Recent advances in the design of organic photothermal agents for cancer treatment: A review

Photothermal therapy (PTT) for cancer treatment has been rapidly advanced in recent years owing to its non-invasive approach and effectiveness. However, its clinical applications are limited by several challenges. Consequently, researchers have focused on improving the targeting capability of Photothermal Agents (PAs), designing activatable PAs, and using near-infrared-II light (NIR-II, 1000–1700 nm) as the excitation source. As the previous reviews on PTT have described nanomaterials and traditional photothermal contrasts based on nanotechnology, this review discusses the recent advances (2018 to 2023) in the rational design of organic PAs for PTT, which could promote the widespread use of these agents in clinical practice. In this review, we describe the PTT capabilities of porphyrin (Por), phthalocyanine (Pc), boron-dipyrromethene (BODIPY), cyanine, croconaine, rhodamine, and squaraine derivatives and conjugated polymers. Other PAs with planar structures and rationally designed based on electronic effects (donor–acceptor (D-A) effect, photoinduced electron transfer (PET), intermolecular non-radiative decay, and AIE luminogens (AIEgens)), NIR-II agents, activatable agents, drug delivery systems, and cell-organelle-targeted agents are also described. Finally, we discuss potential directions for research in this field to promote widespread clinical applications of organic PAs.