Ultrasensitive Paper-Based Photoelectrochemical Biosensor for Acetamiprid Detection Enabled by Spin-State Manipulation and Polarity-Switching
Yuanyuan Chen, Jiaxin Liang, Jiahui Xu, Li Shan, Jingjing Lv, Chengjun Wu, Lina Zhang, Li Li, Jinghua Yu
Abstract
Efficient carrier separation is vitally crucial to improving the detection sensitivity of photoelectrochemical (PEC) biosensors. Here, we developed a facile strategy to efficiently regulate the carrier separation efficiency of the photoactive matrix BiOI and In 2 S 3 signal label functionalized paper chip by manipulation of electrons spin-state and rational design of electron transport pathways. The spin-dependent electronic structures of BiOI and In 2 S 3 were regulated via enhanced electron-spin parallel alignment induced by an external magnetic field, markedly retarding carrier recombination and extending their lifetime. Simultaneously, with the progress of the target-induced catalytic hairpin assembly process, the transfer path of photogenerated carriers was changed, leading to a switch in photocurrent polarity from cathode to anode. This reversed electron transport pathway not only boosted the separation ability of photogenerated electrons but also eliminated false-positive and false-negative signals, thereby further improving the detection sensitivity. As a proof of concept, the well-designed magnetic field-stimulated paper-based PEC biosensor showed highly selectivity and sensitivity for acetamiprid assay with a wide linear range of 1 fM to 20 nM and an ultralow detection limit of 0.73 fM. This work develops a universal strategy for improving the sensitivity of biosensors and exhibits enormous potential in the fields of bioanalysis and clinical diagnosis.