Study On Preparation And Catalytic Detection Performance Of Datomycin Stabilized PdAu And PdPt Nanoenzyme

Most of enzymes are a class of proteins with catalytic activities.However,they are easy to be inactivated due to structural changes in non-physiological environments.Consequently,scientists have been seeking for artificial enzymes for wider applications.Currently,due to the unique properties,nano-materials have attracted widespread attention.Moreover,compared with single metal component nanomaterials,bimetallic nanomaterials with synergistic effect usually show enhanced biomimetic enzyme activity.In this paper,Pd Au and Pd Pt nanoparticles were prepared with daptomycin as a stabilizer and biological template.Their particle sizes,stability,enzyme-like activities,catalytic detection,catalytic reduction of 4-nitrophenol and photothermal conversion properties were studied.First of all,a series of Pd_nAu-Dap NPs with different n values was prepared.Then the structural properties of Pd_nAu-Dap NPs were characterized to confirm the successful preparation of nanoparticles.And it was found that Pd₃Au-Dap NPs had the highest peroxidase-like activity at p H=4 and 30^oC.Through the subsequent dynamic experiments,K_m and V_m of Pd₃Au-Dap NPs to TMB were calculated as 0.6 m M and38.73?10^-8 M·s^-1,then the generation of hydroxyl radical was demonstrated as the catalytic mechanism.More importantly,based on the interaction between S^2-and[Pd₃Au-Dap NPs+H₂O₂+TMB]system,a kind of convenient S^2-colorimetric determination method was established.The detection range and the detection limit of S^2-were 0-70μM and 0.58μM respectively.Through the determination in lakes and seawater samples,the S^2-recovery rate range was obtained between 101.8%-109.8%,demonstrating that the system had certain practical value for the detection of S^2-.In addition,Pd₃Au-Dap NPs had good abilities for catalytic reduction of 4-nitrophenol and photothermal conversion,and the photothermal efficiency is 39.84%.In order to further study the effect of Pt and Pd combination on its catalytic detection performance,daptomycin stabilized Pd Pt nanoparticles were prepared.Through a series of structural characterization,the successful synthesis of Pd Pt_n-Dap NPs was confirmed.After that,POD-like and OXD-like activities of Pd Pt_n-Dap NPs were found out.Then the optimal reaction conditions for biomimetic enzymes were determined as p H=4,40^oC and n=3.The activity mechanism of Pd Pt₃-Dap NPs POD-like is to catalyze the generation of·OH from H₂O₂,while the OXD-like activity mechanism is to catalyze the generation of superoxide anions and singlet oxygen from dissolved oxygen.POD-like dynamic experiments found that the K_m and V_m of Pd Pt₃-Dap NPs to TMB were 0.432 m M and 53?10^-8 M·s^-1,respectively,which was better than those of Pd₃Au-Dap NPs(0.6 m M and 38.73?10^-8 M·s^-1).Subsequently,based the OXD-like activity of Pd Pt₃-Dap NPs,a reliable method of glutathione（GSH）detection was established,the detection range is 0-400μM,the detection limit is 3.51μM.Through the determination in milk samples,the GSH recovery range was obtained between 92.90-107.27%.In addition,Pd Pt₃-Dap NPs could effectively catalyze the reduction of 4-nitrophenol and have good photothermal conversion capacity with a photothermal efficiency of 38.89%.