Photopolymerized antimicrobial hydrogels based on thiol-functionalized MXenes and in-situ generated silver nanoparticles.

Here, we report photopolymerized composite hydrogels integrating thiol-functionalized MXene nanosheets with in situ generated silver nanoparticles (AgNPs) to obtain structurally reinforced antimicrobial films. Thiol functionalities were covalently grafted onto the MXene surface to provide a sulfur-containing interfacial environment that may influence dispersion, local Ag-species coordination, and nanoparticle organization while strengthening interfacial interactions within the hydrogel matrix. The hydrogels were fabricated by UV-initiated free-radical polymerization of N-vinyl pyrrolidone (NVP), hydroxyethyl acrylamide (HEAA), and triethylene glycol divinyl ether (DVE) (as crosslinker) in a preformed polymer solution containing poly(vinyl alcohol) (PVA) and hydroxyethyl cellulose (HEC) using a biocompatible photoinitiator. Ag-containing nanoparticles were generated in situ through reduction of AgNO3 by photogenerated radicals and reducing species associated with HEC. Comprehensive physicochemical characterization (SEM-EDX, TEM, FT-IR, XRD, XPS, swelling, gel fraction, and mechanical testing) confirmed formation of a mechanically robust hydrogel network containing incorporated MXene nanosheets and Ag-containing nanodomains. Time-kill assays against Staphylococcus aureus and Escherichia coli demonstrated rapid antibacterial activity over the 24 h test period, with formulation- and strain-dependent responses. SEM observations of bacteria recovered after exposure to Ag-containing hydrogels revealed morphological changes consistent with bacterial-envelope damage. The S0-MXene-SH-Ag formulation exhibited non-cytotoxic extract responses and a borderline, statistically significant reduction in fibroblast metabolic activity under direct-contact conditions. Importantly, Ag-containing films retained functional antibacterial activity after one year of dry storage under ambient conditions, supporting their shelf-storage potential. The combined TEM, ICP-MS, antibacterial assay, and bacterial-SEM results suggest that localized interfacial organization of Ag-containing species contributes significantly to antibacterial performance. Thus, this study introduces the MXene-SH-Ag "fortress" concept, in which Ag-containing nanodomains localized at the MXene-SH interface act as highly effective antibacterial microenvironments, establishing a promising materials platform for antimicrobial wound-contact applications while identifying in vivo wound-healing evaluation as a necessary next step toward clinical translation.