NIR-II-absorbing conjugated polymer-based theranostic agent for NIR-II fluorescence imaging-guided photothermal therapy acting synergistically with tumor microenvironment-responsive nitric oxide therapy

Despite tremendous advances in gas therapy, there are major concerns about the inevitable concentration of toxicity and the ability to perform real-time tracking of drug delivery. Second near-infrared (NIR-II) window absorbing nanoplatforms hold great promise for precision medicine because of their excellent tissue penetration of light and non-invasive nature. In this study, we engineered an NIR-II laser-activated theranostic agent (named [email protected]) that was composed of amphiphilic polymers (Pluronic F127, with polyethylene glycol, PEG, moieties) coated with an NIR-II-absorbing conjugated polymer (PTTBBT, CP) and nitric oxide (NO) donor (benzofuroxan, bF), which served as an NIR-II photothermal inducer and NO nanogenerator. Under deep tissue penetration of NIR-II laser irradiation, [email protected] was found to possess fluorescence imaging ability to accurately identify tumor and excellent photothermal effect. Moreover, [email protected] could generate NO via glutathione activation in the tumor microenvironment in a controllable manner. This NIR-II-absorbing polymer for high-contrast NIR-II fluorescence imaging-guided precision photothermal therapy achieved synergistic effects with NO therapy, as evidenced by pronounced tumor therapeutic efficacy and few side effects. This nanotheranostic agent is a highly promising candidate for high-contrast NIR-II imaging-guided precision photothermal therapy combined with gas therapy against cancer.