Synthesis And Application Of Noble Metal Nanoparticle/Microgel Composites

Noble metal nanoparticle/microgel composites have unqiue properties for noble metal nanoparticles such as good optical properties, biocompatibility, and catalytic properties, etc. By complexing with intelligent polymers or functional polymers, the composites can vary in response to external stimulus, or have functional groups, which make it further functional. So they have potential applications in intelligent catalysis, biosensors, drug delivery analysis, testing, etc.In this article, Noble metal nanoparticle/microgel composites were synthesized. Then the properties of nanocomposite were investigated using UV-vis spectrophotometry(UV-Vis), Fluorescence spectra(FL), Transmission electron microscopy(TEM), Scanning electron microscope(SEM), Thermogravimetric analysis(TGA) and Dynamic laser light scattering(DLS). By using the interaction of noble nanoparticles with fluorescent groups(FRET and MET), ion detection were achieved. The research work and the valuable results are as follows:1.Hybrid microgels with Au nanoparticles(Au NPs) immobilized in poly(N-isopropylacrylamide-co-2-(dimethylamino)ethyl methacrylate)(P(NIPAM-co- DMA)) microgels have been prepared and employed for the detection of Hg2+ ions. The hybrid microgels possess excellent thermo- and pH-responsive properties as well as good stability. 1-pyrenebutyric acid(PBA) molecules were adsorbed on the AuNPs surface via the electrostatic interaction, which leads to fluorescence quench of PBA due to a high-efficiency fluorescence resonance energy transfer from PBA to AuNPs. This PBA-microgels was used as a sensor for Hg2+ assay. The Hg2+ ions replace PBA molecules around Au NPs and form an amalgamation with Au, resulting in a remarkable turn-on fluorescence enhancement. Experimental results show that the increase in fluorescence intensity presents a linear relationship with Hg2+ concentration in the range of 0 to 1.6 ?M with detection limit of 31 nM. Meanwhile, relevant metal ions have no influence on the detection of Hg2+, suggesting a good selectivity for Hg2+ sensing.2.Polydopamine coated sliver nanoparticles were synthesized with dopamine as the reducing agent. The polydopamine coated AgNPs and aminophenyl boronic acid-functionalized Cd Se QDs were assembled into AgNPs-Cd Se QDs complexes through the formation of boronate ester bond. As a result, the fluorescence enhancement and clear blue-shift of the emission peak for Ag NPs-CdSe QDs complexes was observed, which is attributed to the surface plasmon resonance of AgNPs. With the addition of Cu2+ ions, the fluorescence of Ag NPs-CdSe QDs was quenched, along with a red-shift of the emission peak, which was likely to be the formation of insoluble CuSe. Experimental results show that both the decrease in fluorescence intensity and the change of fluorescence emission peak present a linear relationship with Cu2+ concentration in the range of 0 to 325 nM with detection limit of 9.7 nM.