Fabrication of a bio-MEMS based cell-chip for toxicity monitoring

A bio-MEMS based cell-chip that can detect a specific toxicity was fabricated by patterning and immobilizing bioluminescent bacteria in a microfluidic chip. Since the emitted light intensity of bioluminescent bacteria changed in response to the presence of chemicals, the bacteria were used as the toxicity indicator in this study. A pattern of immobilized cells was successfully generated by photolithography, utilizing a water-soluble and negatively photosensitive polymer, PVA-SbQ (polyvinyl alcohol-styrylpyridinium) as an immobilization material. Using the recombinant Escherichia coli (E. coli) strain, GC2, which is sensitive to general toxicity, the following were investigated for the immobilization: an acceptable dose of long-wavelength UV light, the biocompatibility of the polymer, and the effect of the chip-environment. We found that 10 min of UV light exposure, the toxicity of polymer (SPP-H-13-bio), and the other chip-environment did not inhibit cell metabolism significantly for making a micro-cell-chip. Detection of a specific toxicity was demonstrated by simply immobilizing the bioluminescent bacteria, DK1, which increased bioluminescence in the presence of oxidative damage in the cells. An injection of hydrogen peroxide of 0.88 mM induced 10-fold increase in bioluminescent intensity confirming the capability of the chip for toxicity monitoring.