Photochemical Strategies for the Seed-Mediated Growth of Gold and Gold–Silver Nanoparticles

Gold nanoparticles (AuNP) can be used as seeds for the synthesis of larger AuNP of controllable size with narrow size distribution by photochemical reduction of additional Au­(III) using water-soluble benzoins or H₂O₂ as sources of reducing radicals. Further, beyond simply enlarging the AuNP, it is possible to add a shell of another metal, such as silver, leading to Au/Ag core–shell structures with controllable dimensions for both core and shell. This strategy illustrates the fine spatial and temporal control achievable using clean photochemical techniques without the addition of hard surface ligands often necessary to control the size and structure of gold–silver nanostructures. The mild nature of the surface coverage makes these nanomaterials ideal for further surface modification

Supported Gold Nanoparticles as Efficient Catalysts in the Solventless Plasmon Mediated Oxidation of <i>sec</i>-Phenethyl and Benzyl Alcohol

Surface plasmon excitation of supported gold nanoparticles in the presence of H₂O₂ leads to selective oxidation of <i>sec</i>-phenethyl and benzyl alcohols to the carbonyl products acetophenone and benzaldehyde, respectively, in the absence of additional solvents. Light-emitting diodes are compared with microwave irradiation as excitation sources. Hydrotalcite, ZnO, and Al₂O₃ have been chosen as the solid supports. The overall efficiency of the alcohol oxidation was found to be largely dependent on the nature of the support, with hydrotalcite-derived nanocomposites giving the highest conversions to product, yielding 90% acetophenone after 40 min of LED irradiation. The mechanism for plasmon-mediated alcohol oxidation is believed to involve a significant contribution from the support itself, with adsorption of the alcohol substrate and progression of the oxidation reaction being largely facilitated by the basicity of the support used

Presentation1_2′-19F labelling of ribose in RNAs: a tool to analyse RNA/protein interactions by NMR in physiological conditions.pdf

Protein-RNA interactions are central to numerous cellular processes. In this work, we present an easy and straightforward NMR-based approach to determine the RNA binding site of RNA binding proteins and to evaluate the binding of pairs of proteins to a single-stranded RNA (ssRNA) under physiological conditions, in this case in nuclear extracts. By incorporation of a 19F atom on the ribose of different nucleotides along the ssRNA sequence, we show that, upon addition of an RNA binding protein, the intensity of the 19F NMR signal changes when the 19F atom is located near the protein binding site. Furthermore, we show that the addition of pairs of proteins to a ssRNA containing two 19F atoms at two different locations informs on their concurrent binding or competition. We demonstrate that such studies can be done in a nuclear extract that mimics the physiological environment in which these protein-ssRNA interactions occur. Finally, we demonstrate that a trifluoromethoxy group (-OCF3) incorporated in the 2′ribose position of ssRNA sequences increases the sensitivity of the NMR signal, leading to decreased measurement times, and reduces the issue of RNA degradation in cellular extracts.</p