A biofabrication approach for controlled synthesis of silver nanoparticles with high catalytic and antibacterial activities

We report simple, facile and size-controllable synthesis of uniform Ag nanoparticles with tobacco mosaic virus (TMV) as a biomediator in the absence of external reducing agents. UV-vis and TEM analysis show that Ag nanoparticles with average diameter of 2, 4 and 9 nm were obtained by simply tuning the ratio of TMV/Ag(NH3)(2)(+). The Ag formation in the presence of TMV showed autocatalytic growth followed by coalescence. The as-prepared TMV-mediated Ag nanoparticles show substantially higher catalytic and antibacterial activities than previous results. For the 4-nitrophenol hydrogenation reaction, the rate constants per surface area for 2 and 9 nm Ag nanoparticles were determined to be 0.64 and 1.2 L m(-2) s(-1) respectively. Both Kirby-Bauer disk diffusion test and tube culture results demonstrate high antibacterial activity of TMV-mediated Ag particles against Escherichia coli, with minimal inhibition concentration (MIC) of 2.3 and 2.5 ppm for 2 and 9 nm Ag nanoparticles respectively. We expect that our biomediated Ag synthesis approach can be readily extended to other biomaterials and metal nanoparticle systems. (C) 2013 Elsevier B.V. All rights reserved.