A self‐regulated phototheranostic nanosystem with single wavelength‐triggered energy switching and oxygen supply for multimodal synergistic therapy of bacterial biofilm infections.

The exploration of antibiotic‐independent phototherapy strategies for the treatment of bacterial biofilm infections has gained significant attention. However, efficient eradication of bacterial biofilms remains a challenge. Herein, a self‐regulated phototheranostic nanosystem with single wavelength‐triggered photothermal therapy (PTT)/photodynamic therapy (PDT) transformation and oxygen supply for multimodal synergistic therapy of bacterial biofilm infections is presented. This approach combines a eutectic mixture of natural phase‐change materials (PCMs) and an aggregation‐induced emission (AIE) phototheranostic agent TPA‐ICN to form colloidally stable nanopartcicles (i.e. AIE@PCM NPs). The reversible solid−liquid phase transition of PCMs facilitates the adaptive regulation of the aggregation states of TPA‐ICN, enabling a switch between the energy dissipation pathways for enhanced PDT in solid PCMs or enhanced PTT in liquid PCMs. Additionally, oxygen‐carrying thermoresponsive nanoparticles are also introduced to alleviate the hypoxic microenvironment of biofilms by releasing oxygen upon heating by AIE@PCM NPs with enhanced PTT. The nanosystem exhibits outstanding therapeutic efficacy against bacterial biofilms both in vitro and in vivo, with an antibacterial efficiency of 99.99%. This study utilizes a self‐regulated theranostic nanoplatform with adaptive PTT/PDT transformation via the phase transition of PCMs and heat‐triggered oxygen release, holding great promise in the safe and efficient treatment of bacterial biofilm infections. [ABSTRACT FROM AUTHOR]