Ultrasensitive alkaline phosphatase activity assay based on controllable signal probe production coupled with the cathodic photoelectrochemical analysis

A highly sensitive and selective split-type perovskite-based photoelectrochemical (PEC) platform was developed for measuring alkaline phosphatase (ALP) activity in milk and serum samples. ALP in the test sample hydrolyzed 2-phosphate sesquimagnesium salt hydrate (AAPS) in a 96-microwell plate to produce ascorbic acid (AA), a PEC electron donor. The resulting AA, which could preferentially annihilate the photogenerated holes, indirectly reflects ALP activity. The PEC used a cetyltrimethylammonium bromide (CTAB)-functionalized CH3NH3PbI3 (CTAB@CH3NH3PbI3) film as the cathode to monitor the controlled AA production. Due to the excellent pho-toelectric characteristics of the CH3NH3PbI3 perovskite and the split-type assay, excellent sensitivity and selec-tivity for ALP detection were obtained. Under the optimum experimental conditions, ALP activity with a limit of detection (LOD) of 2.6 x 10(-4) U/L in a linear dynamic range of 10(-3) similar to 102 U/L was obtained. With its sensitive, rapid, and high-throughput detection capabilities, this split-type and label-free PEC platform has great potential for use in food and biomedical analysis.

Automated summary

A highly sensitive and selective split-type perovskite-based photoelectrochemical (PEC) platform was developed to measure alkaline phosphatase (ALP) activity in milk and serum samples. The PEC used a CTAB@CH3NH3PbI3 film as the cathode to monitor the controlled AA production. With excellent sensitivity and selectivity, the platform has great potential for use in food and biomedical analysis.