Flow cytometry of Escherichia coli on nucrifluidic devices

Flow cytometry of the bacterium Escherichia coli was demonstrated on a micr ofabricated fluidic device (microchip). The channels were coated with poly( dimethylacrylamide) to prevent cell adhesion, and the cells were transporte d electrophoretically by applying potentials to the fluid reservoirs. The c ells were electrophoretically focused at the channel cross and detected by coincident light scattering and fluorescence. The E. coli were labeled with a membrane-permeable nucleic acid stain (Syto15), a membrane-impermeable n ucleic acid stain (propidium iodide), or a fluorescein-labeled antibody and counted at rates from 30 to 85 Hz. The observed labeling efficiencies for the dyes and antibody were greater than 94%.