Controlled Synthesis And Catalytic Activity Of Iron Containing Nanozymes And Their Application In Biochemical Reactions

Nanozymes,as nanomaterials with enzyme-like catalytic activity,have attracted much attention from researchers in recent years.Compared to traditional natural enzymes,nanozymes offer the advantages of higher stability,lower cost and easier storage.With the development of nanoscience and technology and a better understanding of its properties,nanozymes are expected to directly replace conventional enzymes by mimicking and designing the active centres of natural enzymes.Therefore,in the field of biomedicine,nanozymes have a wide range of promising applications in antibacterial therapy and tumor treatment.Among the nanozymes that have emerged,iron-containing nanozymes have shown particularly outstanding catalytic activity and stability.Despite the existence of various ironcontaining nanozyme,the use of their properties to improve the specificity of biotherapeutics and sensitivity in bioassays remains a major focus and bottleneck of current research.In this paper,by developing iron-containing nanozymes and investigating their peroxidase catalytic properties and catalytic mechanism,and by combining the physicochemical properties and catalytic activity of the nanozymes,they have been successfully applied to tumor therapy and bio-small molecule detection,initially realising the multifunctional application of the nanozymes.The main research is as follows:(1)A one-step co-precipitation method was used to synthesise ultra-small FeOx nanozymes at a lower temperature using Cu2+ as a sacrificial agent.their catalytic activity of mimicking peroxidase was optimized at a temperature of 40℃ and pH=4,and they could also perform well as mimicking catalase in a neutral environment.the combination of multiple catalytic activities of FeOx nanozymes makes them an effective treatment for cancer promising nanomedicine.The experimental results show that FeOx nanozymes,upon entering tumor cells,first accumulate in lysosomes,which are capable of producing ·OH in the acidic microenvironment of lysosomes.at the same time,our prepared nanozymes also have the ability to deplete GSH,which is much higher than normal cells due to the abnormal expression of GSH in the tumor microenvironment,therefore,our prepared FeOx nanozymes can reverse the abnormal GSH level by GSH depletion.reversing the abnormal level of GSH and thus alleviating drug resistance.In addition,the nanozyme we fabricated was able to catalyse the breakdown of H2O2 to O2,thereby alleviating the hypoxic environment of the tumor to some extent and improving the function of the immune system in treating the tumor.Meanwhile,after testing on normal cells,it was found that the cytotoxicity of our synthesised FeOx nanozyme was very low and had almost no effect on normal cells.More importantly,the FeOx nanozyme showed excellent stability and its enzymatic activity could be maintained for at least 6 months.The high stability and versatile catalytic activity make FeOx nanozymes a promising nanomedicine for tumor treatment applications.(2)MOF-derived bimetallic two-dimensional nanosheet FeCo-MOF materials have been synthesised at room temperature using a simple sonication method.Compared to their monometallic counterparts(Fe-MOF,Co-MOF),the bimetallic FeCo-MOF nanosheets have similar morphology and conformation,but the synthesis of bimetallic MOF brings a higher peroxidase-like catalytic activity to the materials.Kinetic experiments have shown that our synthesised 2D FeCo-MOF nanosheets have a high affinity for TMB with Km values as low as 0.3767 mM.Mechanistic studies have shown that the peroxidase-like activity of 2D FeCo-MOF is mainly derived from the ·OH radical.Due to its high peroxidase-like activity,the 2D FeCoMOF nanozyme was used to construct a nanoplatform to identify multiple targets,namely H2O2 and glutathione.The work in this chapter not only provides a highly active bimetallic MOF material for the design of a highly sensitive assay for GSH-related clinical diagnostics,but the systematic study on bimetallic MOF will also provide referenceable design ideas for the development of more efficient nanozymes.