Titanium carbide MXene-based hybrid hydrogel for chemo-photothermal combinational treatment of localized bacterial infection

With the increased emergence and threat of multi-drug resistant microorganisms, MXenes have become not only an emerging class of two-dimensional functional nanomaterials, but also potential nanomedicines (i.e., antimicrobial agents) that deserve further exploration. Very recently, Ti3C2 MXene was observed to offer a unique membrane-disruption effect and superior light-to-heat conversion efficiency, but its antibacterial property remains unsatisfactory due to poor MXene-bacteria interactions, low photothermal therapy efficiency, and occurrence of bacterial rebound in vivo. Herein, the cationic antibiotic ciprofloxacin (Cip) is combined with Ti3C2 MXene, and a hybrid hydrogel was constructed by incorporating Cip-Ti3C2 nanocomposites into the network structure of a Cip-loaded hydrogels to effectively trap and kill bacteria. We found that the Cip-Ti3C2 nanocomposites achieved an impressive in vitro bactericidal efficiency of >99.99999% (7.03 log10) for the inhibition of methicillin-resistant Staphylococcus aureus (MRSA) by combining chemotherapy with photothermal therapy. In an MRSA-induced murine abscess model, the hybrid hydrogel simultaneously achieved high-efficiency sterilization and long-term inhibition effects, avoiding the rebound of bacteria after photothermal therapy, and thus maximized the in vivo therapeutic efficacy of Ti3C2 MXene-based systems. Overall, this work provides a strategy for efficiently combating localized bacterial infection by rationally designing MXene-based hybrid hydrogels. Two-dimensional Ti3C2 MXene was recently regarded as a promising functional nanomaterial, however, its antibacterial applications are limited by the poor MXene-bacteria interactions, low photothermal therapy efficiency, and the occurrence of bacterial rebound in vivo. This work aims to construct a Ti3C2 MXene-based hybrid hydrogel for chemo-photothermal therapy and enhance the antimicrobial performance via a combination of the high-efficiency sterilization of ciprofloxacin-Ti3C2 nanocomposites with the long-term inhibition effect of ciprofloxacin hydrogel. The present study provides an example of efficient MXene-based antimicrobials to treat localized bacterial infection such as methicillin-resistant Staphylococcus aureus (MRSA)-induced skin abscess.