Use of a gradient-generating microfluidic device to rapidly determine a suitable glucose concentration for cell viability test

We successfully determined a suitable glucose concentration for endothelial cells (ECs) using a gradient-generating microfluidic chip and a micro-stamper that were fabricated using micro-electro-mechanical systems (MEMS) technology. Our strategy was to generate a stable concentration gradient in the observation area based on a microfluidic network and micro-mixers, which produced a concentration gradient under various flow rates. The areas for cell adhesion were delineated on a glass slide with a micro-stamper using the micro-contact printing (μCP) method. We also discuss which glucose concentration gradients are suitable for cell viability test (i.e., 0-0.2%, 0.05-0.15%, and 0.06-0.17%). After examining various concentration gradients, the suitable glucose concentration for EC's viability test was determined to range from 0.077% (4.2 mM) to 0.147% (8.16 mM). Higher or lower concentrations caused the ECs to atrophy or die. In this study, we describe a gradient-generating microfluidic chip that can be used to produce various drug concentrations for multi-concentration tests.