Study On The Mimetic Enzyme Properties Of Noble Metal Nanoparticles And Their Application In Glucose Detection

The natural peroxidase has high catalytic activity and selectivity in the catalytic reaction,which is important biocatalyst and is used in various biochemical assays.However,it has many disadvantages such as easy to inactivate and expensive,and the development of artificial mimic enzymes with catalytic activity similar to natural enzymes is one of the solutions to thses problems.The noble metal nanoparticles can effectively mimic the function of peroxidase and catalyze the substrate of peroxidase.The particle size and stability of noble metal nanoparticles have a significant effect on their catalytic properties.Therefore,the noble metal nanoparticles having small size and stability have better catalytic performance.In this paper,two kinds of reducing natural polysaccharides?auricularia polysaccharide and ganoderma lucidum polysaccharide?were used as biological templates to prepare polysaccharide-stabilized palladium and platinum nanoparticles,and they were used as mimetic enzymes in the detection of glucose concentration.The specific research contents are as follows:?1?Based on the stability and reducibility of natural polysaccharides in aqueous solution,polysaccharide-stabilized noble metal nanoparticles were prepared by controlling the ratio of polysaccharides of auricularia and ganoderma lucidum to noble precursors?sodium tetrachloropalladate and potassium tetrachloroplatinate?.The metal nanoparticles sizes of agaricularia polysaccharide-stabilized nanopalladium?AP-Pd_n NPs?,agaricularia polysaccharide-stabilized nanoplatinum?AP-Pt_n NPs?,ganoderma lucidum polysaccharide-stabilized nanopalladium?GLP-Pd_n NPs?and ganoderma lucidum polysaccharide-stabilized nanoplatinum?GLP-Pt_n NPs?were 1-2 nm,2-4 nm,5-6 nm,and 1-3 nm,respectively.These polysaccharide-stabilized noble metal nanoparticles had good stability in aqueous solution.?2?These polysaccharide-stabilized noble metal nanoparticles catalyzed the oxidation of 3,3',5,5'-tetramethylbenzidine?TMB?to the blue product?oxTMB?in the presence of hydrogen peroxide?H₂O₂?,indicating their peroxidase-like activity.The kinetic equations of these reactions followed Michaelis-Menten equation.The AP-Pd_n NPs,AP-Pt_n NPs and GLP-Pt_n NPs had smaller Michaelis constants?K_m?for TMB and H₂O₂ than HPR,while GLP-Pd_n NPs only have a smaller K_m for H₂O₂ than HPR,indicating they had higher affinity for these substrates than HRP.The catalytic mechanism of these reactions followed the ping-pong mechanism.?3?The polysaccharide-stabilized noble metal nanoparticles were used to establish four colorimetric methods for glucose detection based on catalytic oxidation of TMB and the generation of H₂O₂ by glucose oxidase.The detection method established by using the AP-Pd_n NPs has the linear range of 0.04-0.9 mM and the detection limit of 10?M.The detection method established by using the AP-Pt_n NPs has the linear range of 0.04-1mM and the detection limit of 7?M.The detection method established by using the GLP-Pd_n NPs has the linear range of 0.04-1 mM and the detection limit of 20?M.The detection method established by using the GLP-Pt_n NPs has the linear range of 0.1-1 mM and the detection limit of 11?M.These methods have been successfully applied to detect the glucose concentration in real samples.