Recent advances in photonanomedicines for enhanced cancer photodynamic therapy

Nowadays, photodynamic therapy (PDT) that employs photosensitizers (PSs) to generate cytotoxic species under light irradiation for selective destruction of neoplastic lesions has attracted extensive research attention. Despite the significant progress of PDT, its clinical-translation is still hampered by the insufficiency of three essential elements (light, PSs, and oxygen) at tumor sites. Spurred by the current explosion of nanotechnology, developing photonanomedicines (PNMs) to overcome critical obstacles of conventional PDT has become promising. In this review, we highlight recent research advances in PNMs, which focus on enhanced efficiency of cancer PDT. The design strategies of PNMs are classified into four sections, overcoming the limited light penetration depth, increasing the local PSs concentration, tackling the hypoxic problem, as well as combining with other treatments. Furthermore, the issues and outlook of PNMs for enhanced PDT are also discussed.