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

• Biomediated synthesis of Ag nanoparticles with controlled sizes is presented.
• Tobacco mosaic virus (TMV) acts as an efficient sacrificial biomediator.
• Ag particles show high catalytic activity for nitrophenol hydrogenation reaction.
• TMV-mediated Ag nanoparticles have high antibacterial activities against E. coli.

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.

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