 hanging drop arrays give excellent z-factors and allow versatile formation of co-culture spheroids.” Biotechnology and Bioengineering 2012. DOI: 10.1002/bit.24399.

LINK

A previously reported 384 hanging droplet spheroid culture platform was shown to perform well in fluorescence and colorimetric-based assays. We also demonstrate spheroid transfer and retrieval, as well as sequential addition of cell types for concentric, co-culture applications.

 

Ray; P.; Lewin, S.A.; Mihalko, L.A.; Lesher-Perez, S.C.; Takayama, S.; Luker, K.E.; Luker, G.D. “Secreted CXCL12 (SDF-1) Forms Dimers under Physiologic Conditions.” Biochem. J. 2012. DOI: 10.1042/BJ20111341.

LINK

This paper showed that CXCL12 was secreted from cells both in monomer and dimer forms, and that in three-dimensional culture systems homodimerization occurred as well, a characteristic not achieved within the two-dimensional cultures. Furthermore this paper demonstrated that the monomer and dimer CXCL12 populations preferentially activated different CXCR4 signalling pathways and produced differential migratory responses, while CXCL12 monomer was only significantly sequestered by CXCR7.

 

Moraes, C.; Mehta, G.; Lesher-Perez, S.C.; Takayama, S. “Organs-on-a-Chip: A Focus on Compartmentalized Microdevices.” Annals of Biomedical Engineering 2012.. DOI: 10.1007/s10439-011-0455-6.

LINK

Microengineering techniques have yield significant advances in the biomedical sciences. Designing micro-scale systems to simulate entire organs would be a powerful experimental tool, increasing relevance while decreasing costs and complexity. This article surveys and discusses recently reported organ-on-a-chip systems.

 

Hsiao, A.Y.; Tung, Y-C; Kuo, C-H, Mosadegh, B.; Bedenis, R.; Pienta, K.J.; Takayama, S. “Micro-ring structures stabilize microdroplets to enable long term spheroid culture in 384 hanging drop array plates.” Biomed. Microdev. 2012. DOI: 10.1007/s10544-011-9608-5.

LINK

Micro-ring structures were used to enhance the stability of 384 well hanging drop assay plate. This new design was shown to be more resistant against mechanical perturbations than previous methods and reliably enabled sustained cell culture for over three weeks.

 

Smith, G.D.; Takayama, S.; Swain, J.E. “Rethinking In Vitro Embryo Culture: New Developments in Culture Platforms and Potential to Improve Assisted Reproductive Technologies.” Biol. Reprod. 2012.. DOI:10.1095/biolreprod.111.095778.

LINK

Research on in vitro embryo development has focused on traditionally focused on soluble factors. This review considers how other factors (such as temporal or mechanical cues) may influence embryo development.

 

2011

Kim,S.-J.; Yokokawa, R.; Lesher-Perez, S.C.; Takayama, S. “Constant flow-driven microfluidic oscillator for different duty cycles.” Anal Chem 2011. DOI: 10.1021/ac202866b.

LINK

We designed a normally closed 3-terminal valve constant flow-driven oscillator, building on our previous 4-valve design, this switch to a more electronic circuit analogous design, allowed us to achieve different duty cycles within our device. This paper further characterized the necessary pressures to produce oscillatory behavior within our devices, as well as demonstrated this system to be capable of periodic stimulation/treatment of cultured cells.

 

White, J.B.; Takayama, S. “Receptor differential activation and cooperativity better explain cellular preference for different chemoattractant gradient shapes in an EGFR system.” Integr. Biol. 2011. DOI:10.1039/C1IB00040C.

LINK

This paper describes a model that explains how cells can fine-tune their migratory response to chemokines. Receptors, especially EGFR, have much different signaling characteristics depending on their degree of oligomerization. We demonstrate how receptor cooperativity and oligomerization can change a cell’s migration abilities in vitro which could have implications in how we study cancer metastasis and autoimmunity in vitro.

 

Lai, D.; Frampton, J.P.; Sriram, H.; Takayama, S. “Rounded multi-level microchannels with orifices made in one exposure enable aqueous two-phase system droplet microfluidics.” Lab Chip 2011. DOI:10.1039/C1LC20560A.

LINK

A one-step exposure to fabricate multi-layer channels for Aqueous Two-Phase System droplets with the lowest interfacial tension to date.

 

Mosadegh, B.; Bersano-Begey, T.; Park, J.Y.; Burns, M.A.; Takayama, S. “Next-generation integrated microfluidic circuits.” Lab Chip 2011. DOI: 10.1039/C1LC20387H.

LINK

This paper provides a brief overview of microfluidic devices that allow for increased on-chip control of fluid flow through embedded elastomer valves. Parallel instruction, serial instruction, and embedded instruction control schemes are specifically addressed.

 

Frampton, J.P.; Lai, D.; Sriram, H.; Takayama, S. “Precisely targeted delivery of cells and biomolecules within microchannels using aqueous two-phase systems.” Biomedical Microdevices 2011. DOI: 10.1007/s10544-011-9574-y.

LINK

Small molecule delivery in microfluidic channels has previously been limited by diffusion of the molecules across liquid-liquid interfaces. Aqueous two-phase technology is a biocompatible method that allows for improved spatial resolution when delivering cells, proteins, or small molecules.

 

Park, J.Y.; White, J.B.; Walker, N.; Kuo, C.H.; Cha, W.; Meyerhoff, M.E.; Takayama, S. “Response of endothelial cells to extremely slow flows.” Biomicrofluidics 2011. DOI: 10.1063/1.3576932.

