Development of Electrochemical Biolithograpy and application to Cellular Chips

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Microfluidic systems have been widely investigated for biological applications and hold great promise in the development of diagnostic assays and bioreactors. The combination of the surface patterning techniques with the microfluidic systems paves the way to multi-functional, high-throughput, and cost-effective analysis, in which the "real-time" and "on-demand" micropatterning of bioelements within the microchannels would be essentially required since such delicate materials are unstable to desiccation, oxidation, and heat. However, most of the photolithography-based techniques are unable to be applied within the sealed microchannels.In this research, we have developed a novel technique "electrochemical bio-lithography", which enables the localized immobilization of proteins and cells within 3D microstructures such as microfluidic channels. The principle of the technique is based on our finding that the albumin- or heparin-coated surfaces, initially anti biofouling, rapidly becomes protein- and cell-adhesive upon exposure to the reactive oxidizing agent such as hypobromous acid, which can be produced by the electrochemical oxidation of bromide ion in a biological buffer solution. Since this lithography can be conducted under typical physiological conditions, it enables the spatiotemporal control of cell adhesion and growth on substrates; it facilities the stepwise immobilization of multitype protein arrays and multiphenotype cell arrays. And importantly, this technique is simple enough to be integrated into the miniaturized and semi-closed systems such as microfluidic devices, indicating the possible "on-demand" immobilization of proteins and living cells just prior to use of the microfluidic biodevices. In addition, we have achieved rapid cellular arrangement in the semi-closed microfluidic channel by combining electrochemical bio-lithography with negative dielectrophoresis (DEP).