Synthesis Of Novel Composite Nanoenzymes And Its Evolution In Different Physiological Environments

Nanozymes are highly efficient nanomaterials with similar natural enzyme activities,which are widely used in molecular detection,biomedical therapy and other fields with high stability,low preparation cost and adjustable performance.The body is metabolized to produce oxygen-containing chemicals,called reactive oxygen species（ROS）,and when the body produces excess ROS,it damages normal cellular structures,causing the body to produce an inflammatory response and eventually lead to various diseases.Nano-cerium oxide（CeO₂ NPs）can mimic the catalytic activity of a variety of enzymes and can effectively remove ROS to treat inflammation-related diseases,and is a nanozyme that has received widespread attention in recent years.At present,the synthesis methods of CeO₂ NPs involve reaction conditions such as high temperature or high pressure,which is not in line with the theme of green science.In this project,a method for the rapid and efficient synthesis of CeO₂ NPs under normal temperature and pressure conditions was independently developed.Composites often exhibit superior properties to one-component materials,so in this project,mesoporous silica was used to encapsulate CeO₂ NPs to obtain a novel composite nanoenzyme CeO₂@m Si O₂,which is economical,green and efficient.CeO₂ NPs have high efficiency and diversified enzyme catalytic activity,have broad application prospects in the biomedical field,and have shown good therapeutic effects in many animal disease models.Despite their excellent properties,CeO₂ NPs have limited clinical use,in part due to a lack of biosafety assessment.The internal environment of the human body is complex and diverse,different physiological environments have different molecules,ions,proteins and p H values,etc.,when CeO₂ NPs enter different physiological environments,aggregation or degradation may occur,resulting in their loss of original catalytic activity.CeO₂NPs have great biomedical potential,and according to the route of human administration,five different physiological environments of oral fluid,gastric juice,intestinal juice,lung fluid and cell culture fluid were simulated in this project,and the evolution of self-developed CeO₂ NPs and CeO₂@m Si O₂ in different physiological environments of the human body was explored.The experimental content mainly involves the study of the stability of nanoenzymes in physiological environment,the study of enzyme catalytic activity and the study of antioxidant capacity.Experiments have shown that the stability of CeO₂@m Si O₂ in various physiological environments is better than that of CeO₂ NPs.In the physiological environment,CeO₂ NPs and CeO₂@m Si O₂ can maintain certain enzyme catalytic activity in a short period of time,and the enzyme catalytic activity of CeO₂@m Si O₂ in a long time is better than that of CeO₂ NPs.The cell antioxidant test showed that the ROS content in the blank group was 0.44%,and the ROS content in the cells treated with H₂O₂was 39.6%.CeO₂ NPs and CeO₂@m Si O₂ reduced the ROS content of H₂O₂-treated cells to 18.7%and 8.35%,respectively,indicating that CeO₂@m Si O₂ had better antioxidant capacity than CeO₂ NPs.After being retained in the physiological environment for a period of time,both of the two nanomases can remove intracellular ROS with certain antioxidant capacity.The antioxidant capacity of CeO₂@m Si O₂is stronger than that of CeO₂ NPs,especially in the lung fluid environment,CeO₂ NPs only reduces ROS by 5.7%.CeO₂@m Si O₂ reduced ROS by 30.38%,so CeO₂@m Si O₂ had better antioxidant activity in the pulmonary fluid environment.The experimental results of the evolution of nanomases in physiological environment show that CeO₂@m Si O₂ has better stability and longer-lasting enzyme catalytic activity and antioxidant capacity in physiological environment.