Mn-doped ZnS quantum dots@dendritic mesoporous silica phosphorescent nanocomposites for antimicrobial susceptibility testing

Abstract

The excessive use of antibiotics has accelerated the rise of antimicrobial resistance (AMR), and rapid antimicrobial susceptibility testing (AST) is very important for the early detection, early prevention and treatment of AMR. On this basis, we combined manganese-doped zinc sulfide quantum dots (Mn-ZnS QDs) with aminated dendritic mesoporous silica nanoparticles (DMSNs-NH₂) to prepare Mn-ZnS QDs@DMSNs-NH₂ room-temperature phosphorescent (RTP) nanocomposites·H₂O₂ can quench the RTP of Mn-ZnS QDs@DMSNs-NH₂ nanocomposites, while catalase-positive bacteria can cause the hydrolysis of H₂O₂. Hence, RTP detection of different antibiotic tolerance for Staphylococcus aureus (S. aureus) and methicillin-resistant Staphylococcus aureus (MRSA) was achieved. This sensing system can achieve rapid bacterial detection and AST through the difference in RTP intensity. Experimental results demonstrated that the linear detection range for bacteria is 0 × 10⁵-64 × 10⁵ CFU·mL⁻¹, with a limit of detection (LOD) of 1 × 10⁵ CFU·mL⁻¹ for MRSA and 0.7 × 10⁵ CFU·mL⁻¹ for S. aureus. The pore confinement effect of DMSNs-NH₂ can induce the aggregation of Mn-ZnS QDs, which strengthens the RTP of Mn-ZnS QDs@DMSNs-NH₂ nanocomposites and improves the sensitivity of RTP detection. This method is not only free from sample background fluorescence interference, but also shortens the AST time (less than 90 min), making antibacterial treatment more time-saving and efficient and reducing patient pains. This nanosensor provides a new strategy for rapid clinical bacterial detection and effective assessment of antimicrobial susceptibility.