Singlet Oxygen “Afterglow” Therapy with NIR‐II Fluorescent Molecules

• DOI: 10.1002/adma.202103627
• Publication Date: 2021-09-13T09:53:17Z
• Authors: Jianhua Zou; Ling Li; Jianwei Zhu; Xiangchun Li; Zhen Yang; Wei Huang; Xiaoyuan Chen
• Keywords: Singlet Oxygen; 01 natural sciences; 0104 chemical sciences

AbstractImproving singlet oxygen (1O2) lifespan by fractionated delivery in dark and hypoxic conditions is a better way to achieve enhanced phototherapeutic efficacy. Herein, three boron dipyrromethene (BODIPY) dyes are synthesized to demonstrate that anthracence‐functionalized BODIPY, namely ABDPTPA is an efficient heavy‐atom‐free photosensitizer for the reversible capture and release of 1O2. The spin–orbit charge‐transfer intersystem crossing of ABDPTPA promises a high 1O2 quantum yield of 60% in dichloromethane. Under light irradiation, the anthracene group reacts with 1O2 to produce endoperoxide. Interestingly, after termination of irradiation, the endoperoxide undergoes thermal cycloreversion to produce 1O2, and regenerates the anthracene module to achieve 1O2 “afterglow,” which results in a prolonged half lifetime of 1O2 for 9.2 min. In vitro cytotoxicity assays indicate that ABDPTPA nanoparticles have a low half‐maximal inhibitory concentration (IC50) of 3.6 µg mL−1 on U87MG cells. Further, the results of near‐infrared‐II fluorescence‐imaging‐guided phototherapy indicate that ABDPTPA nanoparticles can inhibit tumor proliferation even at a low dose (200 µg mL−1, 100 µL) without any side effects. Therefore, the study provides a generalized 1O2 “afterglow” strategy to enhance phototheranostics for complete tumor regression.