Carbon-Ag/AgCl Probes for Detection of Cell Activity in Droplets

In this study, we fabricated a probe consisting of a carbon nanoelectrode and an Ag/AgCl reference electrode for detecting the activity of cells in single droplets. HeLa cells were confined into a single droplet, and the alkaline phosphatase (ALP) activity of the cells was electrochemically measured using the probe inserted into the droplet. The ALP of the confined cells catalyzed the hydrolysis of p-aminophenyl phosphate (PAPP) to yield p-aminophenol (PAP) that gave electrochemical responses. Since the tip of the carbon-Ag/AgCl probe is very small, it is useful for electrochemical analysis of cells using droplets.