Mechano-assisted synthesis of lignin-based hybrid materials for antimicrobial applications

Lignin and lignin-based materials represent a great opportunity to develop novel materials that combine the antioxidant and antibacterial properties of the polyphenolic matrix with the biological profile of an inorganic phase. We here use a mechano-assisted approach to obtain straightforward isolation of the hybrid materials HMW@ZnO, HMW@Cu₂O, and the mixed-oxide HMW@ZnO_Cu₂O, where HMW (High Molecular Weight) is a Kraft lignin from Pinus taeda . Full material characterization confirmed that mechano-synthesis is an efficient method for smoothly forming products with controlled amounts of Zn, Cu or both, embedded within the Kraft lignin matrix. In vitro testing against four pathogens ( Staphylococcus aureus , Lactococcus garvieae , Escherichia coli , and Aeromonas veronii ) showed that all lignin hybrids exhibited enhanced antimicrobial activity compared to pure reference metal oxides. Crucially, the HMW@ZnO_Cu₂O hybrid demonstrated superior efficacy (lower MBC values) against S. aureus and A. veronii compared to the single-oxide hybrids, suggesting a positive interaction mechanism between the combined metal phases. These findings validate mechano-assisted synthesis as an effective route for developing potent, lignin-based antimicrobials.