A Nanoenzyme-Sensitized Photoelectrochemical Biosensing Platform Integrated with a Two-Step Radical Polymerization Signal Amplification Strategy for Ultrasensitive Detection of PTP1B Activity
Huan Wang, Yiyuan Yang, Cuicui Du, Hejie Zheng, Xiaohua Zhang, Jinhua Chen
Abstract
Dephosphorylation is an essential process in cellular signaling with protein phosphatases playing a critical role in cellular functions and disease mechanisms. Herein, a novel and ultrasensitive photoelectrochemical (PEC) biosensing platform for detecting protein tyrosine phosphatase 1B (PTP1B) activity was developed, based on the sensitization effect of a magnetic ZnFe 2 O 4 @ZrMOF nanoenzyme integrated with a two-step radical polymerization signal amplification strategy. The PTP1B-specific phosphorylated peptide (p-peptide) was immobilized on a 96-well plate and then coupled to the ZnFe 2 O 4 @ZrMOF nanoenzyme through coordination between its phosphate groups and Zr 4+ ions. When PTP1B was present, the p-peptide was specifically recognized and dephosphorylated, causing the release of ZnFe 2 O 4 @ZrMOF. After magnetic separation, the detached ZnFe 2 O 4 @ZrMOF nanoenzyme, with peroxidase (POD)-like and photoresponsive oxidase (OXD)-like activities, was used as a signal probe, which not only exhibited a PEC signal sensitization effect on the AgInS 2 /Ag 2 S/magnetic ITO (MITO) photoelectrode but also triggered two-step radical polymerization reactions to form the ZnFe 2 O 4 @ZrMOF/polydopamine (PDA)/ poly(ferrocenylmethyl methacrylate) (PFcMMA) composite for further enhancing the PEC signal amplification. The proposed PEC biosensing platform achieved ultrasensitive detection of PTP1B activity, demonstrating a wide linear range (10 aM–0.1 μM) and an ultralow detection limit (3.92 aM), along with good reproducibility, satisfactory stability, high selectivity, and promising practical applicability. This work provides a prospective method for protein phosphatase activity assay, facilitating early disease diagnosis and therapeutic development alongside an innovative signal amplification strategy for advancing PEC biosensor sensitivity.