LINK

This paper describes the effects of extremely slow fluid flow on endothelial cells. Traditional flow studies examine the effects of flow with shear greater than 0.1 dyne/cm2, we utilize an osmotic pump to achieve 10-1000 times smaller shear which can have implications in angiogenesis and developmental biology.

 

Douville, N.J.; Li, Z.; Takayama, S.; Thouless, M.D. “Fracture of metal coated elastomers.” Soft Matter 2011. DOI: 10.1039/C1SM05140G.

LINK

Strain-induced cracks in gold-coated elastomeric PDMS slabs were examined. These cracks were orders of magnitude deeper than the gold film. We suggest that cracking of the PDMS substrate occurs to release residual energy from failure of the gold film.

 

Tavana, H.; Kaylan, K.; Bersano-Begley, T.: Luker, K.E.; Luker, G.D.; Takayama, S. “Rehydration of polymeric, aqueous, biphasic system facilitates high throughput cell exclusion patterning for cell migration studies.” Advanced Functional Materials 2011. DOI: 10.1002/adfm.201002559.

LINK

Using aqueous two-phase systems for non-contact cell exclusion printing, we design a novel, high-throughput method for cell migration studies. We validate our “gap migration” platform using known cytoskeletal inhibitors.

 

 

Jovic, A.; Wade, S.M.; Miyawaki, A.; Neubig, R.R.; Linderman, J.J.; Takayama, S. “Hi-Fi transmission of periodic signals amid cell-to-cell variability.” Molecular BioSystems 2011. DOI: 10.1039/c1mb05031a.

LINK

This paper combines experimental and theoretical approaches to high fidelity develop techniques for monitoring changes in intracellular calcium oscillations due to extracellular signals (such as G-protein coupled receptor activation).

 

 

Tavana, H.; Mosadegh, B.; Zamankhan, P.; Grotberg, J.B.; Takayama, S. “Microprinted Feeder cells guide embryonic stem cell fate.” Biotechnology and Bioengineering 2011. DOI: 10.1002/bit.23190.

LINK

A non-contact, microprinting technique allows for controlled patterning of feeder cell arrays of different sizes on a gel substrate. We demonstrate that feeder cell type can direct fate of overlaid mouse embryonic stem cells.

 

Thouless, M.D.; Li, Z.; Douville, N.J.; Takayama, S. “Periodic cracking of films supported on compliant substrates.” J. Mechanics and Physics of Solids 2011. DOI:10.1016/j.jmps.2011.04.009.

LINK

Strain can cause patterns of parallel cracks to form in rigid films and their soft substrates. This paper modifies a linear-elastic fracture model to explain this phenomenon.

 

 

 

Tavana, H.; Zamankhan, P.; Christensen, P.J.; Grotberg, J.B.; Takayama, S. “Epithelium damage and protection during reopening of occluded airway in a physiologic microfluidic pulmonary airway model.” Biomed. Microdev. 2011. DOI: 10.1007/s10544-011-9543-5.

LINK

Using a microfluidic device, we study the response of lung airway epithelial cells to stresses generated from repeated exposure to liquid plugs. Addition of surfactant rescues cells from plug-induced cell damage and death. Mathematical modeling confirms the experimental observations.

 

Didwania, M.; Didwania, A.; Mehta, G.; Basak, G.W; Yasukawa, S.; Takayama, S.; de Necochea-Campion, R.; Srivastava, A.; Carrier, E. “Artificial Hematopoietic Stem Cell Niche: Bioscaffolds to Microfluids to Mathematical Simulations.” Curr. Top. Med. Chem 2011.

LINK

Two recreate an artificial, in vivo-like niche for hematopoietic stem cells, it is necessary to consider the scaffold, the cells themselves, and soluble factors. We describe the states of the art for these three areas and include a mathematical model to aid in design and optimization of an artificial bioreactor.

 

Tavana, H.; Takayama, S. “Aqueous biphasic microprinting approach to tissue engineering.” Biomicrofluidics 2011, 5. DOI: 10.10631/1.3516658.

LINK

Recent developments have shown aqueous two-phase printing (ATPS) to be a valuable tool for non-contact printing of biomaterials. Since both parts of an ATPS are completely aqueous, yet immiscible, this technique is ideal for spatially patterning delicate molecules or cells without compromising substrate integrity or cell viability.

 

Chantiwas, R.; Park, S.; Soper, S. A.; Kim, B.C.; Takayama, S.; Sunkara, V.; Hwang, H.; Cho, Y.-K. “Flexible Fabrication and Applications of Polymer Nanochannels and Nanoslits.” Chem. Soc. Rev. 2011. DOI: 10.1039/C0CS00138D.

LINK

This critical review provides an overview of recent advances in polymer-based nanofluidics.

 

 

Torisawa, Y; Mosadegh, B.; Cavnar, S. P.; Ho, M.; Takayama, S. “Transwells with Microstamped Membranes Produce Micropatterned 2D and 3D Co-cultures” Tissue Eng Part C 2011, 17, 61-67.

LINK

Hydrodynamic forces created by a microcontact printed PDMS layer are used to guide cell patterns on the underside of a Transwell co-culture insert. Through co-culture experiments, this paper shows that HepG2 cells inhibit mouse embryonic fibroblast Sox17 formation via direct cell-cell contact and cellular signaling mechanisms.

 

 

Douville, N. J.; Zamankhan, P.; Tung, Y.-C.; Li, R.; Vaughan, B. L.; White, J.; Grotberg, J. B.; Takayama, S. “Combination Fluid and Solid Mechanical Stresses Contribute to Cell Death and Detachment in a Microfluidic Alveolar Model” Lab Chip 2011 11, 609-619.

