Synthesis And Photoanalytical Application Of Metal Nanoclusters

As a new type of nanomaterials,metal nanocluster has advantages of a small size,good stability,big Stokes displacement and good biocompatibility,and has been widely used in analytical chemistry in recent years.ABTS is a catalase substrate,and the oxidation-reduction potential of ABTS / ABTS+ is 0.68 V,which is prone to electron transfer,the generated stable green free radicals can carry out the visual inspection,which has been widely used in biological,chemical and other fields as the optical probes.As the small sequence of oligonucleotide sequences obtained by in vitro screening,aptamer can be highly specific binding with the corresponding target substance,and meanwhile could be used for the synthesis of metal nanoclusters as a template.In this paper,experiments of the preparation,characterization and analysis of metal nanoclusters are mainly completed and the details are as follows:(1)The synthesis of copper nanoclusters with dithiothreitol(DTT)as the template and the silver nanoparticles with stabile citric acid,and methods of UV-visible spectrophotometry and fluorescence spectroscopy have been used respectively for the representation.silver nanoparticles can make the fluorescence of copper nanoclusters quenching through the internal filter effect,after adding melamine,as melamine makes silver nanoparticles agglomerated,the internal filter effect is destroyed and the Copper nanoclusters fluorescence is recovered.An internal filter based on Copper nanoclusters and silver nanoparticles has been constructed for the detection of melamine.The experimental result shows that when the melamine concentration is in the range of 4-28?M,there's a good linear relationship between the degree of fluorescence recovery of the system and the concentration of melamine,the detection limit is 0.98 ?M,and the recoveries of the actual samples(milk)are 96.5%-103.8%.(2)The synthesis of copper nanoclusters with chloramphenicol aptamers as the template,in the action of exonuclease ?(Exo ?),the synthesis of DNA copper nanoclusters causes the failure of the template and fluorescence quenching,meanwhile,under the combined effect of hydrogen peroxide and creatine liver,the divalent copper ions would make ABTS oxidized into green ABTS+,and Exo ? could be detected by fluorescence,ultraviolet and visual inspection.The experimental result shows that when the concentration of Exo ? is 0.1-10 U mL-1,there's a good linear relationship between the fluorescence intensity of the system and the concentration of Exo ?,the detection limit is0.08 U mL-1,and the actual sample(serum)spiked recovery is 92.4%-103.7%.(3)The synthesis of gold nanoclusters with DNA as template,in the action of the Fenton reaction between hydrogen peroxide and ferrous ions,the synthesis of gold nanoparticles causes the failure of the template and fluorescence quenching,meanwhile,the trivalent gold ions will make ABTS oxidized into green ABTS+,and the hydroxyl radicals can be detected by fluorescence,ultraviolet and visual detection.The experimental result shows that when the concentration of hydrogen peroxide is 2-15 ?M,there's a good linear relationship between the fluorescence intensity F0-F of the system and the concentration of hydrogen peroxide.The detection limit is 1.5 ?M,and the recoveries for the actual sample(serum)is 90.6%-108.6%.