Synthesis And Applications Of Noble Metal-Protein Core-Shell Nanomaterials

Nanoparticles(NPs)have attracted a great deal of attention due to their fascinating properties and potential applications in nanotechnology and bio-technology.The discovery of nanozymes(nanomaterials with enzyme-like characteristics)has promoted the foundation of nanotechnology research and expanded the application of nanometer materials.In order to overcome the reunion and settlement of nanomaterials,protein-directed synthetic route for nanomaterials has become the focus of the recent chase.The protein shell can help and offer the desired shape,size,and solubility to nanomaterials.At the same time,protein shell may also determine the protein related functions of nanomaterials,such as biomarkers,catalytic function,identification,fluorescence enhancement and so on.The paper will be divided into three chapters:Chapter 1: Synthesis and peroxidase-Like activity of platinum nanoparticles by using bovine serum albumin as the scaffold.This chapter has demonstrated the synthesis of PtNPs in the BSA scaffold through biomineralization.The protein shell can help and offer the desired shape,size,and solubility.This chapter has studyed the peroxidase-like characteristics and stability of BSA-PtNPs.Result: The resulting BSA-PtNPs demonstrated intrinsic peroxidase-like activity,which could catalytically oxidize various substrates in the presence of H2O2.This new type of enzyme mimic show a much higher affinity(by at least 1 order of magnitude)for H2O2 than the NPs of other Pt-based peroxidase mimics owing to the role of the protein shell.The most important thing was that the BSA shell plays an important role in promoting the robust stability of PtNPs.Even in high ionic strength environment(2 M NaCl)and high concentration of proteins(150 mg/mL),the catalytic activity could be completely preserved.Chapter 2: The sensitization effect of bismuth on the peroxidase-like of BSA-PtNPs and the high-sensitive detection of sulfur ions.This chapter has demonstrated Bi atoms/ions can be adsorbed on the BSA-PtNPs into Bi/BSA-PtNPs by some reduction reaction,leading to enhanced peroxidase-like activity.This approach could be extended for the detection of S2-based on the system of Bi/BSA-PtNPs-TMB-H2O2 and the inhibition of peroxidase-like activity induced by Pt-S.Result: The Bi atoms/ions adsorbed on the BSA-PtNPs could successfully enhance the peroxidase-like activity of BSA-PtNPs.For the detection of S2-,linearity was obtained to be 0.08~4 ?M(y=0.17159+0.17008 x,r=0.9959),the limit of detection(LOD)of S2-was 50 nM(with a signal-to-noise ratio of 3).This work could be successfully applied to the recoveries of water samples with good specificity and short detection time.In comparison with some established methods to detect S2-,this work has the advantages of lower LOD,wider linear range,etc.Chapter 3: Synthesis,properties and application of avidin functionalized fluorescent gold nanoclustersIn this chapter,Av-AuNCs with great perxidase-like activity have been obtained by using avidin as scaffold through biomineralization.This nanomaterial has stable fluorescence.The avidin-shell not only provides stability,but also determines the Av-AuNCs may have related functions with avidin itself.We found that Av-AuNCs could catalyze the oxidation of TMB in the presence of H2O2 to produce a blue product with a maximum absorbance at 652 nm as peroxidase.By fluorescence spectrophotometry(excited at 387 nm),the Av-AuNCs solution exhibited strong fluorescence around 460 nm and 650 nm.The quantum yield(QY)of Av-AuNCs was0.82 %.By means of the recognition of biotin in liver cancer cells and the method of sandwich-type DNA biosensor probe(DNA hybridization/cryptococcal/ssDNA),this work has proved that the avidin-shell in Av-AuNCs could recognize and bind to biotin.