Chemical Sensing via Chemotaxis of Euglena gracilis Confined in an Isolated Micro-Aquarium
On-chip cytotoxicity sensing for liquid substances was investigated by using the microbial chemotaxis of Euglena gracilis. The Euglena cells were confined in a closed-type micro-aquarium in a PDMS microchip, and the micro-aquarium was isolated from two microchannels to flow test and reference liquid substances. Small molecules of liquids permeated into PDMS and diffused into the water in the micro-aquarium, and thus, the chemical concentration gradient of test liquids was built in the micro-aquarium. The negative chemotactic movements of Euglena cells were observed for ethanol down to 0.5% within 2-5 min after the injection of diluted ethanol into one of the separated microchannels (counter reference = pure water). On the other hand, when 0.5% H2O2 was introduced as a test liquid (counter reference = pure water), the Euglena cells fell into continuous rotation instead of single step turning and/or straight forward swimming. As a result, total swimming activity in the micro-aquarium decreased even after H2O2 flow was switched back to water. The observation shows that the types of cytotoxic effects can be identified through the cell movement analysis.
Evangelos Hristoforou and Dr. Dimitros S. Vlachos
K. Ozasa et al., "Chemical Sensing via Chemotaxis of Euglena gracilis Confined in an Isolated Micro-Aquarium", Key Engineering Materials, Vol. 605, pp. 95-98, 2014