LINK

This paper describes the importance of mechanical stretch and fluid mechanical stresses in lung injury. In diseased lungs, edematous liquid can fill the airways and impart injurious shear and pressure on alveolar cells; we developed a device to investigate the under-studied contribution of these stresses to alveolar cell death and delamitation.

 

Mosadegh, B.; Tavana, H.; Lesher-Perez, S.C.; Takayama, S.
“Patterned deactivation of oxidized polydimethylsiloxane surface for high-density fabrication of normally-closed microfluidic valves” Lab Chip 2011, 11, 734-742. DOI: 10.1142/S0219519410003617.

LINK

Plasma oxidation of PDMS is ubiquitous in microfluidic research. Plasma-induced changes in surface chemistry can be reversed in a spatially-controlled manner by microcontact printing with a second PDMS stamp. Applications in valving and “open microfluidics” are demonstrated.

 

Tung, Y.-C.; Hsiao, A.Y.; Allen, S.; Torisawa, Y.; Ho, M.; Takayama, S. “High-throughput spheroid formation, culture, and anti-cancer drug testing using a 384 hanging drop array.” Analyst 2011, 136, 473-478. DOI:10.1039/C0AN00609B.

LINK

This paper describes a 384-well format hanging drop cell culture plate that allows for 3D spheroid formation and culture using existing high-throughput screening instruments. Using this platform, we demonstrated anti-cancer drug testing and found differential response of cells cultured in 2D versus 3D for drugs with different modes of action. This user-friendly 3D culture plate provides a simple way to obtain biological insights that are often lost in 2D monolayer cultures.

 

2010

Jovic, A.; Howell, B.; Cote, M.; Wade, S. M.; Mehta, K.; Miyawaki, A.; Neubig, R. R.; Linderman, J. J.; Takayama, S.
“Phase-Locked Signals Elucidate Circuit Architecture of an Oscillatory Pathway” PLoS Comp Biol. 2010, 6(20).

Park, J. Y.; Morgan, M.; Sachs, A. N.; Samorezov, J.; Teller, R.; Shen, Y.; Pienta, K. J.; Takayama, S.
“Single cell trapping in larger microwells capable of supporting cell spreading and proliferation” Microfluid. Nanofluid. 2010, 8, 263-268.

Chueh, B.-H.; Zheng, Y.; Torisawa, Y.; Ge, C.; Hsiong, S.; Huebsch, N.; Franceschi, R.; Mooney, D. J.; Takayama, S.
“Patterning of Alginate Hydrogel Using Light-Directed Release of Caged Calcium in a Microfluidic Device” Biomed. Microdev. 2010, 12, 145-151. DOI 10.1007/s10544-009-9369-6.

Heo, Y.; Cabrera, L. M.; Bormann, C. L.; Shah, C. T.; Takayama, S.; Smith, G. D.
“Dynamic microfunnel culture enhances embryo development and pregnancy rates” Hum Reprod 2010, 25, 613-622.

Tavana, H.; Kuo, C.-H.; Lee, Q. Y.; Mosadegh, B.; Huh, D.; Christensen, P. J.; Grotberg, J. B.; Takayama, S.
“Dynamics of Liquid Plugs of Buffer and Surfactant Solutions in a Micro-Engineered Pulmonary Airway Model” Langmuir 2010, 26, 3744-3752.

Tavana, H.; Jovic, A.; Mosadegh, B.; Yi, L. Q.; Liu, X.; Luker, K. E.; Luker, G. D.; Weiss, S. J.; Takayama, S.
“Aqueous Nanodrops in Aqueous Media”. BIOforum Europe, 2010, 1-2, 17-19.

Douville, N. J.; Tung, Y.-C.; Li, R.; Wang, J. D.; El-Sayed, M. E. H.; Takayama, S.
“Fabrication of Two-Layered Channel System with Embedded Electrodes to Measure Resistance Across Epithelial and Endothelial Barriers” Anal. Chem. 2010, 82, 2505-2511.

Cha, W.; Tung, Y.-C.; Meyerhoff, M. E.; Takayama, S.
“Patterned electrode-based amperometric gas sensor for direct nitric oxide detection within microfluidic devices” Anal. Chem. 2010, 82, 3300-3305.

Raghavan, S.; Lam, M. T.; Foster, L. L.; Gilmont, R. R.; Somara, S.; Takayama, S.; Bitar, K. N.
“Bioengineered three-dimensional physiological model of colonic longitudinal smooth muscle in vitro” Tissue Eng Part C: Methods 2010, 16, 999-1009.

Mills, K. L.; Huh, D.; Takayama, S.; Thouless, MD.
“Instantaneous fabrication of arrays of normally closed, adjustable, and reversible nanochannels by tunnel cracking” Lab Chip 2010, 10, 1627 – 1630.

Mosadegh, B.; Kuo, C.-H.; Tung, Y.-C.; Torisawa, Y.; Bersano-Begey, T.; Tavana, H.; Takayama, S.
“Integrated elastomeric components for autonomous regulation of sequential and oscillatory flow switching in microfluidic devices” Nature Physics 2010, 6, 433-437.

Tavana, H.; Mosadegh, B.; Takayama, S.
“Polymeric Aqueous Biphasic Systems for Non-Contact Cell Printing on Cells: Engineering Heterocellular Embryonic Stem Cell Niches” Adv Mater 2010, 22, 2628-2631.

