Extending Single Entity Electrochemistry Towards the Detection of Single Bacteria in Micro Volumes
Single entity electrochemistry (SEE) is an emerging electroanalytical technique with the ability to push the limit of detection of electrochemical sensors to the single particle level. It measures the change in current over time, making SEE rapid, simple, and cost-effective. The type of current response observed in the scan can provide information about the physiochemical processes underlying the signal. While SEE was originally developed to detect single molecules and nanoparticles, it has been widely applied to micron-sized particles, including emulsion droplets, bacteria, viruses, and mammalian cells. Some recent advances in this technique have focused on the detection of microscopic quantities of cells, with the goal of detecting bacteria in agricultural samples. Picomolar levels of detection were recently achieved for single bacterial cells in bulk solution (Anal. Chem. 2018, 90, 20, 12123-12130). To further lower the level of detection, we have demonstrated that SEE can successfully detect Escherichia coli bacterial cells trapped in a micron-sized droplet at the surface of the electrode. The micro-sized droplet shows a lower level of detection similar to that of the bulk solution: at the femtomolar level. Interestingly, we have observed a two- to four-fold decrease in the current response time in the microenvironment vs the bulk.
single entity electrochemistry, bacteria, Escheria coli, adsorption, ultramicroelectrode
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VCU Graduate Research Posters