Biosynthesis of Silver-Based Nanoparticles Using Supernatants of Microbial Cultures for Cultural Heritage Preservation

Abstract

Microbial contamination of Cultural Heritage (CH) materials is one of its most prevalent and impacting preservation issues that can lead to visual, structural, and chemical changes1. Currently, different approaches try to address this issue by employing products and techniques that can lead to structural or chemical alteration of materials2 and pose several environmental risks3. For these reasons, nanotechnological solutions can constitute new greener alternatives. Studies on metalbased nanoparticles (NPs) have described their efficient antimicrobial properties and long-term effects at low concentrations4. However, their stability is highly dependent on surface functionalization, and their chemical synthesis methods may also raise environmental issues. The use of microbial cultures lowers the environmental impact of metal-based NPs’ synthesis and stabilizes them with probable antimicrobial potentiating molecules secreted by these microorganisms5. In this study, we have successfully synthesized metal-based NPs using supernatants of microbial cultures. Their morphological, chemical, and physical characterization using spectrophotometric, x-ray based, and electron microscopy techniques was made, and their antimicrobial activity evaluated against several microorganisms isolated from CH. Results show good antimicrobial potential and stability of the biosynthesized NPs and suggest that the distinct supernatants result in variable NPs properties. Therefore, while further optimization of the synthesis process is necessary, and comprehensive testing using mock-ups and real Cultural Heritage materials is pending, our findings confirm that this approach is a promising alternative to the current traditional biocides.