Multifunctional nanocomposites integrated green synthesized amphiphilic chitosan/thyme extract/nanosilver for antimicrobial and anti-biofilm applications

Background: Bacterial biofilms pose a significant challenge in various industries, including healthcare and food production, as they can lead to persistent infections, antibiotic resistance, and contamination. Targeted antimicrobial therapies hold great potential for mitigating the detrimental effects of biofilms. Methods: New amphiphilic chitosans (ACSs) were prepared and used in combination with thyme extract (TE) as synergistic reducing and stabilizing agents in the preparation of biofunctionalized nanosilver (amphiphilic chitosans-TE-nanosilver, ACSs-TE-Ag) for antibacterial and anti-biofilm applications. Results: ACSs-TE-Ag nanocomposites can synergistically inhibt bacterial proliferation and biofilm formation. ACS2-TE-Ag was the most effective antibacterial agent against E. coli and S. aureus, with MIC values of 0.63 and 1.14 mu g/mL, respectively. SEM analysis of the treated bacterial cells showed that ACSs-TE-Ag's greater activity is due to their capacity to rupture the bacterial cell membrane, causing intracellular content leaking and cell death. ACSs-TE-Ag can prevent biofilms by inhibiting bacterial cells from adhering to coated surfaces and killing cells in submerged cultures or biofilms. Conclusions: The ACSs-TE-Ag nanocomposites exhibit strong bactericidal impacts, disrupt biofilm formation, inhibits bacterial adhesion, and effectively kill bacterial cells within the biofilm matrix. Furthermore, its biocompatibility and low cytotoxicity make it a potential candidate for various biomedical applications.