Gold Nanotriangles with Crumble Topping and their Influence on Catalysis and Surface‐Enhanced Raman Spectroscopy. Issue 3 (31st January 2020)

• Record Type: Journal Article
• Authors: Liebig, Ferenc; Sarhan, Radwan M.; Schmitt, Clemens N. Z.; Thünemann, Andreas F.; Prietzel, Claudia; Bargheer, Matias; Koetz, Joachim
• Is Part Of: ChemPlusChem. Volume 85:Issue 3(2020)
• Page Start: 519
• Page End: 526
• Publication Date: 2020-01-31
• Subjects: gold nanostructures -- HRTEM -- hyaluronic acid -- monolayer formation -- SERS; Chemistry -- Periodicals; 540.5
• DOI: 10.1002/cplu.201900745
• Languages: English
• ISSNs: 2192-6506

Abstract

Abstract: By adding hyaluronic acid (HA) to dioctyl sodium sulfosuccinate (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 subsequent 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 around 14.5 nm, twice the initial value 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 around 20, and intensify the plasmon‐driven dimerization of 4‐nitrothiophenol (4‐NTP) to 4, 4′‐dimercaptoazobenzene in a yield of up to 50 %. The resulting crumbled nanotriangles, with a biopolymer shell and the absorption maximum in the second window for in vivo imaging, are promising candidates for biomedical sensing. Abstract : Crumble topping : The surface of ultraflat gold nanotriangles with an average thickness of 7.5 nm composed of {111} facets can be coated by the biopolymer hyaluronic acid. Spherical gold nanoparticles are synthesized inside the biopolymer shell, and aggregate to crumbles and crystallize onto the platelet surface. Gold nanotriangles with crumble topping and a platelet thickness of about 14.5 nm are thus formed, and enhance the Raman signal by a factor of 20, and also induce the plasmon‐driven dimerization of 4‐nitrothiophenol.