SYNTHESIS OF GOLD NANOPARTICLES SUPPORTED ON FUNCTIONALIZED SILICA NANOPARTICLES

Gold nanoparticles (AuNPs) are among the most intensely studied nanoscale materials, finding numerous applications in several fields such as catalysis, biomedicine and microelectronics. [1] AuNPs can be synthesized by several chemical procedures reported in literature, where in general the Au(III) precursor is reduced by a reducing agent and the AuNPs formed stabilized by the use of a stabilizing agent. [2] Recently, we presented stable silica-supported gold nanoparticles suitable for catalysis, obtained by using as the only reactants a gold precursor, chloroauric acid (HAuCl4), and commercial polyethyleneimine-functionalized silica beads (SiO2-PEI), with the need for neither external reducing agents nor conventional stabilizing moieties. [3] In this work we describe another convenient method to prepare functionalized-silica nanoparticles able to reduce in situ HAuCl4 precursor. The silica nanoparticles were synthetized, first, by co-condensation of tetraethoxysilane and an organo-silane alkyne-terminated (PPTEOS) (SiO2-Yne) [4] and then post-functionalized by thiol/yne coupling with cysteamine, silica nanoparticles SiO2-Thio-Yne are obtained with sulphide and primary amine, known for their capability to stabilize gold nanoparticles. [5] . Scheme 1. Synthesis of alkyne-modified silica nanoparticles and subsequent thiol/yne coupling. By simply adding an aqueous solution of HAuCl4 to SiO2-Yne (d 77 ± 10 nm) or to SiO2-Thio-Yne we achieved in both case AuNPs anchored on the silica surface. These systems were fully-characterized by FT-IR, XPS spectroscopy, DLS ,UV-Vis, TOF-SIMS and TEM microscopy.