Silver nanoparticles synthesized and coated with pectin: An ideal compromise for anti-bacterial and anti-biofilm action combined with wound-healing properties

Abstract

The synthesis of Ag nanoparticles from Ag⁺ has been investigated, with pectin acting both as reductant and coating.∼100% Ag⁺ to Ag(0) one-pot conversion was obtained, yielding p-AgNP, i.e. an aqueous solution of pectin-coated spherical Ag nanoparticles (d=8.0±2.6nm), with a<1ppm concentration of free Ag⁺ cation. Despite the low free Ag⁺ concentration and low Ag⁺ release with time, the nature of the coating allows p-AgNP to exert excellent antibacterial and antibiofilm actions, comparable to those of ionic silver, tested on E. coli (Gram-) and S. epidermidis (Gram+) both on planctonic cells and on pre- and post-biofilm formation conditions. Moreover, p-AgNP were tested on fibroblasts: not only p-AgNP were found to be cytocompatible but also revealed capable of promoting fibroblasts proliferation and to be effective for wound healing on model cultures. The antibacterial activity and the wound healing ability of silver nanoparticles are two apparently irreconcilable properties, as the former usually requires a high sustained Ag⁺ release while the latter requires low Ag⁺ concentration. p-AgNP represents an excellent compromise between opposite requirements, candidating as an efficient medication for repairing wounds and/or to treat vulnerable surgical site tissues, including the pre-treatment of implants as an effective prophylaxis in implant surgery.

Keywords: Anti-infective biomaterials; Biofilm; Silver cation; Silver nanoparticles; Wound healing.