An Au NC- and Ag NP-Loaded DNA Microcapsule-Based System for the Detection and Elimination of Staphylococcus aureus

Early detection and deactivation of Staphylococcus aureus (S. aureus) are of great importance to prevent pathogen-induced bacterial infectious diseases. Here, we initially synthesized stimuli-responsive DNA microcapsule coencapsulating gold nanoclusters (Au NCs) and silver nanoparticles (Ag NPs) (Au/Ag/DNA microcapsule) and, using it, developed a sensing platform for the detection and elimination of S. aureus. In this system, Ag NPs were used as inactivators, while Au NCs acted as fluorescence (FL) probes. Single-stranded DNA 1 (S1), single-stranded DNA 2 (S2), and aptamer (Apt) were hybridized on the surface of the microcapsule to form a DNA shell. In the presence of S. aureus, the Apt specifically bound to it, triggering the unlocking of the DNA microcapsule and the release of Au NCs and Ag NPs. The amount of Au NCs, which depends on the concentration of S. aureus, could be monitored by fluorescence (FL) spectroscopy and enable quantitative detection of S. aureus over a linear range of 101-107 CFU/mL. Meanwhile, the released Ag NPs could achieve in situ elimination of S. aureus. This study demonstrated promising application potential in the antibacterial treatment of skin infections and provided valuable insights into the integration of detection and deactivation strategies for S. aureus.