Polarity Conversion of the Ag 2 S/AgInS 2 Heterojunction by Radical-Induced Positive Feedback Polydopamine Adhesion for Signal-Switchable Photoelectrochemical Biosensing

作者：Zijun Li, Jiarui Lu, Fan Wu, Min Tao, Wanting Wei, Zizheng Wang, Zizheng Wang, Zhaoyin Wang, Zhaoyin Wang, Zhihui Dai · 发表于：Analytical Chemistry · 年份：2023 · DOI：10.1021/acs.analchem.3c02758 · 被引用次数：56 · 研究领域：Quantum Dots Synthesis And Properties、Advanced Photocatalysis Techniques、Conducting polymers and applications

Efficient tuning of the polarity of photoactive nanomaterials is of great importance in improving the performance of photoelectrochemical (PEC) sensing platforms. Herein, polarity of the Ag 2 S/AgInS 2 heterojunction is converted by radical-induced positive feedback polydopamine (PDA) adhesion, which is further employed to develop a signal-switchable PEC biosensor. In the nanocomposites, Ag 2 S and AgInS 2 achieve electron–hole separation, exhibiting a strong anodic PEC response. Under the irradiation of light, the Ag 2 S/AgInS 2 heterojunction is able to produce superoxide radical and hydroxyl radical intermediate species, leading to the polymerization of dopamine (DA) and the subsequent adhesion of PDA onto the Ag 2 S/AgInS 2 heterojunction (Ag 2 S/AgInS 2 @PDA). By constructing a new electron-transfer pathway with PDA, the polarity of the Ag 2 S/AgInS 2 heterojunction is converted, and the PEC response changes from anodic to cathodic photocurrents. In addition, since the photoreduction activity of PDA is stronger than that of the Ag 2 S/AgInS 2 heterojunction, more superoxide radical can be produced by Ag 2 S/AgInS 2 @PDA once PDA is generated, thereby promoting the generation of PDA. Consequently, a positive feedback mechanism is established to enhance the polarity conversion of the Ag 2 S/AgInS 2 heterojunction and amplify the responding to DA. As a result, the bioanalytical method is capable of sensitively quantifying DA in 10 orders of magnitude with an ultralow limit ...