Biosynthesis of silver-based nanoparticles: Critical assessment of antimicrobial assays and diffusion kinetics analysis

Abstract

Synthesis and application of nanoparticles (NPs) have shown promising results in various scientific fields due to their differentiating properties. However, current nanoparticle synthesis methods present environmental challenges. In this study biosynthesized silver nanoparticles (AgNPs) were produced from microbial culture supernatants as an alternative to traditional routes for controlling biodeteriogenic microorganisms in cultural heritage materials. The particles strongly inhibited cultural heritage colonizing bacteria and fungi, with minimum inhibitory concentrations ranging from 3 to 28 ppm. Kinetic analysis of disc diffusion assays revealed that inhibition zones correlate directly with silver ion release rates, rather than nanoparticle diffusion in agar. This led to a proposition of a simplified mechanistic model of Ag-based NPs behavior in disc diffusion assay. These findings carry broad implications - not only for the conservation of Cultural Heritage but also for diverse sectors, particularly human health - where accurate assessment of antimicrobial efficacy is paramount. To ensure accurate assessments, alternative methods should be standardized.