State Key Laboratory of Chemo/Biosensing and Chemometrics, College of Chemistry and Chemical Engineering, Hunan Provincial Key Laboratory of Biomacromolecular Chemical Biology, Hunan University, Changsha 410082, P. R. China.
Anal Chem. 2023 Aug 22;95(33):12435-12442. doi: 10.1021/acs.analchem.3c02095. Epub 2023 Aug 11.
The Poulos-Kraut heterolytic O-O cleavage mechanism is essential for natural peroxidases to activate HO. Current existing peroxidase-mimicking nanozymes, including photonanozymes (PNZs), however, are generally believed to prefer the Fenton-type mechanism of O-O homolysis, which produces OH radicals. Here, Ag ions are introduced into TiO PNZs to boost the hot hole-driven O-O heterolysis for the expedited HO activation in the peroxidase-like photonanozymatic reaction while inhibiting the Fenton-type O-O homolysis. The Ag-facilitated Poulos-Kraut heterolytic O-O cleavage mechanism for HO activation is explicated in terms of the speedy capture and exhaustion of photogenerated electrons by Ag and the dissociation of the peroxo-oxygen bridge in Ti-O-OH promoted by accumulated hot holes. Moreover, the enhanced photonanozymatic activity of TiO PNZs enables the construction of a rapid colorimetric sensing platform for Ag determination. This work provides valuable insights into the mechanism of HO activation and exemplifies a novel photoregulation strategy for controlling reaction pathways in nanozymes.
波劳斯-克劳特异裂 O-O 断裂机制对于天然过氧化物酶激活 HO 至关重要。然而，目前现有的过氧化物酶模拟纳米酶，包括光纳米酶 (PNZ)，通常被认为更倾向于 O-O 均裂的芬顿型机制，该机制会产生 OH 自由基。在这里，Ag 离子被引入 TiO2 PNZ 中，以促进热空穴驱动的 O-O 异裂，从而在过氧化物酶样的光纳米酶反应中加速 HO 的激活，同时抑制芬顿型的 O-O 均裂。Ag 促进的 HO 激活的 Poulos-Kraut 异裂 O-O 断裂机制可以根据 Ag 快速捕获和耗尽光生电子以及由积累的热空穴促进的 Ti-O-OH 中过氧氧桥的解离来解释。此外，TiO2 PNZ 的增强的光纳米酶活性使得可以构建用于 Ag 测定的快速比色传感平台。这项工作提供了对 HO 激活机制的有价值的见解，并展示了一种用于控制纳米酶中反应途径的新型光调控策略。