Dixon, A.; Takayama, S.
“Guided Corona Generates Wettability Patterns that Selectively Direct Cell Attachment Inside Closed Microchannels” Biomed. Microdev. 2010, 12, 769-775.

Park, J.Y.; Takayama, S.; Lee, S.-H.
“Regulating microenvironmental stimuli for stem cells and cancer cells using microsystems” Integr. Biol. 2010, 2, 229-240.

Mosadegh, B.; Agarwala, M.; Torisawa, Y.; Takayama, S.
“Simultaneous Fabrication of High-Density PDMS Through-Holes for Three-Dimensional Microfluidic Applications” Lab Chip 2010, 10, 1983-1986.

Tkaczyk, A. H,; Tkaczyk, E. R.; Norris, T. B.; Takayama, S.
“Microfluidic Droplet Consistency Monitoring and Cell Detection via Laser Excitation” JMMB. 2010, DOI: 10.1142/S0219519410003617.

Ghim, C.-M.; Lee, S. K.; Takayama, S.; Mitchell, R. J.
“The Art of Reporter Proteins in Science: Past, Present and Future Applications” BMB Reports 2010, 43, 451-460.

Yaguchi, T.; Lee, S.; Choi, W. S.; Kim, D.; Kim, T.; Mitchell, R. J.; Takayama, S.
“Micropatterning Bacterial Suspensions Using Aqueous Two Phase Systems” Analyst 2010, 135, 2848-2852.

Mosadegh, B.; Agarwal, M; Tavana, H.; Bersano-Begey, T.; Torisawa, Y.-S.; Morell, M.; Wyatt, M. J.; O’Shea, K. S.; Barald, K. F.; Takayama, S.
“Uniform Cell Seeding and Generation of Overlapping Gradient Profiles in a Multiplexed Microchamber Device with Normally-Closed Valves” Lab Chip 2010, 10, 2959 – 2964.

Torisawa, Y.; Mosadegh, B.; Bersano-Begey, T.; Steele, J. M.; Luker, K. E.; Luker, G. D.; Takayama, S.
“Microfluidic platform for chemotaxis in gradients formed by source-sink cells” Integr Biol 2010, 2, 680-686.

Huang, N.-T.; Truxal, S. C.; Tung, Y.-C.; Hsiao, A. Y.; Luker, G. D.; Takayama, S.; Kurabayashi, K.
“Muliplexed spectral signature detection for microfluidic color-coded bioparticle flow” Anal. Chem. DOI: 10.1021/ac102240g.

2009

G. Mehta; J. Lee; W. Cha; Y.-C. Tung; J. J. Linderman; S. Takayama
“Hard Top-Soft Bottom Microdevices for Hypoxia and Braille Actuation” Analytical Chemistry 2009, 81(10), 3714-22.

G. Mehta; Y. Torisawa; S. Takayama
“Engineering Cellular Microenvironments with Microfluidics” Biological Applications of Microfluidics F. A. Gomez (Editor), John Wiley and Sons 2008, 87-114.

Tavana, H.; Jovic, A.; Mosadegh, B.; Yi. L.Q.; Liu, X.; Luker, K. E.; Luker, G. D.; Weiss, S. J.; Takayama, S.
“Nanolitre liquid patterning in aqueous environments for spatially defined reagent delivery to mammalian cells” Nature Materials 2009, 8, 736-741.

Huh, D.; Kuo, C.-H.; Grotberg, J. B.; Takayama, S.
“Gas-liquid two-phase flow patterns in rectangular polymeric microchannels: effect of surface wetting properties” New J. Physics 2009, 11, 075034.

Zheng, Y.; Fujioka, H.; Bian, S.; Torisawa, Y.; Huh, D.; Takayama, S.; Grotberg, J. B.
“Liquid Plug Propagation in Flexible Microchannels – a Small Airway Model” Phys. Fluids 2009, 21, 071903.

Mehta, K.; Mehta, G.; Takayama, S.; Linderman, J. J.
“Quantitative Inference of Cellular Parameters from Microfluidic Cell Culture Systems for Tissue Engineering” Biotechnol. Bioeng. 2009, 103, 966-974.

Huang N.T., Truxal S.C., Tung Y.-C., Hsiao A., Takayama S., Kurabayashi K.
“High-speed tuning of visible laser wavelength using a nanoimprinted grating optical tunable filter” Appl Phys Lett 2009, 21, 211106.

Torisawa Y., Mosadegh B, Luker G.D., Morell M., O’Shea K.S., Takayama S.
“Microfluidic Hydrodynamic Cellular Patterning for Spheroid Co-culture” Integr Biol 2009, 1, 649-654.

Villa-Diaz, L.G.; Torisawa, Y.; Uchida, T.; Ding, J.; Noguiera-de-Souza, N. C.; O’Shea, K. S.; Takayama, S.; Smith, G. D.
“Microfluidic culture of single human embryonic stem cell colonies” Lab Chip 2009, 9, 1749-1755.

Lam, M. T.; Huang, Y.-C.; Birla, R. K.; Takayama, S.
“Microfeature guided skeletal muscle tissue engineering for highly organized 3-dimensional free-standing constructs” Biomaterials 2009, 30, 1150-1155.

Uchida, T.; Mills, K. L.; Tung, Y.-C.; Thouless, M.D.; Takayama, S.
“External Compression-induced Fracture Patterning on the Surface of Poly(dimethylsiloxane) Cubes and Microspheres” Langmuir 2009, 25, 3102?3107.

Song, J. W.; Cavnar, S. P.; Walker, A. C.; Luker, K. E.; Gupta, M.; Tung, Y.-C.; Luker, G. D.; Takayama, S.
“Microfluidic Endothelium for Studying the Intravascular Adhesion of Metastatic Breast Cancer Cells?” PLos One 2009, 4, e5756.

