Viral templates for gold nanoparticle synthesis

Abstract

Viruses present a confined environment and unique protein surface topology (i.e. polarity, residue charge, and surface relief) for nanoparticle synthesis and are amenable to molecular biology manipulations. Consequently, we have examined the cowpea chlorotic mottle viruses of unmodified SubE (yeast), (HRE)-SubE engineered with interior HRE peptide epitopes (AHHAHHAAD), and wild-type as viral templates for the potentiated reduction and symmetry directed synthesis of gold nanoparticles. In the first approach, the viral capsid actively potentiated the reduction of AuCl₄⁻ by electron transfer from surface tyrosine residues resulting in a gold nanoparticle decorated viral surface. Viral reduction appeared to be selective for gold as a collection of metal precursor substrates of Ag⁺, Pt⁴⁺, Pd⁴⁺, and an insoluble Au^I complex were not reduced to zero-valent nanoclusters by virus. Alternatively, the viral capsid provided a template for the symmetry directed synthesis of Au⁰ nanoparticles from a non-reducible gold precursor.