Nanometals Templated by Tobacco Mosaic Virus Coat Protein with Enhanced Catalytic Activity

Abstract

Bio-nano hybrid materials feature eco-friendly synthesis, various self-assembly patterns and numerous possibilities of surface functionalization. Owing to these unique advantages, biological scaffolds have been be regarded as green alternatives to fabricate metallic nanomaterials for catalytic applications. In this study, a bulky tobacco mosaic virus coat protein (TMVCP) has been employed as a versatile template to synthesize nanometals (Pd, Pt and Au) in alkaline buffer at room temperature. Protein-functionalized nanoparticles (NPs) with ca. 3 nm in diameter were obtained with uniform size distributions. These materials are green catalytic systems with exceptional performance for small organic molecule transformations in water. Remarkably, while Au NPs showed rapid kinetics in 4-nitrophenol reduction (rate constant with Au NPs: 0.01862 s-1), Pd NPs exhibited superior catalytic activity towards hydrogenation of allyl alcohol (Turnover frequency of Pd NPs: 6382 ± 200 mol product (mol Pd * h)-1) and a set of derivatives. The enhanced catalytic performance is strongly related to the protein ligand. To ascertain the protein structure-function effect on the catalytic performance, an in-depth analysis was performed for the TMVCP-Pd NP system via molecular dynamic (MD) simulations. Our results suggest that due to the moderate interaction between Pd and protein and the steric hindrance of the bulky protein, a large portion of the Pd NP surface remains approachable for the reactant molecules, thus resulting in enhanced reaction rate.