A perfusable microfluidic device with on-chip total internal reflection fluorescence microscopy (TIRFM) for in situ and real-time monitoring of live cells.

A microfluidic device integrated with a Total Internal Reflection (TIR)-based chip for cell observation and analysis was developed. This integrated device enables in situ Total Internal Reflection Fluorescence Microscopy (TIRFM) on adherent cells cultured under continuous medium perfusion. This TIR-based chip, allows TIRFM to be easily performed on cells without the assembly of complicated optical components and cell culture chambers. The integrated device was evaluated by tracking the movement of fluorescent beads and monitoring the location of insulin granules in mouse pancreatic ß-cells. This system offers higher signal-to-noise (S/N) ratio than epi-fluorescence microscopy (EPIFM), and comparable image quality to commercial TIRFM systems when imaging insulin granules. We also detected repetitive changes in intracellular Ca(2+) concentration in MIN6-m9 cells stimulated with KCl, which demonstrates quick perfusion for cell analysis while maintaining high S/N ratio.

Open-access and multi-directional electroosmotic flow chip for positioning heterotypic cells.

We propose a novel method of cell positioning using electroosmotic flow (EOF) to analyze cell-cell interactions. The EOF chip has an open-to-air configuration, is equipped with four electrodes to induce multi-directional EOF, and allows access of tools for liquid handling and of physical probes for cell measurements. Evaluation of the flow within this chip indicated that it controlled hydrodynamic transport of cells, in terms of both speed and direction. We also evaluated cell viability after EOF application and determined appropriate conditions for cell positioning. Two cells were successively positioned in pocket-like microstructures, one in each micropocket, by controlling the EOF direction. As an experimental demonstration, we observed contact interactions between two individual cells through gap junction channels. The EOF chip should provide ways to elucidate various cell-cell interactions between heterotypic cells.