A pH and glutathione-responsive carbon monoxide-driven nano-herb delivery system for enhanced immunotherapy in colorectal cancer.

Dihydroartemisinin (DHA), a compound extracted from the herbal medicine Artemisia annua, has shown promise as a clinical treatment strategy for colorectal cancer. However, its clinical use is hindered by its low water solubility and bioavailability. A pH/glutathione (GSH) dual-responsive nano-herb delivery system (PMDC NPs) has been developed for the targeted delivery of DHA, accompanied by abundant carbon monoxide (CO) release. Due to the passive enhanced permeability and retention (EPR) effect and active targeting mediated by pHCT74 peptide binding to overexpressed α-enolase on colorectal cancer cells, the pHCT74/MOF-5@DHA&CORM-401 nanoparticles (PMDC NPs) exhibited specific targeting capacity against colorectal cancer cells. Once reaching the tumor site, the pH/GSH dual-responsive behavior of metal-organic framework-5 (MOF-5) enabled the rapid release of cargo, including DHA and CORM-401, in the acidic tumor microenvironment. Subsequently, DHA stimulated CORM-401 to release CO, which facilitated ROS-induced ferroptosis and apoptosis, leading to immunogenic cell death (ICD) and a sustained antitumor response through the release of tumor-associated antigens (TAAs) and damage-associated molecular patterns (DAMPs). Overall, PMDC NPs enhanced the bioavailability of DHA and exhibited outstanding therapeutic effectiveness both in vitro and in vivo, indicating their potential as a promising and feasible alternative for synergistic treatment with immunotherapy and gas therapy in the clinical management of colorectal cancer.