Preparation Of Gold Nanoparticles On A Solid Substrate And Sensing Of Copper (Ⅱ) Ions

It is essential in many life processes when the copper ion concentration is less than 1μM. Copper element involves in the synthesis of hemoglobin, a variety of enzymes, and the metabolism of the body, so it plays an important role in human health. When its concentration in the organism is too high, it will inhibit some necessary enzymes and make biological oxidation/reduction process abnormal. It can pose serious adverse effects in the liver and gall bladder. Therefore, it is important to develop a method for the highly sensitive, selective, and efficient detection of copper in environmental analysis, food testing and biomedical assay. Noble metal nanoparticles are unique and different with macroscopic matter on the structure and properties. The outer electrons are very active, so it has unique optical phenomena, showing strong localized surface plasmon resonance(LSPR) effect. Currently, the detection method of copper ions based on nanotechnology has received extensive attention of scholars and a lot of research.In the first part,a gold nanoparticle(Au NP) array based plasmonic probe was developed for sensitive and selective detection of Cu2+ ions. The Au NPs were self-assembled on transparent indium tin oxide(ITO) film coated glass substrate using poly dimethyl diallyl ammonium chloride(PDDA) as a linker and then calcined at 400°C to obtain pure Au NP array on ITO surface(ITO/Au NPs). The probe was fabricated by functionalizing L-cysteine(Cys) on to gold surface(ITO/Au NPs/Cys). The strong chelation of Cu2+ with Cys formed a stable Cys-Cu complex, and resulted in the red-shift of localized surface plasmon resonance(LSPR) peak of the Au NPs. The introduction of bovine serum albumin(BSA) as the second complexant could form complex of Cys-Cu-BSA and further markedly enhanced the red-shift of the LSPR peak. This plsmonic probe provided a highly sensitive and selective detection towards Cu2+ ions, with a wide linear detection range(10-11–10-5M) over 6 orders of magnitude. The simple and cost-effective probe was successfully applied to the determination of Cu2+ in real samples.Then we choose another kind of binder. The mixed solution of polyvinyl alcohol(PVA) and gold sol was dropped onto the of transparent indium tin oxide(ITO) and then burned at 600 ℃ in order to obtain pure gold surface of ITO(ITO/Au NPs). We investigated the effect of dispensing volume, temperature and time of the obtained ITO/Au NPs and used UV-visible spectrophotometry, transmission electron microscopy to characterize its structure. Finally prepared gold nanoparticles was used to measure concentration of copper ion after modified with cysteine.