Optical Properties Of Luminescent Gold Nanoparticles And Sensing Of Organic Phosphorus And Selenium Molecules

As a new type of luminescent nanomaterial,luminescent gold nanoparticles have many unique properties such as small size,large specific surface area,large Stoke shift superb biocompatibility,Fast removal rate,high target efficiency,and facile surface functionalization,they are widely used in sensing and biological imaging.Since surface ligands play an important role in the optical properties of gold nanoparticles,a series of small molecule sensing studies can be designed by introducing different ligands to change the fluorescence properties.This paper is based on the interaction between sulfur atom in sulfhydryl molecules and gold,which stronger than the interaction between nitrogen and gold in DNA,but weaker than the combination of selenium and gold in selenol.According to this regular,the detection of organic phosphorus and selenol molecules by luminescent gold nanoparticles is achieved,repectively.which is as follows:The red fluorescent gold nanoclusters(DNA-AuNCs)were prepared by using non-thiol ligand DNA to detect sulfur-containing organophosphorus pesticides.Due to the weak binding of the N atom of DNA to Au in DNA-AuNCs,the stability of such gold nanoclusters(AuNCs)is poor,and it is precisely because of this instability that the detection of sulfhydryl molecule is possible.Organophosphorus pesticides such as chlorpyrifos,methyl parathion,diazinon,and malathion contain two active sites of activated S atom and S atom or S atom and O atom after hydrolysis.When thiol-containing organophosphorus pesticides are added to gold nanoclusters,due to the strong binding ability between Au and S,the DNA in the DNA-AuNCs is replaced,and the S atoms and O atoms on the organic phosphorus combine with different gold atoms,causing agglomeration of gold nanoclusters,thus the fluorescence is quenched.When introducing small molecules such as glutathione and mercaptopropionic acid containing sulfhydryl reagents,the color of the solution becomes colorless gradually and fluorescence quenches,which efficacious distinguish organophosphorus pesticides containing S.And successfully applied to the detection of chlorpyrifos in agricultural productsGS-AuNPs with different surface coverage were prepared for the determination of selenol by adjusting the ratio of ligand glutathione(GSH)to gold.In this paper,GS-AuNPs with nearinfrared luminescence(810 nm)and visible luminescence(610 nm)were synthesized with GSH and Au molar ratios of 0.7 and 1.3,respectively,and the surface ligand densities were 23.0% and 47.6%,respectively.According to this feature,it can be effectively used for selenol detection.For 610 nm luminescent GS-AuNPs with high surface ligand density.810 nm luminescent GS-AuNP has a lower surface ligand density and more surface vacancies.Once selenol is introduced,selenol molecules will enter the surface of gold nanoparticles to form the Au-Se bond,resulting in fluorescence quenching.Hence,according to the intensity of fluorescence changes before and after the introduction of selenocarbon,quantitative detection of selenol can be achieved.The high-molecular coverage of the 610 nm-emitting gold nanoparticles can block the entry of selenol into the surface of the gold nanoparticles,and the fluorescence does not change.In this paper,GS-AuNPs with 610 nm and 810 nm luminescence were mixed in a certain ratio,and a fluorescence probe at a ratio of 610 nm-luminescence was used as a reference to construct a ratiometric fluorescent probe for selenol detection.And this probe successfully used for the detection of selenol content in cell imaging.