Organic conjugated small molecules with donor–acceptor structures: design and application in the phototherapy of tumors

Abstract

Tumor phototherapies including mainly photothermal therapy (PTT) and photodynamic therapy (PDT) have drawn increasing attention due to their various merits of minimal drug resistance, low invasiveness and good spatial–temporal controllability. Photosensitizers play a key role in these processes. Under laser irradiation, tumor cells can be killed by hyperpyrexia or reactive oxygen species produced by photosensitizers. Compared with inorganic photosensitizers and conjugated polymer photosensitizers, organic small-molecule photosensitizers exhibit many valuable advantages, such as excellent biocompatibility, low toxicity, high reproducibility and facile molecular tailoring. In this field, the development of organic conjugated small-molecule photosensitizers that contain donor–acceptor backbones has maintained strong momentum. More and more types of such photosensitizers have been designed for PTT, PDT or their synergistic phototherapy. In this review, we highlight the design strategy adopted for diverse conjugated backbones in organic conjugated small-molecule photosensitizers and give a comprehensive summary of their applications in tumor phototherapy.