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894 results on '"Liu, Songqin"'

32. Regulating Reactive Oxygen Intermediates of Fe−N−C SAzyme via Second‐Shell Coordination for Selective Aerobic Oxidation Reactions.

Author

Xu, Yuan, Ma, Yuanjie, Chen, Xinghua, Wu, Kaiqing, Wang, Kaiyuan, Shen, Yanfei, Liu, Songqin, Gao, Xuejiao J., and Zhang, Yuanjian

Subjects
REACTIVE oxygen species, ELECTRON density, CYTOCHROME P-450, FERMI level, CHARGE exchange
Abstract

Reactive oxygen species (ROS) regulation for single‐atom nanozymes (SAzymes), e.g. Fe−N−C, is a key scientific issue that determines the activity, selectivity, and stability of aerobic reaction. However, the poor understanding of ROS formation mechanism on SAzymes greatly hampers their wider deployment. Herein, inspired by cytochromes P450 affording bound ROS intermediates in O2 activation, we report Fe−N−C containing the same FeN4 but with tunable second‐shell coordination can effectively regulate ROS production pathways. Remarkably, compared to the control Fe−N−C sample, the second‐shell sulfur functionalized Fe−N−C delivered a 2.4‐fold increase of oxidase‐like activity via the bound Fe=O intermediate. Conversely, free ROS (⋅O2−) release was significantly reduced after functionalization, down to only 17 % of that observed for Fe−N−C. The detailed characterizations and theoretical calculations revealed that the second‐shell sulfur functionalization significantly altered the electronic structure of FeN4 sites, leading to an increase of electron density at Fermi level. It enhanced the electron transfer from active sites to the key intermediate *OOH, thereby ultimately determining the type of ROS in aerobic oxidation process. The proposed Fe−N−Cs with different second‐shell anion were further applied to three aerobic oxidation reactions with enhanced activity, selectivity, and stability. [ABSTRACT FROM AUTHOR]

Published
2024
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43. Metal-ligand dual-site single-atom nanozyme mimicking urate oxidase with high substrates specificity.

Author

Wang, Kaiyuan, Hong, Qing, Zhu, Caixia, Xu, Yuan, Li, Wang, Wang, Ying, Chen, Wenhao, Gu, Xiang, Chen, Xinghua, Fang, Yanfeng, Shen, Yanfei, Liu, Songqin, and Zhang, Yuanjian

Subjects
BIOCHEMICAL substrates, SYNTHETIC enzymes, X-ray photoelectron spectroscopy, SOFT X rays, RADIOLABELING, OXIDASES, DUAL-energy X-ray absorptiometry
Abstract

In nature, coenzyme-independent oxidases have evolved in selective catalysis using isolated substrate-binding pockets. Single-atom nanozymes (SAzymes), an emerging type of non-protein artificial enzymes, are promising to simulate enzyme active centers, but owing to the lack of recognition sites, realizing substrate specificity is a formidable task. Here we report a metal-ligand dual-site SAzyme (Ni-DAB) that exhibited selectivity in uric acid (UA) oxidation. Ni-DAB mimics the dual-site catalytic mechanism of urate oxidase, in which the Ni metal center and the C atom in the ligand serve as the specific UA and O2 binding sites, respectively, characterized by synchrotron soft X-ray absorption spectroscopy, in situ near ambient pressure X-ray photoelectron spectroscopy, and isotope labeling. The theoretical calculations reveal the high catalytic specificity is derived from not only the delicate interaction between UA and the Ni center but also the complementary oxygen reduction at the beta C site in the ligand. As a potential application, a Ni-DAB-based biofuel cell using human urine is constructed. This work unlocks an approach of enzyme-like isolated dual sites in boosting the selectivity of non-protein artificial enzymes. Single-atom nanozymes are a type of non-protein artificial enzymes and promising for mimicking enzyme active centers, but lack recognition sites to confer substrate specificity. Here, the authors report on a metal-ligand dual-site single-atom nanozyme (Ni-DAB) that mimics the dual-site catalytic mechanism of urate oxidase and has high selectivity in uric acid (UA) oxidation. [ABSTRACT FROM AUTHOR]

Published
2024
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