Visible light-triggered NIR ratiometric fluorescent metal-free CO-releasing molecule for self-monitoring of CO delivery and effective cancer therapy

Cancer is a serious global health issue, and exploring effective treatment methods is of great significance for cancer prevention and control. Carbon monoxide (CO), as an important gas signaling molecule in the life system, has been proven to have good anti-cancer effects. However, how to controllably, safely, and effectively deliver CO to the tumor site for clinical treatment remains a challenge. Herein, a new metal-free CO-releasing molecule COR-XAC was developed for controlling CO release and cancer therapy. COR-XAC is based on the hybrid of 3-hydroxyl flavone and oxanthracene fluorophores, showing visible light-controlled CO-releasing properties and near-infrared (NIR) ratiometric fluorescence changes at 690 and 760 nm. COR-XAC shows low cytotoxicity and can be successfully applied to release CO in cells and tumors, and the CO-releasing and delivery process could be monitored by its own NIR ratiometric fluorescence changes. More importantly, the anti-cancer performance of COR-XAC was evaluated in 4T1 tumor mice, and it was found that COR-XAC plus light illumination showed excellent tumor inhibition effect, which provided a promising new effective method for cancer treatment.