F. Liebig, R. M. Sarhan, C. N.Z. Schmitt, A. F. Thünemann, C. Prietzel, M. Bargheer, J. Koetz
Gold Nanotriangles with Crumble Topping and their Influence on Catalysis and Surface-Enhanced Raman Spectroscopy
ChemPlusChem 2020, 85, 519-526
DOI: 10.1002/cplu.201900745
By adding hyaluronic acid (HA) to AOT-stabilized gold nanotriangles (AuNTs) with an average thickness of 7.5 ± 1 nm and an edge length of about 175 ± 17 nm the AOT-bilayer is replaced by a polymeric HA-layer leading to biocompatible nanoplatelets. The following reduction process of tetrachloroauric acid in the HA-shell surrounding the AuNTs leads to the formation of spherical gold nanoparticles on the platelet surface. With increasing tetrachloroauric acid concentration the decoration with gold nanoparticles can be tuned. SAXS measurements reveal an increase of the platelet thickness up to ~14.5 nm, twice to the initial one of bare AuNTs. HRTEM micrographs show welding phenomena between densely packed particles on the platelet surface, leading to a crumble formation while preserving the original crystal structure. Crumbles crystallized on top of the platelets enhance the Raman signal by a factor of ~20, and intensify the plasmon-driven dimerization of 4-nitrothiophenol (4-NTP) to 4,4\'-dimercaptoazobenzene up to a yield of 50%. The finally received crumbled nanotriangles, with a biopolymer shell and the absorption maximum in the second window for in vivo imaging, are promising candidates for biomedical sensing.
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