The contamination of freshwater sources by heavy metals has been an environmental concern for decades. Current methods to accurately quantify heavy-metal concentrations involve collecting the water sample and transporting it back to a laboratory for analysis. We report the development of a microfluidic device with the capability to detect environmentally relevant concentrations of lead in water samples. Microfluidic devices are advantageous as an on-site analytical instrument due to their portability, affordability, disposability, and the use of small sample volumes. When coupled with fluorescence detection, these platforms have the potential to provide sensitive detection of heavy-metal ions. In our device, we employ a naturally occurring, non-pathogenic freshwater bacterium, Caulobacter crescentus, which has unique physiological properties that make it a model organism for heavy-metal detection and bioremediation research. Bacterial growth studies completed with optical density and fluorescence measurements indicate that C. crescentus can tolerate lead ion concentrations of 10 �M Pb2+ and lower compared to wild-type growth. These results suggest that C. crescentus tolerates exposure to heavy-metal ions, and can be used predictably as a regenerative biological detector. Additionally, we utilize Leadmium Green AM fluorescent dye to detect intracellular concentrations of lead ions. Preliminary results indicate we can correlate intracellular lead concentrations of a live bacterial culture with concentration present in water samples. Finally, we integrate C. crescentus bacterial cells on a poly(dimethylsiloxane) microfluidic device for direct incubation, integration and detection of heavy-metal contaminated aqueous samples.

Microfluidic fluorescence detection of the intracellular heavy-metal uptake properties of <i>Caulobacter crescentus</i>

247th National Meeting (2014)

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Microfluidic fluorescence detection of the intracellular heavy-metal uptake properties of Caulobacter crescentus