ROS-responsive carboxymethyl chitosan nanoparticles loaded with astaxanthin for alleviating oxidative damage in intestinal cells.

The controlled release of antioxidant substances at the intestinal oxidative damage site is crucial for alleviating intestine-related diseases. Herein, the novel ROS-responsive carrier was synthesized through simple amidation reaction between carboxymethyl chitosan (CMC) and methionine (Met), a natural organic compound containing ROS-responsive linkages (thioether). Initially, astaxanthin (AXT) nanoparticles (AXT 2 @CMT) with excellent stability and drug loading capacity (39.68 ± 0.23 μg/mL) were prepared by optimizing various reaction conditions. In the simulated high-concentration ROS environment of the intestine, CMT achieved a transition from hydrophobic groups (thioether) into hydrophilic groups (sulfone), which was conducive to the controlled release of AXT. In vitro cell experiments revealed that AXT 2 @CMT could effectively alleviate the oxidative damage in intestinal epithelioid cell line No. 6 (IEC-6 cell) caused by H 2 O 2. This study achieved a straightforward preparation of ROS-responsive nanocarrier through food ingredients, offering a theoretical foundation for the controlled release of AXT at the intestinal oxidative damage site. • Novel ROS-responsive carrier was synthesized by simple amidation reaction. • ROS-responsive behavior was realized by thioether in methionine. • The thioether in the carrier could be oxidized to sulfone by the ROS in the intestine. • The controlled release of astaxanthin was achieved under a high concentration of ROS. • The nanoparticles could effectively alleviate the oxidative damage in IEC-6 cells. [ABSTRACT FROM AUTHOR]