Fluorescence Sensing Based On Gold,Silver Nanoparticles And Related Composites

Gold and silver nanoparticles have been widely applied in fields of material,information and life science due to their particular optical,electric and chemical properties.Thus,the preparation and application of gold and silver nanoparticles and their composites have become one of the hot research topics in modern science.In this paper,new water-soluble conjugated polymer stablized-silver nanoparticles and sodium citrate protected-gold nanoparticles were synthesized.Based on the interaction between gold or silver nanoparticles and pyrene derivative probe,we systematically investigated the fluorescence sensing of iodide,biothiols and thiocyanate with high sensitivity.The following is the main contents of my dissertation:(1)P1,a novel conjugated polymer with specific coordinating pyridyl segments,was chosen as the protective agent for AgNPs.The P1-AgNPs prepared by in situ synthesis.The intense fluorescence of probe 1 can be quenched owing to the inner-filter effect(IFE)of P1-AgNPs on pyrene derivative(probe 1).Then the intense fluorescence of probe1 quenched by P1-AgNPs can be efficiently recovered after the addition of H2O2and I-via the Pl-AgNPs oxidation-etching and damping of surface plasmon band.The lowest detectable concentrations of I-using this method was 5.0×10-10 M.(2)The AuNPs were prepared through Frens method coated with citrate.The fluorescence of pyrene derivative(probe 1)absorbed on the surface of the gold nanoparticles gets quenched owing to the surface energy transfer from the probe 1 to the gold nanoparticles.After addition of biothiols,the strong covalent combination between the mercapto group of biothiols and gold nanoparticles drives probe 1 away from the gold nanoparticles’surface,which block the pathway of energy transfer between probe 1 and gold nanoparticles.Based on this phenomenon,we build a sensitive method for biothiols detection.The lowest detectable concentrations of biothiols using this method was 1.0×10-9 M.(3)A convenient fluorescent sensor based on the citrate coated AuNPs and pyrene derivative(probe 1)was demonstrated for thiocyanate(SCN-).As mentioned,the fluorescence of pyrene derivative(probe 1)was quenched by gold nanoparticles.With addition of SCN-,SCN-absorbs on the surface of AuNPs with non-covalent means which drives probe 1 away from the gold nanoparticles’ surface though competition response between SCN-and probe 1.As a result,the intense fluorescence of probe1 quenched by AuNPs can be efficiently recovered.Based on this phenomenon,we build a simple and sensitive method for SCN-detection.The lowest detectable concentrations of SCN-using this method was 3.0×10-7M.