Triplex DNA-Silver Nanoclusters: Tunable Fluorescence and Light-Enhanced Antibacterial Activity

Silver nanoclusters (AgNCs) hold great potential for biosensing and antibacterial applications. By leveraging the structural flexibility of triplex or triple-stranded deoxyribonucleic acid (tsDNA), tsDNA-AgNCs with tunable fluorescence and enhanced antibacterial activity are constructed. The two cytosine (C)-rich termini sequences in the long DNA strand serve as the template for synthesizing AgNCs, and the close proximity of the guanine (G)-rich sequence to the AgNCs and that between the two nanoclusters mediated by triplex DNA formation significantly enhance the fluorescence. The fluorescence emission of the tsDNA-AgNCs can be tuned from red to green by varying the number of cytosines in the cluster-nucleation sequence on the DNA template. The antibacterial activity of the tsDNA-AgNCs is evaluated using Escherichia coli and Staphylococcus aureus, and the blue light irradiation can further enhance the antibacterial capability of tsDNA-AgNCs through increased reactive oxygen species (ROS) generation and Ag⁺ release. The tsDNA-stabilized AgNCs serve as a promising platform for stronger fluorescence output and antibacterial treatment.