Silver nanocoatings at large length scales: Influence of the AgNPs morphology and capping agents on the coating chemical stability and antimicrobial effect

Abstract

We assessed at multiple length scales (nanometers to millimeters) the nanocoatings of silver nanoparticles (AgNPs) on model SiO2/Si substrates. The coatings from biogenic AgNPs (from yeasts Rhodotorula glutinis and Rhodotorula mucilaginosa) were compared to those formed from "synthetic" AgNPs capped with citrate and sodium dodecyl sulfate (SDS). With computational analysis of large-field (LF) X-ray images of the whole substrates (5 × 5 mm), we were able to assess the coatings homogeneity, relative amount of AgNPs, and their distribution as agglomerates. Surprisingly, by analyzing more than 100,000 elements (nanoparticles and agglomerates) in each sample, it was observed that the mentioned features have little dependence on the AgNPs morphology and capping agents. All silver nanocoatings resisted when immersed in phosphate-buffered saline medium by forming agglomerates of up to 10 μm2. However, coatings formed with synthetic AgNPs (capped with citrate and SDS) led to a higher antimicrobial efficiency against Staphylococcus aureus.