Fabrication of a microfluidic chip containing dam, weirs and gradient generator for studying cellular response to chemical modulation

A microfluidic chip was designed and fabricated for studying cellular response to chemical modulation. The microfluidic network comprised an up-stream gradient-generating module and a down-stream cell culture module. The microchip was composed of a piece of glass plate and a covered PDMS film. By using a two-step wet etching method, the dam structure was fabricated on the inlet of the cell chamber facilitating cell positioning, and a series of weir structures were fabricated on the bottom of cell culture reservoirs facilitating cell seeding. This microfluidics exploited the advantage of lab-on-a-chip technology by integrating the generation of chemical concentration gradients and a series of cell operations including seeding, culture, stimulation and staining into a chip. Steady concentration gradients were generated by flowing two fluids in the network. Over time observation showed that the microchip was suitable for cell seeding and culture. The microchip described above was applied in studying the roles of As2O3 and buthionine sulfoximine (BSO) in mediating intracellular levels of reduced glutathione (GSH) and reactive oxygen species (ROS) in MCF-7 cells. MCF-7 cells showed dose dependent reaction to the chemical modulations. Upon the treatment with both As2O3 and BSO, GSH levels were down-regulated but ROS levels were up-regulated. As2O3 showed a stronger effect on ROS enhancement, while BSO was more effective on GSH depletion. The integrated microfluidic chip is able to perform multiparametric pharmacological profiling with easy operation, thus holds great potential for extrapolation to the cell based high-content drug screening.