Tavana, H.; Huh, D.; Grotberg, J. B.; Takayama, S.
“In Vitro Microfluidic Human Pulmonary Airway” Lab. Medicine 2009, 4, 203-209

Hsiao, A.; Torisawa, Y.; Tung, Y.-C.; Sud, S.; Taichman, R. S.; Pienta, K. J.; Takayama, S.
“Microfluidic system for formation of PC-3 prostate cancer co-culture spheroids” Biomaterials 2009, 30, 3020-3027.

Jovic, A.; Howell, B.; Takayama, S.
“Timing is Everything: Using Fluidics to Understand the Role of Temporal Dynamics in Cellular Systems” Microfluidics Nanofluidics 2009, 81, 3714-3722.

Shen, Y.-C.; Li, D.; Al-Shoaibi, A.; Bersano-Begey, T.; Chen, H.; Ali, S.; Flak, B.; Perrin, C.; Winslow, M.; Shah, H.; Ramamurthy, P.; Schmedlen, R. H.; Takayama, S.; Barald, K. F.
“Student Team in a University of Michigan Biomedical Engineering Design Course Constructs a Microfluidic Bioreactor for Studies of Zebrafish Development” Zebrafish 2009, 6, 201-213.

2008

Halpern, D.; Fujioka, H.; Takayama, S.; Grotberg, J. B.
“Liquid and surfactant delivery into pulmonary airways” Respir. Physiol. Neurobiol. 2008, 163, 222-231.

Mills, K. L.; Zhu, X.; Takayama, S.; Thouless, M. D.
“The mechanical properties of a surface-modified layer on poly(dimethylsiloxane)” J. Mater. Res. 2008, 23, 37-48.

Lam, M.T.; Clem, W.; Takayama, S.
“Dynamic microtopography for reversible on-demand cell alignment” Biomaterials 2008, 29, 1705-1712.

Kamotani, Y.; Bersano-Begey, T.; Kato, N.; Tung, Y.-C.; Huh, D.; Song, J. W.; Takayama, S.
“Individually Programmable Cell Stretching Microwell Arrays Actuated by a Braille Display” Biomaterials 2008, 29, 2636-2655.

Fan, C. Y.; Tung, Y.-C.; Takayama, S.; Meyhofer, E.; Kurabayashi, K.
“Electrically Programmable Surfaces for Configurable Patterning of Cells” Adv. Mater. 2008, 20, 1418-1423.

Douville, N.; Huh, D.; Takayama, S.
“DNA linearization through confinement in nanochannels” Anal. Bioanal. Chem. 2008, 391, 2395-2409.

Chen, H.; Gu, W.; Cellar, N.; Takayama, S.; Kennedy, R.; Meiners, J.-C.
“Electromechanical properties of pressure-actuated PDMS microfluidic push-down valves” Anal. Chem. 2008, 80, 6110-6113.

Tavana, H.; Huh, D.; Grotberg, J. B.; Takayama, S.
“Pulmonary Airways on a Chip” BIOforum Europe 2008, 7-8, 14-16.

Fujioka, H.; Takayama, S.; Grotberg, J. B.
“Unsteady propagation of a liquid plug in a liquid-lined straight tube” Phys. Fluids 2008, 20, 062104.

2007

Torisawa, Y.; Chueh, B.-H.; Huh, D.; Ramamurthy, P.; Roth, T. M.; Barald, K. F.; Takayama, S.
“Efficient Synchronous Formation of Uniform-Sized Embryoid Bodies Using a Compartmentalized Microchannel Device” Lab Chip 2007, 7, 770-776.

Smith, G. D.; Takayama, S.
“Gamete and embryo isolation and culture using microfluidics”Theriogenology 2007, 68, Suppl. 1 S190-S195.

Mehta, G.; Kiel, M. J.; Lee, J. W.; Kotov, N.; Linderman, J. J.; Takayama, S.
“Polyelectrolyte-Clay-Protein Layer Films on Microfluidic PDMS Bioreactor Surfaces for Primary Murine Bone Marrow Cultures”Adv. Funct. Mater. 2007, 17, 2701-2709.

Tung, Y. C.; Torisawa, Y.; Futai, N.; Takayama, S.
“Small volume low mechanical stress cytometry using computer-controlled Braille display microfluidics”Lab Chip 2007, 7, 1497-1503.

Inamdar, M. V.; Kim, T.; Chung, Y.-K.; Was, A.; Xiang, X.; Wang, C.-W.; Takayama, S.; Lastoskie, C. M.; Thomas, F. I. M.; Sastry, A. M.
“Assessment of Sperm Chemokinesis with Exposure to Jelly Coats of Sea Urchin Eggs and Resact: A Microfluidic Experiment, and Numerical Study”J. Exp. Biol. 2007, 210, 3805-3820.

Huh, D; Fujioka, H.; Tung, Y.-C.; Futai, N.; Paine, R.; Grotberg, J. B.; Takayama, S.
“Acoustically Detectable Cellular-Level Lung Injury Induced by Fluid Mechanical Stresses in Microfluidic Airway Systems”J. Proc. Natl. Acad. Sci. U.S.A. 2007, 104, 18886-18891.

Huh, D.; Mills, K.L.; Zhu, X.Y.; Burns, M.A.; Thouless, M.D.; Takayama, S.
“Tuneable elastomeric nanochannels for nanofluidic manipulation” Nature Materials 2007, 6, 424-428.

