Axial Chlorination Engineering of Single-Atom Nanozyme: Fe-N<sub>4</sub>Cl Catalytic Sites for Efficient Peroxidase-Mimicking
Shengjie Wei, Minmin Sun, Juan Huang, Zhengbo Chen, Xijun Wang, Lizeng Gao, Jijie Zhang
Abstract
Developing axial coordination engineering of single-atom nanozymes (SAzymes), directly regulating the axial coordination environment of the catalytic site, and optimizing the axial adsorption are meaningful and challenging for boosting the enzyme-like activities. Herein, the axial chlorination engineering of SAzyme with the Fe-N 4 Cl catalytic site (Fe-N 4 Cl/CNCl) was first proposed, exhibiting superior peroxidase-like activity compared to the traditional Fe-N 4 /CN SAzyme with Fe-N 4 site. The maximal reaction velocity (4.73 × 10 –5 M min –1 ), the catalytic constant (246.4 min –1 ), and the specific activity (81 U/mg) catalyzed by the Fe-N 4 Cl/CNCl SAzyme were 4.9 times, 3.9 times, and 2.7 times those of the Fe-N 4 /CN SAzyme, revealing the enormous advantages of axial chlorination engineering of SAzymes for remarkably improving enzyme-like activities. Moreover, the Fe-N 4 Cl/CNCl SAzyme also exhibited an enhanced inhibition effect of tumor cell growth in vitro and in vivo. The density functional theory calculation revealed that the Fe-N 4 Cl site was more favorable for releasing • OH radical, lowering the energy barrier of rate-determining step, and accelerating the reaction rate compared to the Fe-N 4 site. This work demonstrated the outstanding potential of axial chlorination engineering of SAzymes for improving enzyme-like activities and practical application in tumor therapy.