Insights into Natural Photosensitizer‐Based Nanotherapeutics in Photodynamic Therapy of Cancer

ABSTRACT Photodynamic therapy (PDT) is a minimally invasive cancer treatment that uses photosensitizers (PSs), light, and oxygen to generate cytotoxic reactive oxygen species. Natural product‐derived PSs, including alkaloids, flavonoids, polyphenols, curcuminoids, perylenequinones, phycocyanin, and anthraquinones, offer advantages such as biocompatibility and low toxicity but are limited by poor solubility, stability, and targeting. Nanotherapeutic systems such as organic, inorganic, and carbon‐based nanoparticles, nanogels, hydrogels, lipid carriers, and nanoemulsions address these limitations by enhancing stability, tumor accumulation, and controlled release. These platforms also enable multifunctional approaches, including imaging‐guided PDT, combination therapies, and stimuli‐responsive activation. This review highlights mechanisms, recent advances, and translational challenges of natural PS‐based nanotherapeutics across multiple cancers, emphasizing strategies to improve delivery, selectivity, and therapeutic outcomes for next‐generation PDT.