Chueh, B.-H.; Huh, D.; Kyrtsos, C.R.; Houssin, T.; Futai, N.; Takayama, S.
“Leakage-free bonding of porous membranes into layered microfluidics array systems” Analytical Chemistry 2007, 79, 3504-3508.

Mehta, G.; Mehta, K.; Sud, D.; Song, J.W.; Bersano-Begey, T.; Futai, N.; Heo, Y.S.; Mycek, M.-A.; Linderman, J.J.; Takayama, S.
“Quantitative measurement and control of oxygen levels in microfluidic poly(dimethylsiloxane) bioreactors during cell culture” Biomedical Microdevices 2007, 9, 123-134.

Huh, D.; Bahng, J.H.; Ling, Y.B.; Wei, H.-H.; Kripfgans, O.D.; Fowlkes, J.B.; Grotberg, J.B.; Takayama, S.
“Gravity-driven microfluidic particle sorting device with hydrodynamic separation amplification” Analytical Chemistry 2007, 79, 1369-1376.

Gu, W.; Chen, H.; Tung, Y.-C.; Meiners, J.-C.; Takayama, S.
“Multiplexed hydraulic valve actuation using ionic liquid filled soft channels and Braille displays” Applied Physics Letters 2007, 90, Art. No. 033505.

Heo, Y.S.; Cabrera, L.M.; Song, J.W.; Futai, N.; Tung, Y.-C.; Smith, G.D.; Takayama, S.
“Characterization and resolution of evaporation-mediated osmolality shifts that constrain microfluidic cell culture in poly(dimethylsiloxane) devices” Analytical Chemistry 2007, 79, 1126-1134.

2006

Calderon, A. J.; Heo, Y. S.; Huh, D.; Futai, N.; Takayama, S.; Fowlkes, J. B.; Bull, J. L.
“A Microfluidic Model of Bubble Lodging in Microvessel Bifurcations” Appl. Phys. Lett. 2006, 89, Art. No. 244103.

Sud, D.; Mehta, G.; Mehta, K.; Linderman, J. J.; Takayama, S.; Mycek, M.-A.
“Optical Imaging in Microfluidic Bioreactors Enable Oxygen Monitoring for Continuous Cell Culture” Opt. Lett. 2006,11, Art. No. 050504.

Lam, M. T.; Sim, S.; Zhu, X.; Takayama, S.
“The Effect of Continuous Wavy Micropatterns on SIlicone Substrates on the ALignment of Skeletal Muscle Myoblasts and Myotbues” Biomaterials. 2006 27, 4340-4347.

Futai, N.; Naruse, K.; Smith, G. D.; Takayama, S.
“Microfluidic In Vitro Fertilization” Igaku No Ayumi. 2006, 218, 159-163.

Wu, J. M.; Chung, Y.; Belford, K. J.; Smith, G. D.; Takayama, S.; Lahann, J.
“A surface-modified sperm sorting device with long-term stability” Biomed. Microdev. 2006, 8, 99-107.

Suh, R. S.; Zhu, X.; Phadke, N.; Ohl, D. A.; Takayama, S.; Smith, S. D.
“In Vitro Fertilization Within Microfluidic Channels Requires Lower Total Numbers and Lower Concetrations of Spermatozoa” Hum. Reprod. 2006, 21, 477-483.

Futai, N.; Gu, W; Song, J. W.; Takayama, S.
“Handheld Recirculation System and Customized Media for Microfluidic Cell Culture” Lab Chip. 2006, 6, 149-154.

2005

Suh, R. S.; Takayama, S.; Smith, G. D.
“Microfluidic Applications for Andrology” J. Androl. 2005, 664-670

Zhu, X.; Mills, K. L.; Peters, P. R.; Bahng, J. H.; Liu E. H.; Shim, J.; Naruse, K.; Csete, M. E.; Thouless, M. D.; Takayama, S.
“Fabrication of Reconfigurable Protein Matrices by Cracking” Nat. Mater. 2005, 4, 403-406.

Song, J. W.; Gu, W.; Futai, N.; Warner, K. A.; Nor, J. E.; Takayama, S.
“Computer-Controlled Microcirculatory System for Endothelial Cell Culture and Shearing” Anal. Chem. 2005, 77, 3993-3999.

Huh, D.; Kamotani, Y.; Grotberg, J. B.; Takayama, S.
“Microfluidics for Flow Cytometric Analysis of Cells and Particles” Physiol. Meas. 2005, R73-R98.

2004

Gu, W.; Zhu, X.; Futai, N.; Cho, B. S.; Takayama, S.
“Computerized Microfluidic Cell Culture Using Elastomeric Channels and Braille Displays” Proc. Natl. Acad. Sci. U.S.A. 2004, 101, 15861-15866.

Futai, N.; Gu, W.; Takayama, S.
“Rapid Prototyping of Microstructures with Bell-Shaped Cross-Sections and Its Application to Deformation-Based Microfluidic Valves” Adv. Mater. 2004, 16, 1320-1323.

Zhu, X.; Chu, L. Y.; Chueh, B.-H.; Shen, M.; Hazarika, B.; Phadke, N.; Takayama, S.
“Arrays of Horizontally-Oriented Mini-Reservoirs Generate Steady Microfluidic Flows for Continuous Perfusion Cell Culture and Gradient Generation” Analyst 2004, 1026-1031.

Zhu, X.; Bersano-Begey, T. F.; Takayama, S.
“Nanomaterials for Cell Engineering” Encyclopedia of Nanoscience and Nanotechnology, Ed. Nalwa, H. S., 2004, 6, 857-878.

