Study On Preparation,Stability And Glucose Detection Performance Of Ultrafine Platinum Nanozyme

Noble platinum nanoparticles have good peroxidase-like activity and can be used for the glucose detection of a variety of samples.However,the dispersibility and size of platinum nanozymes will seriously affect their catalytic activity,especially for the detection of glucose concentration in complex media containing protein molecules.Therefore,it is very important to prepare platinum nanozymes with high dispersibility and small size by water-soluble polymers and use platinum nanozymes to detect glucose concentration in complex media.In this paper,from the perspective of green chemistry and improving the stability of platinum nanozymes in protein solution,it was focused on the stability in aqueous solutions,catalytic activity,stability in protein solutions,cytotoxicity and glucose detection abilities of platinum nanozymes stabilized by water-soluble natural polysaccharides(Ginkgo biloba leaf polysaccharide,Polygonum multiflorum thunb polysaccharide and longan polysaccharide).The performance of human blood glucose detection was initially verified.Spherical zwitterionic dendrimers by surface modification stabilized platinum nanozymes had good blood glucose detection results and highly sensitive detection limit.The main contents and conclusions are as follows:(1)Linear polyethyleneimine molecule was used as the template and sodium borohydride was used as the reducing agent to prepare platinum nanoparticles(Ptn-PEI NPs)with the size ranging from 3.21-3.70 nm.The hydrodynamic sizes of Ptn-PEI NPs didn?t change significantly within 7 days and Ptn-PEI NPs catalyzed 3,3',5,5'-tetramethylbenzidine(TMB)to turned blue;the catalytic kinetic process followed Michaelis-Menten equation;the detection limit of glucose concentration by colorimetry in acetic acid-sodium acetate solution was 4.2 ?M.Pt50-PEI NPs had low catalytic activity for TMB,induced fibrinogen precipitation and cell death,can?t be used to detect blood glucose concentration in plasma.Therefore,it was found that the biocompatibility of nanozymes should be considered in the blood glucose testing process.(2)To address the problem of low biocompatibility exhibited by Pt50-PEI NPs,platinum nanoparticles(Pt-GBLP NPs)stabilized by highly biocompatible Ginkgo biloba polysaccharides with the size of 1.08±0.16 nm were prepared.The color of TMB solution catalyzed by Pt-GBLP NPs turned blue and the 7-day hydrodynamic sizes of Pt-GBLP NPs didn?t change significantly;this process followed the ping-pong mechanism.The method of colorimetric glucose detection using Pt-GBLP NPs in acetic acid-sodium acetate buffer had a linear range of 1-1000 ?M and a detection limit of 0.5 ?M.500 ?g/m L Pt-GBLP NPs showed no cytotoxicity to He La cells,but induced fibrinogen to form aggregates,resulting in accuracy of only 90-91% for blood glucose detection.(3)In order to solve the problem that Pt-GBLP NPs induced obvious aggregation of fibrinogen,from the perspective of increasing the content of glucose units,platinum nanoparticles(Ptn-PMTP NPs and Pt-LP NPs)were stabilized by Polygonum multiflorum thunb polysaccharide and longan polysaccharide,respectively.They had the size within 1.05-1.48 nm and exhibited obvious peroxidase-like activity;their hydrodynamic sizes didn?t change significantly within 7 days.Pt20-PMTP NPs and Pt-LP NPs had the linear range of glucose concentration in acetic acid-sodium acetate buffer for 1-1000 ?M,and the detection limits were 0.2 ?M and 0.35 ?M,respectively.The 500 ?g/m L samples almost had no cytotoxicity to He La cells,but there was weak aggregation in the fibrinogen solution for a long time.The accuracy of blood glucose concentration detected by this method was 95%.(4)In order to further improve the stability of nanozymes in fibrinogen,zwitterionic dendrimers(G5MEKn C)were prepared by surface modification of generation 5 poly(amido amine)dendrimers using maleic anhydride,EK-5 and cysteamine.The size of platinum nanozyme(Pt55-G5MEK50C)prepared by sodium borohydride reduction was only 1.40 nm.Pt55-G5MEK50 C had peroxidase-like activity.The linear range of Pt55-G5MEK50 C to detect glucose concentration was 1-2000 ?M,and the detection limit was 0.1 ?M,which was the lowest detection limit obtained in this work.This value was also lower compared with existing related literature.The He La cell viability of the samples was bigger than 90% and the samples had good stability in protein solution within 4 days.The preliminary human blood glucose test showed that,compared with the results of the medical automatic biochemical analyzer,the accuracy of this method for detecting blood glucose in this chapter was 98%.The catalytic mechanism was the decomposition of hydrogen peroxide catalyzed by Pt55-G5MEK50 C to generate hydroxyl radicals which accelerated the oxidation of TMB.