Protein Functionalized Platinum And Its Composite Materials To Simulate Enzyme Properties And Visual Sensing Applications

With the rapid development of nanotechnology,new artificial enzyme(nanozymes)of different nanomaterials has attracted more and more attention.The stability and catalytic activity of nanozymes is the key to their application in chemical and biological application.Platinum nanomaterials have excellent catalytic activity,but poor stability,high cost and scarce reserves limit their applications in many fields.In this paper,platinum based nanozyme with high activity,high stability and multifunction was constructed by using biomolecules and inorganic materials to functionalize platinum nanoparticles.Furthermore,its analytical application in environmental and biological was also studied.1.Switching peroxidase-mimic activity of ?-casein stabilized Pt nanozymes by sulfide:mechanism,substrate dependence and detectionIn the present work,we use ?-casein as a model protein to prepare a smart P-casein stabilized Pt nanoparticle(CM-Pt NPs)with peroxidase mimicking activity,and systematically investigate,sulfide-mediated switching effect and mechanism of CM-Pt NPs nanozyme's activity.Sulfide-mediated activity switching effect depends heavily on the physicochemical properties of nanozymes and the identity of substrate.On one hand,the binding of sulfide to Pt nanozyme surface leads to the transform from Pt2+ to Pt0,resulting in more active sites and the activity"switching on",on the other hand,the binding of sulfide ions via Pt-S interaction blocks the active sites,resulting in the activity "switching off".For substrates 3,3',5,5'-tetramethylbenzidine(TMB)and 2,2'-azinobis(3-ethylbenzthiazoline-6-sulfonic acid)diammonium salt(ABTS),the two factors play different decisive roles since the interaction of substrate molecules with nanozyme allows their different distributions on nanozyme surfaces.By virtue of this specific response,excellent sulfide colorimetric sensors with different limit of detection(LOD)and linear range was developed based on CM-Pt NPs with different substrates.2.Peroxidase-mimic activity of ?-casein functionalized BiPt nanochain/GO compositenanomaterials and a step method to detect glucose visuallyA new nanohybrid-of BiPt nanochain/graphene oxide composite(CM-BiPt NC/GO)was prepared via a facile one-pot approach by using ?-casein as the stabilizer.?-casein functionalized BiPt/GO composite possess attractive peroxidase mimicking property.They can efficiently catalyze the oxidation of 3,3,5,5-tetramethylbenzidine(TMB)in the coexistence of hydrogen peroxide(H2O2).The limit of detection was calculated as low as 0.01 ?M(S/N = 3)and the linear range of hydrogen peroxide was 0.01-1500 ?M.On the basis of these findings,we developed a new highly sensitive colorimetric single-step method for glucose detection,and the limit of detection was calculated as low as 0.05 ?M(S/N = 3),the linear range was 0.5-1000 ?M.Further application of the present system for glucose detection in human serum has been successfully demonstrated,suggesting its promising utilization as robust peroxidase mimics in the clinical diagnosis,pharmaceutical,and environmental chemistry fields.3.Peroxidase-mimic activity of ?-Casein functionalized Pt/Fe3O4 composite nanomaterials and one step method for visually detect cholesterol.Cholesterol in human fluids is a clinically important analyte and its sensitive detection is significant in diagnosis.CM-Pt/Fe3O4 nanoparticles prepared by in situ growth of Pt nanoparticles(Pt NPs)on the surface of Fe3O4 nanoparticles have been successfully applied to fabricate a colorimetric biosensing platform for cholesterol.In the presence of cholesterol,H2O2 was produced under the catalytic action of their corresponding enzymes such as cholesterol oxidase(ChOx),which etched the CM-Pt/Fe3O4.Respectively,under optimum conditions,the linear ranges for the detection of H2O2 and cholesterol by UV-vis spectroscopy were from 0.01-1000 ?M and 0.1-400 ?M.The detection limit of the biosensors for H2O2 and cholesterol were 1 nM and 50 nM(S/N = 3),respectively.This work provides a siimple and sensitive approach for cholesterol detection,which has broad application prospects in clinical diagnosis.