2003

Takayama, S.; Ostuni, E.; LeDuc, P. Naruse, K.; Ingber, D. E.; Whitesides, G. M.
“Selective Chemical Treatment of Cellular Microdomains Using Multiple Laminar Streams” Chem. Biol., 2003, 10, 123-130.

Shim, J.; Bersano-Begey, T. F.; Zhu, X.; Tkaczyk, A.; Linderman, J.J.; Takayama, S.
“Micro- and Nanotechnologies for Studying Cellular Function” Curr. Top. Med. Chem., 2003, 3, 687-703.

Cho, B.; Schuster, T.G.; Zhu, X.; Chang, D.; Smith, G.D.; Takayama, S.
“A Passively-Driven Integrated Microfluidic System for Separation of Motile Sperm” Anal. Chem. 2003, 75, 1671-1675.

Schuster, T.G.; Cho, B.; Keller, L. M.; Takayama, S.; Smith, G. D.
“Isolation of Motile Sperm From Semen Samples Using Microfluidics” Reproduc. Biomed. Online. 2003, 7, 75-81.

Suh, R. S.; Phadke, N.; Ohl, D. A.; Takayama, S.; Smith, G. D.
“Rethinking Gamete/Embryo Isolation and Culture with Microfluidics” Hum. Reprod. Update 2003, 9, 451-461.

Lim, D.; Kamotani, Y.; Cho, B.; Mazumder, J.; Takayama, S.
“Fabrication of Microfluidics Mixers and Artificial Vasculatures Using a High-Brightness Diode-Pumped Nd:YAG Laser Direct Write Method” Lab Chip 2003, 3, 318-323.

Huh, D.; Tkaczyk, A.H.; Bahng, J.-H.; Chang, Y.; Wei, H.-H.; Grotberg, J.B.; Kim, C.-J.; Kurabayashi, K.; Takayama, S.
“Reversible Switching of High-Speed Air-Liquid Two-Phase Flows Using Electrowetting-Assisted Flow-Pattern Change” J. Am. Chem. Soc. 2003, 125, 14678-14679.

2002

Jiang, X.; Takayama S.; Qian, X.; Ostuni, E.; Wu, H.; Bowden, N.; LeDuc, P.; Ingber, D. E.; Whitesides, G. M.
“Controlling Mammalian Cell Spreading and Cytoskeletal Arrangement with Conveniently Fabricated Continuous Wavy Features on Poly(dimethylsiloxane)” Langmuir, 2002; 18, 3273.

Huh, D; Tung, Y-C; Wei, H.-H.Grotberg, J.B.; Skerlos, S.J.; Kurabayashi, K.; Takayama, S.
“Use of Air-Liquid Two-Phase Flow in Hydrophobic Microfluidic Channels for Disposable Flow Cytometers” Biomed. Microdev. 2002,4, 141-149.

Sawano, A.; Takayama, S.; Matsuda, M.; Miyawaki, A.
“Lateral Propagation of EGF Signaling after Local Stimulation Is Dependent on Receptor Density” Dev. Cell, 2002, 3, 245-257.

2001

Takayama, S.; Ostuni, E.; Qian, X.; McDonald, J. C.; Jiang, X.; LeDuc, P.; Wu, M.-H.; Ingber, D. E.; Whitesides, G. M.
“Topographical Micropatterning of Poly(dimethylsiloxane) Using Laminar Flows of Liquids in Capillaries” Adv. Mater. 2001, 13, 570-574.

Holmlin, R. E.;Chen, X.; Chapman, R.; Takayama, S.; Whitesides, G. M.
“Zwitterionic SAMs that Resist Nonspecific Adsorption of Protein from Aqueous Buffer” Langmuir, 2001, 17, 2841-2850.

Takayama, S.; Ostuni, E.; LeDuc, P. Naruse, K.; Ingber, D. E.; Whitesides, G. M.
“Laminar Flows: Subcellular Positioning of Small Molecules” Nature, 2001, 411, 1016.

Whitesides, G.M.; Ostuni, E.; Takayama, S.; Jiang, X
“Soft Lithography for Biology” Ann. Rev. Biomed.Eng. 2001, 3, 335-373.

Ostuni, E; Chapman, R. G.; Holmlin, R. E.; Takayama, S.; Whitesides, G. M.
“A Survey of Structure-Properety Relationships of Surfaces that Resist the Adsorption of Proteins” Langmuir, 2001, 17, 5605-5620.

2000

Takayama, S.; Chapman, R. G.; Kane, R. S.; Whitesides, G. M.
“Patterning Cells and their Environment” Book chapter in Principles of Tissue Engineering, 2nd Ed. Lanza, R.; Langer, R.; Vacanti, J. 2000, 209-220.

Chapman, R. G.; Ostuni, E.; Takayama, S.; Holmlin, R. E.; Yan, L.; Whitesides, G. M.
“Surveying for Surfaces that Resist the Adsorption of Proteins” J. Am. Chem. Soc. 2000, 122, 8303-8304.

Kenis, P. J. A.; Ismagilov, R. F.; Takayama, S.; Whitesides, G. M.; Li, S; White, H. S.
“Microfabrication Inside Microchannels using Fluid Flow” Acc. Chem. Res. 2000, 33, 841-847.

1999

Takayama, S.; Lee, S. T.; Hung, S.-C.; Wong, C.-H.
“Designing Enzymatic Resolution of Amines” Chem. Commun. 1999, 127-128.

