Breaking Barriers in Biofilm Control: ZnS and Au@ZnS Core-Shell Nanoconjugates Target ESKAPE Pathogens

The escalating prevalence of antibiotic-resistant infections and implant-related complications caused by biofilm-forming pathogens from the ESKAPE group, as identified by the World Health Organization (WHO), underscores the urgent need for innovative anti-biofilm strategies. Their occurrence on medical implants & prosthetic devices, as well as nosocomial infections in co-morbid patients, has become a global concern in the healthcare sector. In response, we investigated the efficacy of as-synthesized ZnS quantum dots (ZnS QD) and novel Au@ZnS nanoconjugates (Au@ZnS NC) against a spectrum of ESKAPE pathogens. The present study aimed to elucidate their antibacterial and anti-biofilm efficacy, focusing on Acinetobacter baumannii, Enterobacter cloacae, Staphylococcus epidermidis, Enterococcus faecium, Proteus mirabilis, Pseudomonas aeruginosa, Enterococcus faecalis, Staphylococcus aureus and Enterobacter aerogenes pathogens. The novel synthesis and application of ZnS QD and Au@ZnS core-shell NC demonstrate exceptional anti-biofilm efficacy, stability, and solubility in aqueous environments. Utilizing minimum inhibitory concentration (MIC) assays, tube dilution, and biofilm formation assay, we noticed a significant reduction in biofilm formation and extracellular polymeric substances (EPS) production upon treatment with Au@ZnS NC, even at low concentrations. Further investigations, including cell permeability assay, reactive oxygen species analysis, and comet analysis, demonstrated that the Au@ZnS NC induced oxidative stress, destabilizing cell structure, macromolecule destruction, and DNA strand breakage. Notably, Au@ZnS nanoconjugates effectively inhibited biofilm formation within 24 hours across all tested strains, outperforming ZnS quantum dots. This research highlights the potential of Au@ZnS nanoconjugates to revolutionize infection control on medical devices and implants, offering a promising solution to the global healthcare challenge posed by biofilm-forming pathogens as we also observed minimal bacterial colonization on Au@ZnS treated urinary catheters.