Donor strategy for promoting nonradiative decay to achieve an efficient photothermal therapy for treating cancer

Photothermal therapy (PTT) is emerging as an effective treatment for superficial carcinoma. A key challenge to the effectiveness of PTT is to develop photosensitizers with high photothermal conversion efficiency. Aiming to address this challenge, we develop a series of multi-arylpyrrole derivatives with different donors that contain different multi-rotor structures to explore highly efficient PTT photosensitizers. Among these multi-arylpyrrole derivatives, MAP4-FE nanoparticles with a small size of their donor groups and better-donating ability exhibit a high photothermal conversion efficiency (up to 72%) when they are encapsulated by an amphiphilic polymer. As a result, the MAP4-FE nanoparticles have shown satisfactory PTT effects on in vivo tumor eradication under the guidance of photoacoustic signals. The findings of this study provide significant insights for the development of high-efficiency PTT photosensitizers for cancer treatment by making full use of the nonradiative decay of small size donors as rotors.