A novel method for the synthesis of monodisperse gold-coated silica nanoparticles |
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Authors: | Michael D English and Eric R Waclawik |
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Institution: | (1) Faculty of Science and Technology, Chemistry Discipline, Queensland University of Technology, Brisbane, 4000, Australia; |
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Abstract: | Monodisperse silica nanoparticles were synthesised by the well-known Stober protocol, then dispersed in acetonitrile (ACN)
and subsequently added to a bisacetonitrile gold(I) coordination complex (Au(MeCN)2]+) in ACN. The silica hydroxyl groups were deprotonated in the presence of ACN, generating a formal negative charge on the
siloxy groups. This allowed the Au(MeCN)2]+ complex to undergo ligand exchange with the silica nanoparticles and form a surface coordination complex with reduction to
metallic gold (Au0) proceeding by an inner sphere mechanism. The residual Au(MeCN)2]+ complex was allowed to react with water, disproportionating into Au0 and Au(III), respectively, with the Au0 adding to the reduced gold already bound on the silica surface. The so-formed metallic gold seed surface was found to be
suitable for the conventional reduction of Au(III) to Au0 by ascorbic acid (ASC). This process generated a thin and uniform gold coating on the silica nanoparticles. The silica NPs
batches synthesised were in a size range from 45 to 460 nm. Of these silica NP batches, the size range from 400 to 480 nm
were used for the gold-coating experiments. |
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