A novel activated NIR-II phototheranostic nanoagent and its application to photothermal therapy

Phototheranostic nanoagent with NIR-II fluorescence imaging and photothermal therapy (PTT) may allow high-quality imaging guided efficient ablation of deep-tissue tumors. Non-specific distribution in vivo may lead to poor imaging results and a risk of damage to normal tissues. However, developing an activable NIR-II nanoagent for photothermal therapy is challenging. Herein, a new polarity-sensitive phototheranostic nanoagent (DC@PEG) is developed for combinational tumor-specific NIR-II fluorescence imaging and photothermal therapy. DC@PEG has a maximum emission exceed 1200 nm at 808 nm excitation. In vivo fluorescence imaging indicated the nanoparticles could accurately distinguish normal tissue (high polarity environment) and tumor tissue (low polarity environment). Furthermore, DC@PEG effectively inhibited the growth of 4T1 tumor under 808 nm laser irradiation with a high photothermal conversion efficiency of 48.1 %. This work provides a promising strategy for development of excellent NIR-II nanoagent with good biocompatibility and deep tissue penetration. This novel nanoagent can served as a robust tool for photothermal therapy of deep tumors.