Microenvironment responsive pod-structured astaxanthin nanocarrier for ameliorating inflammatory bowel disease

Anti-inflammatory drugs targeting inflammatory bowel disease (IBD) have attracted considerable attention but still face low therapeutic outcomes and frequent side effects. Astaxanthin (ATX), a natural ketone, possesses potent antioxidant and anti-inflammatory properties. However, it faces problems such as poor water solubility, photothermal instability, and low bioavailability. Here, we employed a supramolecular encapsulation strategy to create a nanoscale oral delivery system for ATX (referred to as FC-ATX NPs) by coupling fucoidan (FUC) with chitosan oligosaccharides (COS). The obtained FC-ATX NPs exhibited a particular "bean pod" structure with uniform size, good encapsulation efficiency, excellent physical and chemical stability, pH-triggered intestinal targeted slow-release properties, and potent antioxidant capacity. In vitro cell culture experiments showed that FC-ATX NPs promoted cellular uptake and scavenged excessive intracellular reactive oxygen species (ROS). In mouse models of colitis, FC-ATX NPs enhanced the drug absorption of intestinal epithelial cells and effectively accumulated at the site of inflammation. This work provides an efficient approach to enhance the bioavailability of ATX and has excellent application potential as an oral targeted delivery system for colitis therapy.