Redox cycling-based electrochemical reporter gene assay for single cells using a scanning electrochemical microscope-microwell system

Single-cell analyses are important for providing new insights into cellular biology. Here we report an electrochemical reporter gene assay for single cells using a scanning electrochemical microscope (SECM)-microwell system. Each microwell trapped a single cell that synthesized a reporter protein, secreted alkaline phosphatase (SEAP). The SEAP catalyzed the hydrolysis of p-aminophenyl phosphate to p-aminophenol (PAP). A disk electrode in the SECM was positioned above the microwell and monitored the oxidation currents of PAP derived from SEAP. In addition, ring electrodes were prepared on the microwell device to induce redox cycling between the ring and disk electrodes, thus amplifying the electrochemical signals from the reporter protein. The redox cycling-based electrochemical reporter gene assay is useful for single-cell analyses.