Design,Activity Regulation And Biological Application Of Bimetallic Alloy Nanozymes

Nanozymes are a class of nanomaterials that can mimic the catalytic activity characteristics of natural enzymes.Compared with natural enzymes,nanozymes have many advantages,such as good stability,easy preparation,low price and wide range of application,attracting the attention of researchers in chemistry,materials science,biology and medicine,and are expected to become a new generation of analog enzymes.However,nanozymes suffer from low catalytic activity,unclear understanding of the catalytic mechanism,and limited depth and breadth of applied research,making them not yet able to exert their greatest advantages as an ideal substitute for natural enzymes.Therefore,designing nanomaterials with high enzyme-like catalytic activity,studying the mechanism of their catalytic activity and exploring their wider application range are of great significance for the rapid realization of the application and development of nanozymes.This dissertation will focus on the above-mentioned main issues,takingCu based bimetallic alloy nanozymes as model,based on the rational design idea of electronic structure regulation and synergistic catalysis of metal catalysts,systematically studies the enzyme-like and RONS scavenging catalytic activity regulation of metal nanozyme and structure-activity relationship,explore their potential applications in bioprotection and therapy.The main contents are as follows:1.PtCu nanoenzymes with composition-dependent ROS scavenging activity to prevent pathologicalα-syn transmission in Parkinson’s disease.In order to explore the effect of composition on the enzyme-like catalytic activity,PtCu nanoalloys（NAs）with tunable proportions and uniform morphology were prepared by hydrothermal method.The results show that PtCu NAs have the catalytic activity of multiple redox enzymes such as catalase（CAT）,peroxidase（POD）and superoxide dismutase（SOD）,showing excellent antioxidant capability.The catalytic activity of the nanozyme can be regulated by changing the composition ratio of PtCu NAs.Based on its excellent antioxidant capacity,PtCu NAs were applied to alleviate Parkinson’s disease（PD）due to the over production of reactive oxygen species induced byα-synuclein prefabricated fibrils（α-Syn PFF）.Through the primary cortical neuronal cell experiments,the results showed that PtCu NAs significantly reduced the neuronal ROS level induced byα-Syn PFF,pathological and neurotoxicity ofα-Syn,and blocked the pathologicalα-Syn transmission from cell to cell.This provides a new strategy for the application of nanozymes in the treatment of PD diseases,and provides reference for the treatment and prevention of other neurodegenerative diseases.2.Composition regulating enzyme-like activity of small size IrCu alloy nanozyme for high catalytic efficiency.Nanoparticles of small size have larger specific surface area,which will expose more active sites and have stronger BBB penetration.IrCu alloy nanozymes with small size and adjustable composition were prepared by hydrothermal method.A variety of characterization techniques proved the formation of IrCu alloy nanozymes with particle size less than 8 nm and uniform element distribution.The results demonstrated that IrCu alloy nanozymes showed composition dependent enzyme-like catalytic activities,including peroxidase,catalase and superoxide dismutase,as well as the reactive oxygen nitrogen species scavenging ability（·OH,DPPH·and ONOO^-）,showing excellent antioxidant effect.The composition of IrCu alloy nanozymes play the significant role in regulating the multiple-enzyme like and free radicals scavenging activities.The efficient enzyme-like catalytic activity and excellent antioxidant capacity of IrCu alloy nanozymes will provide ideal nanomedicine candidates for the prevention and treatment of ROS and RNS related diseases.3.Component-dependent enzyme-like catalytic activity and structure-activity relationship ofCu based bimetallic nanozyme.In order to comparatively study the effect of component type on the enzyme-like catalytic activity,five kinds ofCu-based metallic nanoalloys with similar size,M₃Cu（M=Pt、Pd、Rh、Ru、Ir）,were designed and prepared by hydrothermal method.Through enzyme-like catalytic experiments,it was found that each of the five alloy nanozymes exhibit multiple enzyme-like activity such as peroxidase,oxidase,catalase and superoxide dismutase,as well as the free radicals scavenging ability to reduce·OH,DPPH·and c-PTIO·.The alloy nanozymes showed component type dependent enzyme-like catalytic activity in distinct activity order.Through the theoretical analysis of the d-band center,it is found that the more negative the position of the surface d-band center is,the more favorable it is for the adsorption and cleavage of H₂O₂to generate adsorbed OH*,which in turn promotes the catalytic activity of peroxidase-like enzymes.This study not only provide a deeper understanding of the regulation mechanism of enzyme-like catalytic activity via component synergistic catalysis,but also provides theoretical basis and guidance for the rational design of nanozymes with high catalytic activity and their application in biology.In summary,we have studied the regulation and structure-activity relationship of the catalytic activity of bimetallic alloy nanozymes by changing the component ratio and component type,and realized new applications in biology.This will provide new insights into the regulation of the catalytic activity of nanozymes and provide more possibilities for new biological applications in the future.