Laser-Mediated antibacterial effects of Few- and Multi-Layer Ti3C2Tx MXenes

Ti3C2Tx nano-sheets (MXenes) with excellent light-conversion capacity have gained importance in treating infectious diseases due to their limited bacterial resistance. In this study, we exploit this property to design photothermal antibacterial therapy using few- (FX) and multi-layer (MX) Ti3C2Tx nano-sheets. We demonstrate that FX have a higher cytocompatibility and conversion of light to heat, but MX show a better efficacy in inhibiting growth of S. aureus and E. coli due to MXenes' reversible bacteria trapping. For MX (25 mu g/mL), square 37% of E. coli and square 23% of S. aureus cells survived, while the effect was less pronounced for FX with square 72% of E. coli and square 46% of S. aureus viable cells after treatment. After using 100 mu g/mL of MX, square 11% of E. coli and square 46% of S. aureus survived, while FX had only a mild effect on both species. The NIR laser treatment increased the efficacy of both materials: 100 mu g/mL of MX combined with 5 min laser treatment at 5.7 W cm(-2) completely killed both species. For FX, the treatment with 3 W cm(-2) and the highest concentration (100 mu g/mL) induced an effect comparable to MX (87% on E. coli, 95% on S.aureus). The combined NIR MXene treatment causes an irreversible cell death linked to the loss of cell integrity (DNA release quantification and bacteria debris observation).

Automated summary

Ti3C2Tx nano-sheets (MXenes) are used for photothermal antibacterial therapy, with few-layer sheets showing higher cytocompatibility and light-to-heat conversion, while multi-layer sheets are more effective in inhibiting the growth of S. aureus and E. coli due to reversible bacteria trapping. Laser treatment enhances the efficacy of both materials, with multi-layer sheets combined with laser completely killing both species.