Takayama, S.; Chung, S.-J.; Igarashi, Y.; Ichikawa, Y.; Sepp, A.; Lechler, R.I.; Wu, J.Y.; Hayashi, T, Siuzdak, G.; Wong, C.-H.
“Selective Inhibition of b-1,4- and a-1,3-Galactosyltransferases: Donor Sugar-Nucleotide Based Approach” Bioorg. Med. Chem. 1999, 7, 401-409.

Takayama, S.; McDonald, J. C.; Ostuni, E.; Liang, M. N.; Kenis, J. P. A.; Ismagilov, R. F.; Whitesides, G. M.
“Patterning Cells and Their Environments Using Multiple Laminar Fluid Flows in Capillary Networks” Proc. Natl. Acad. Sci. USA 1999, 96, 5545-5548.

Kane, R. S.; Takayama, S.; Ostuni, E.; Ingber, D. E.; Whitesides, G. M.
“Patterning Proteins and Cells Using Soft Lithography
Biomaterials 1999, 20, 2363-2376.

1998

Takayama, S.; McGarvey, G. J.; Wong, C.-H.
“Enzymes in Organic Synthesis: Recent Developments in Aldol Reactions and Glycosylations” Chem. Soc. Rev., 1998, 26, 407-415.

Wittmann, T.; Takayama, S.; Weitz-Schmidt, G.; Wong, C.-H.
“Ligand Recognition by E- and P-Selectin: Chemoenzymatic Synthesis and Inhibitory Activity of Bivalent Sialyl Lewis X Derivatives and Sialyl Lewis X Carboxylic Acids” J. Org. Chem. 1998, 63, 5137-5143.

Wischnat, R.; Martin, R.; Takayama, S.; Wong, C.-H.
“Chemoenzymatic Synthesis of Iminocyclitol Derivatives: A Useful Library Strategy for the Development of Selective Fucosyltransfer Enzyme Inhibitors” Bioorg. Med. Chem. Lett. 1998, 8, 3353-3357.

Chung, S. J.; Takayama, S.; Wong, C.-H.
“Acceptor Substrate-Based Selective Inhibition of Galactosyltransferases” Bioorg. Med. Chem. Lett. 1998, 8, 3359-3364.

1997

Takayama, S.; Wong, C.-H.
“Chemoenzymatic Approach to Carbohydrate Recognition” Curr. Org. Chem. 1997, 1, 109-126.

Takayama, S.; McGarvey, G. J.; Wong, C.-H.
“MICROBIAL ALDOLASES AND TRANSKETOLASES: New Biocatalytic Approaches to Simple and Complex Sugars” Ann. Rev. Microbiol. 1997, 51, 285-310.

Wu, J., Takayama, S., Wong, C.-H., Siuzdak, G.
“Quantitative Mass Spectrometry for the Rapid Assay of Enzyme Inhibitors” Chem. & Biol., 1997, 4, 653-657.

Takayama, S.; Martin, R.; Wu, J.; Laslo, K.; Siuzdak, G.; Wong, C.-H.
“Chemoenzymatic Preparation of Novel Cyclic Imine Sugars and Rapid Biological Activity Evaluation Using Electrospray Mass Spectrometry and Kinetic Analysis” J. Am. Chem. Soc., 1997, 119, 8146-8151.

1996 and earlier

Takayama, S.; Shimazaki, M.; Qiao, L.; Wong, C.-H.
“Synthesis of Lactosamine Derivatives Using b-D-Galactosidase from Bacillus circulans” Bioorg. Med. Chem. Lett. 1996, 6, 1123-1126.

Jeong, J.-H.; Murray, B. W.; Takayama, S.; Wong, C.-H.
“Cyclic Guanidino-Sugars with Low pKa as Transition-State Analog Inhibitors of Glycosidases: Neutral Instead of Charged Species Are the Active Forms” J. Am. Chem. Soc. 1996, 118, 4227-4234.

Lin, C.-C.; Shimazaki, M.; Heck, M.-P.; Aoki, S.; Wang, R.; Kimura, T.; Ritzen, H.; Takayama, S.; Wu, S.-H.; Weitz-Schmidt, G.; Wong, C.-H.
“Synthesis of Sialyl Lewis X Mimetics and Related Structures Using Glycosyl Phoshite Methodology and Evaluation of E-Selectin Inhibition” J. Am. Chem. Soc. 1996, 118, 6826-6840.

Takayama, S.; Livingston, P. O.; Wong, C.-H.
“Synthesis of the Melanoma-associated Ganglioside 9-O-Acetyl GD3 Through Regioselective Enzymatic Acetylation of GD3 Using Subtilisin” Tetrahedron Lett., 1996, 37, 9271-9274.

Murray, B. W.; Takayama, S.; Schultz, J.; Wong, C.-H.
“Mechanism and Specificity of Human a-1,3-Fucosyltransferase V” Biochemistry, 1996, 34, 11183-11195.

Kimura, T.; Takayama, S.; Huang, H.; Wong, C.-H.
“A Novel and Practical Synthesis of N-Acetyl-D-lactosamine by the Tandem Use of Galactose Oxidase and b-D-Galactosidase” Angew. Chem. Int. Ed. Engl. 1996, 35, 2348-2350.

Mori, K.; Takayama, S.; Kido, M.
“Reduction of Bicyclo[3.3.1]nonane-2,8-diones with Baker’s Yeast”, Bioorg. Med. Chem. 1994, 2, 395-401.

Mori, K.; Takayama, S.; Yoshimura, S.
“Reduction of a Prochiral Diketone, 9-Methyl-trans-decalin-1,8-dione, with Baker’s Yeast”, Liebigs Ann. Chem. 1993, 91-95.