Lignin-Derived Gold–Titanium Dioxide Nanophotocomposites as Potent Photoactivatable Probes for Microbial Inactivation

The overuse of antibiotics has accelerated antibiotic resistance, and it is a significant global threat to public health. To combat the rising threat of drug-resistant microbes, antimicrobial photodynamic therapy (APDT) has emerged as a promising alternative therapeutic strategy. This study focuses on the synthesis of eco-friendly lignin-derived gold-titanium dioxide nanophotocomposites (L@Au-TiO₂ NCs). Lignin was utilized as a sustainable precursor for the synthesis of L@Au-TiO₂ NCs. The gold and TiO₂ nanoparticles possess inherent photodynamic properties, and thus the developed L@Au-TiO₂ NCs exhibit enhanced antimicrobial efficacy due to the synergistic combination of their attributes. The antimicrobial potential of the L@Au-TiO₂ NCs was evaluated against various microbial strains (<i>Escherichia coli</i>, <i>Bacillus megaterium</i>, and <i>Candida tropicalis</i>) under dark and green light conditions. The outcome of this study highlights the promising potential of L@Au-TiO₂ NCs for photodynamic antimicrobial applications. The L@Au-TiO₂ nanophotocomposites could be explored in the fields of medicine and nanotechnology to introduce innovative ideas into the biomedical field.