Antagonistic antimicrobial effect observed in silver nanoparticles stabilized with lysozyme

REY, VALENTINA; ESPECHE TURBAY, M. BEATRIZ; SOSA, MARCELO; DORADO, RITA D.; BORSARELLI, CLAUDIO D.

San Luis, Argentina

Congreso; XLVIII Reunión Anual de la Sociedad Argentina de Biofísica; 2019

Silver nanoparticles (AgNPs) are well recognized new generation of antimicrobials, as well as lysozyme (14 kDa) is a protein present in body fluids with membrane lytic activity, acting as a natural antimicrobial. Therefore, could be expected that combination of both types of antimicrobial can result in a synergistic effect, particularly for the treatment of multi-strains or pan-resistant strains. Recently, we characterized the photoreductive synthesis of silver nanoparticles (NPs) stabilized with lysozyme (AgNP@LZ). Surprisingly, AgNP@LZ lacks antimicrobial activity on grampositive and gramnegative strains, being a biological example of "antagonistic effect". In order to understand the interactions that control the functionality of this bionanocomposite, we have studied the structural modifications of the stabilizing protein, the type of specific interactions between the metal surface and the peptide residues, and also by comparing the antimicrobial activity of others AgNPs stabilized with ion citrate (CIT) or serum bovine albumin (BSA) by the effect of adding native LZ. Results show that in the AgNP@LZ the protein strongly interacts with the metal surface, forming a hard crown on the nanoparticle surface. As a result, this hard corona efficiently binds the silver cation Ag+ (which believed the antimicrobial agent) hindering its diffusion into the medium avoiding microbicide activity.Hence, this study remarks the relevance of a complete knowledge of the specific interactions between components in a nanocomposite system for the design of nanobiomaterials with suitable antimicrobial activity.