Applications Of Non-noble Metal Doped Carbon-based Nanozymes In Environmental And Biological Analysis

Nanozymes are a kind of nanomaterials with enzyme-like activity.Compared with traditional natural enzymes,nanozymes have received more and more attention from researchers because of their stable properties,easy storage,and large-scale production.Carbon-base nanomaterials,as a class of nanomaterials,have been widely studied because of their well-defined electronic and geometric structures,which can be easily designed to mimic the catalytic activity centers of natural enzymes.So far,various carbon-based nanomaterials have been reported to mimic the catalytic activities of catalase,oxidase,peroxidase and superoxide dismutase.Carbon-based nanozymes have been widely used in biosensors,environmental governance,disease treatment and other fields due to their excellent enzyme-imitating activity.The desirable carbon-based nanomaterials with enzyme-imitating activity and functionalization can be obtained by doping the atoms or ions of some elements into the main structure of carbon nanomaterials.In this paper,we developed two colorimetric assays for the detection of biological enzymes and metal ions using non-noble metal doped carbon-based nanozymes,and applied them to environmental and biological analysis.In chapter 1,we mainly introduced the development process,classification,and application of nanozymes,and finally we summarized the research content and significance of this paper.In chapter 2,we prepared a colorimetric detection method for alkaline phosphatase by Fe/NC nanozymes with peroxidase-like activity through pyrolysis.Fe/NC nanozymes were obtained by high temperature calcination of ZIF-8 coated iron phthalocyanine(?)under the protection of nitrogen,which can maintain stability in extreme environments and long-term storage.Fe/NC nanozymes can catalyze the oxidation of TMB by hydrogen peroxide to obtain the corresponding blue product(Ox TMB),which has obvious UV absorption at 652nm.Alkaline phosphatase can hydrolyze ascorbate-2-phosphate to produce reductive ascorbic acid,which can reduce Ox TMB to make the system blue off.There is a good linear relationship between the change of absorbance in the system and the activity of alkaline phosphatase in the range of 0.1-1.5 U L^-1.The colorimetric method we have established can realize the sensitive detection of alkaline phosphatase,and the limit of detection is 0.05 U L^-1.We applied this detection system to the detection of alkaline phosphatase activity in human serum samples and obtained satisfactory results.In chapter 3,we synthesized a two-dimensional nanosheet structure of Cu/NC nanozymes by using the salt template method,which has excellent peroxidase-like activity.Therefore,we designed a mercury ion colorimetric detection method based on Cu/NC nanozymes.Cu/NC nanozymes can catalyze hydrogen peroxide to generate hydroxyl radicals,which can oxidize TMB to blue oxidized TMB(Ox TMB).Glutathione is reductive and can reduce Ox TMB to colorless,making the blue color of the system fade and the absorbance decrease.Mercury ions can combine with the sulfhydryl group of glutathione to make it lose its reducibility and restore the absorbance of the system.The absorbance recovery of the system is related to the concentration of added mercury ions.Therefore,a mercury ion detection based on Cu/NC nanozymes could be established.The linear range of mercury ions was 0.5-30?M,and the detection limit was 0.1?M.We have also successfully applied this method to the detection of mercury ions concentration in lake water samples.