Controlled Preparation And Application Of Glutathione Capped Metal Nanoclusters

As a new type of nanomaterial,Metal Nanoclusters(MNCs)is increasingly known and valuable for research due to their unique optical properties and excellent performance in various fields such as bioimaging,bio-detection,ion detection and catalysis.Although great progress has been obtained in the development of MNCs,there are still some aspects of research that need to be strengthened.For example,there is a lack of research on metal nanoclusters with near-infrared fluorescence emission and the fluorescent probes based on it or the metal nanoclusters with strong catalytic ability.For the above problems,in our study:Firstly,a controlled method to prepare glutathione-protected bimetallic gold-platinum nanoclusters(Au-Pt NCs@GSH)has been established in the present study.The Au-Pt NCs show either strong red(625 nm)or near-infrared(NIR,805 nm)emission.Further characterizations indicate the average particle size grows from 1.42to 1.78 nm is the main difference between them as large particle size is conducive to redshift of emission.And the NIR emitted Au-Pt NCs are applied as a novel ratiometric probe of Ag(I).It will induce a new emission peak located at 635 nm while quenching the original fluorescence emission during the detection of Ag(I).The response mechanism is attributed to that the added Ag(I)has been reduced by the core of Au-Pt NCs and deposited on the surface,which induces new fluorescence emission around635 nm.The determination shows very high selectivity toward Ag(I)and the limit of determination is10 n M and the linear range is 0.10 to 15mM.In addition,the ratiometric method is feasible for Ag(I)determination in serum with good recovery rates(between98.3%and 102.0%,n=3),showing very high application potential.The present study provides a controlled method to prepare Au-Pt NCs with red and NIR emission and supplies a novel NIR ratiometric probe of Ag(I).Secondly,in the present study,glutathione capped gold and platinum bimetal nanoclusters(Au-Pt NCs)have been prepared and optimized through employing hydrothermal method and adjusting the ratio of raw materials,reaction temperature and heating time.Compared with the corresponding monometallic gold and platinum nanoclusters,the catalytic activity of bimetal nanoclusters is improved significantly for the reaction of TMB with H₂O₂.And the maximum velocity is calculated to be106×10^-8 m M?s^-1 for TMB as substrate,being much better than the majority of reported metallic nanoclusters and nanoparticles in catalysis.Further study shows that the Au-Pt NCs with an average core size at 2.39 nm,and the high catalytic activity is mainly attributed to the synergistic effect of gold and platinum.In addition,they have been applied to detect H₂O₂ in the presence of TMB,and the LOD is 100 n M.Especially,the proposed method has been used to detect H₂O₂ in milk and contact lens solutions,which shows very good recovery exhibiting high practical application potential.Therefore,the present study provides a new type of gold and platinum bimetal nanoclusters with high peroxidase-like activity,which will inspire more research interests on doping and bimetaling with Pt to improve the catalytic activity of metal nanoclusters.