Chapter 12 - Tannic acid modification of metal nanoparticles: possibility for new antiviral applications

Abstract

Tannins are phenol derivatives naturally synthesized by plants as metabolic products. For centuries tannins have been used in medicine as agents supporting wound healing, due to their antiinflammatory and antimicrobial properties. Tannic acid is the most common and principal hydrolysable tannin. Here, we describe the method for synthesis of silver or gold copper/silver nanoparticles by chemical reduction method using tannic acid. This method allows for precise shape and size control of metallic nanoparticles having surface modified by tannic acid to increase attachment, antimicrobial and antiinflammatory properties. The interaction between nanoparticles and viruses is attracting great interest due to the need for new antivirals. We demonstrated that tannic acid modified silver nanoparticles are capable of reducing herpes simplex type 2 (HSV-2) infectivity both in vitro and in vivo. The antiviral activity of tannic acid modified silver and silver/copper nanoparticles was size-related, required direct interaction and blocked virus attachment, penetration and further spread. All tested tannic acid modified AgNPs and Ag/CuNPs reduced both infection and inflammatory reaction in the mouse model of HSV infection. Therefore, tannic acid modified silver and silver copper alloy nanoparticles consist good candidates for microbicides used in treatment of infections with enveloped viruses, such as herpes viruses.