Colloidal synthesis of gold and silver metal nanocrystals for studies of their antiviral activity

The ability to control the size of metal nanocrystals (NCs) is significant for many areas of science and modern technologies including catalysis, plasmonics, electronics, biomedicine and others. Previous studies show that Au and Ag NCs in this size range have potential as antiviral agents provided that they can be synthesized in a controlled way in the size range <100 nm. Herein, we describe a simple and efficient synthetic method for preparation of aqueous gold and silver NCs with well-defined sizes from tetrachloroauric acid (HAuCl₄) and silver nitrate (AgNO₃), respectively. The control over the size of the NCs is achieved via adjustment of concentrations of the reducing agents (tannic acid and sodium citrate), amounts of gold and silver precursors, temperature and pH. This resulting NCs, surface stabilized with surfactants are stable with respect to precipitation in aqueous solution. Using UV-vis spectroscopy and previously developed calibration curves we determined that the prepared NCs vary in sizes from 4 to 20 nm, optimal for studies of antiviral activity. (authors)