Toxicity sensing by using chemotactic reaction of microbial cells confined in microfluidic chip

Abstract

We developed and examined a toxicity sensing microchip, where 200-300 cells of flagellated microbes (Euglena gracilis) were placed and their movements were monitored with a video camera. The microchip had two microchannels for test sample and reference flow, and the cells were confined completely in a separated closed-space (micro-aquarium). The two microchannels run aside of the micro-aquarium, and molecules of test sample permeated into the micro-aquarium from the microchannels via diffusion through porous polydimethylsiloxane (PDMS) wall. The toxicity of test sample was evaluated real-time from the spatial distribution of the cells and swimming motion. Highly quantitative toxicity monitoring was achieved, owing to the complete confinement of microbial cells and sensitive chemotaxis of the cells.