Photoelectrochemical and quartz crystal microbalance dual-mode assay of protein tyrosine phosphatase 1B activity based on hollow CuO and TiO2 polyhedra

Protein tyrosine phosphatase 1B (PTP1B) serves vital functions in insulin/leptin mediated signaling, and its abnormal expression may contribute to type II diabetes and obesity. In this work, a photoelectrochemical (PEC)- quartz crystal microbalance (QCM) dual-mode sensing platform was constructed for PTP1B activity assay based on hollow CuO and TiO2 polyhedra. After the immobilization of PTP1B-specific phosphopeptide (P-peptide) onto the hollow CuO polyhedra-decorated indium-tin oxide (ITO) electrode, the hollow TiO2 polyhedra were introduced to the sensing platform by the specific interaction between TiO2 and phosphate groups of P-peptide. Because of the matched energy levels of CuO and TiO2, a large cathodic photocurrent was produced under visible light irradiation. When PTP1B was present, PTP1B could specifically recognize and dephosphorylate the Ppeptide. This led to the removal of TiO2 polyhedra from the electrode, resulting in a decrease of photocurrent. On the other hand, the detached hollow TiO2 polyhedra were further quantitatively detected by a QCM electrode. Thus, the PTP1B activity was highly sensitively and selectively assayed by the constructed PEC-QCM dual-mode biosensor. Moreover, this dual-mode biosensor showed great potential in protein phosphatase activity analysis and the protein phosphatase-targeted drug discovery.