Study On The Biomimetic Enzymes And Detection Properties Of Lentinan Stabilized Noble Metal Nanoparticles

Noble metal nanomaterials were widely used in the field of biomimetic enzyme catalytic detection due to their simple preparation and unique catalytic,optical,electronic and other related properties.However,there are still considerable challenges in preparing precious metal nanomaterials that are environmentally friendly and can exhibit excellent catalytic performance.Therefore,it is necessary to find a method to prepare nanomaterials with uniform particle size and high biocompatibility,this is of great significance for the application of noble metal nanomaterials in the field of biocatalysis detection.In this study,sodium tetrachloropalladate and potassium tetrachloroplatinate were used as metal precursors,and lentinan was used as a green reducing agent and stabilizer to synthesize three noble metal nanomaterials,namely palladium nanoparticles,platinum nanoclusters and palladium@platinum nanodendritic particles were characterized by a series of structure and performance.Based on the biomimetic enzyme properties of precious metal nanomaterials,the content of hydrogen peroxide,glucose,and cysteine molecules in the actual samples were detected.The main contents and conclusions are as follows:Lentinan was used as a biological template,palladium nanoparticles of 2.35±0.57 nm and platinum nanoclusters of 1.20±0.29 nm were prepared.XPS was used to prove the existence and valence of C,O,Pd,Pt elements,and DLS was used to determine that the palladium nanoparticles and platinum nanoclusters in different environments had good solution stability.Enzyme activity experiments was used to prove that platinum nanoclusters prepared with lentinan as a template had higher biomimetic peroxidase activity than platinum nanoparticles.In the catalytic kinetic experiment,the Michaelis constants of palladium nanoparticles and platinum nanoclusters for the substrate tetramethylbenzidine(TMB)were 3.0 m M and 0.584 m M,respectively.In order to better improve the catalytic reaction activity,after optimization experiments,it was finally determined that the optimal catalytic reaction temperature of palladium nanoparticles was 30°C and the optimal p H was4.The optimal catalytic reaction temperature of platinum nanoclusters was 40°C,and the optimal p H was 4.In addition,the survival rate of cells incubated with these two noble metal nanomaterials prepared with lentinan as a template was measured by the MTT method to be more than 90%,which proved that the two noble metal nanomaterials prepared with lentinan as a template had both good biocompatibility.In the end,the two materials were successfully used to detect hydrogen peroxide in cells and the content of glucose in serum,with detection limits of 4.714 μM and 1.79 μM,respectively.In order to develop more precious metal nanomaterials with biomimetic enzyme activity,a series of palladium@platinum nanoparticles were further prepared using lentinan,and palladium@platinum nanodendritic particles were prepared by adjusting the molar ratio of palladium and platinum to 1:3,with a particle size of 10.76±1.82 nm.The nanoparticles had a special morphology and was uniformly dispersed.Through XPS,EDS,XRD analysis,its elemental composition was C,O,Pd,Pt and the surface contains four crystal planes(111),(200),(220),(311).Next,DLS was used to determine the average hydrodynamic size of the material under different environments,which was 25.7 nm.Enzyme activity verification experiments showed that palladium@platinum nanodendritic particles had better biomimetic oxidase activity than single metal palladium or platinum nanoparticles.Catalytic kinetic experiments showed that the Michaelis constant of the palladium@platinum nanodendritic particles against the substrate TMB was 0.263 m M.In order to better improve the catalytic reaction activity,after optimization experiments,it was finally determined that the optimal catalytic reaction temperature of palladium@platinum nanodendritic particles was 40°C and the optimal p H was 4.Finally,the nanomaterial was used to establish a standard curve for the detection of cysteine.The linear range and detection limit were 0-200 μM and 3.099 μM,respectively.They were successfully used to detect the content of cysteine in milk.The above research results confirmed that LNT was an ideal biological template.It can not only simply prepare stable nanoparticles,but also effectively improve their biocompatibility,which is convenient for expanding the research of catalytic detection in the field of biomedicine and laying the foundation for the timely diagnosis of certain human physiological diseases.