Nano-encapsulant of ascorbic acid-loaded apoferritin-assisted photoelectrochemical sensor for protease detection

A signal-on photoelectrochemical (PEC) biosensor based on nano-encapsulant of ascorbic acid-loaded apoferritin-assisted for protease detection is described. The loaded ascorbic acid could be released from the central cavity of apoferritin into the buffer solution as sacrificial electron donor to capture the photo-generated holes of CdTe quantum dots when light is turned on. In this system, the biosensor relied on monitoring the photocurrent intensity as a result of enzymatic substrate proteolysis in the homogeneous aqueous solution. A low detection limit of 2.7ngmL^-1 for trypsin in the linear range from 30 to 450ngmL^-1 is achieved. We believe that such a sensing system not only holds the potential ability as a probe for trypsin activity assay, but also could be used for the corresponding inhibitor-screening. It might provide a potentially feasible alternative tool for determining trypsin in human serum in a clinical laboratory. The established method could open a different perspective for PEC enzyme detection and provide a new platform for future development of PEC analysis with other clinically important proteins.