Study On Platinum Nanoparticles-Graphene Oxide Hybrid With Excellent Peroxidase-Like Activity

In recent years,artificial enzymes have received great attentions in the field of material science,biomedicine,environmental chemistry and physics.They not only exhibit the advantages of cost-efficiency,acid and alkali resistance,high stability,and high temperature resistance,but also possess lower sensitivity to proteases and less susceptible to degradation and so on.Graphene oxide（GO）is a class of promising two-dimensional carbon nanomaterial.Due to its special performance with the base surface containing oxygen-rich functional groups,GO is good biocompatibility and water solubility.Recently,functional studies on graphene oxide as a scaffold have become the spotlight.Using chemical reactivity of the functional groups,a series of biosensors can be established,which greatly broaden the applications for biomedical detection.This article provides the PtNPs-GO hybrid with high affinity for substrates,good stability and excellent intrinsic peroxidase-like activity.The basic properties and chemical analysis application of the resulting PtNPs-GO nanocomposite are also demonstrated.The paper is divided into three parts.Chapter 1: Synthesis and characteristrics of PtNPs-GOA facile approach is proposed for in-situ growth of platinum nanoparticles on graphene oxide（PtNPs-GO）functioned as the scaffold,trying not to destroy the characteristics of platinum nanoparticle.It is worth noting that the synthetic process is green,straightforward and extremely fast.The prepared PtNPs well distribute only on the surface of the graphene oxide,and no other forms of by-product are generated.Besides,the resulting PtNPs-GO composites possess small particle size of PtNPs.Taken together,current method exhibits the performance of good reproducibility toobtained products with high aqueous dispersion and stability.Chapter 2: Peroxidase-like activity of PtNPs-GOIn this work,we further explore that the as-synthesized PtNPs-GO nanomaterials possess excellent peroxidase-like activity.Colorimetric tests have been carried out through employing the H₂O₂-mediated oxidation of typical chromogen substrates of horseradish peroxidase,including TMB,ABTS,OPD,4-AAP/Phenol,and DAB.Kinetic studies indicate that the PtNPs-GO hybrid has a much higher affinity to both TMB and H₂O₂ than those of other platinum-based peroxidase mimics.Accordingly,the water-soluble PtNPs-GO is used to detect low concentrations of H₂O₂.Absorbance of the catalyzed product has a good linear correlation with the concentration of H₂O₂ in the range of 0.1-25 mM.The limited of detection is 0.036 mM.Chapter 3: PtNPs-GO for colorimetric detection of L-cysteineIn this chapter,colorimetric recognition and sensing of L-cysteine with high sensitivity and selectivity is presented based on target-induced shielding against the peroxidase-like activity of PtNPs-GO in the PtNPs-GO/H₂O₂/TMB system.Available L-cys concentration could be acquired by detecting colorimetric signal chage of L-cys/PtNPs-GO/H₂O₂/TMB system under appropriate conditions.The results show that the method is convenient and rapid.L-cys with low concentration can be accurately and sensitively detected by UV spectrophotometry.The detection limit is as low as 1.2 nM.We envision that this material will be an ideal candidate for a wide range of potential application in the fields of biomedicine and environmental chemistry.