All-in-one inorganic nanoagents for near-infrared-II photothermal-based cancer theranostics

Theranostic nanoplatforms combining various diagnostic and therapeutic units together have attracted increasing attention over the past few decades. Owing to the merits of non-invasiveness, spatiotemporal controllability, high treatment efficacy and low normal-tissue damage, photothermal therapy (PTT) especially near-infrared-II (NIR-II, 1000–1700 nm) light-triggered PTT becomes one of the most popular therapeutic modalities. Interestingly, photothermal agents (PTAs) used for PTT often have an intrinsic photoacoustic (PA) imaging function, which means that PTAs alone can serve as all-in-one theranostic nanoplatforms. With the rapid development of nanomedicine, a single photothermal agent can be endowed with desirable photothermal conversion efficiency (PCE) in the NIR-II biowindow as well as possessing diverse treatment capabilities. This review summarizes the most recent advances of inorganic PTAs for imaging-guided NIR-II PTT, PTT/photodynamic therapy (PDT), PTT/chemodynamic therapy (CDT), PTT/radiotherapy (RT), PTT/sonodynamic therapy (SDT), PTT/PDT/CDT and PTT/SDT/immunotherapy. Potential obstacles and perspectives for future research and clinical translation of such novel nanotheranostics are also discussed.