Magnolol-loaded polydopamine-chitosan coated pH-responsive nanoparticles for alleviation of ulcerative colitis

This study designed and developed a novel three-layer electrostatic, slow-releasing nanoparticle drug delivery system for the treatment of ulcerative colitis. The nanoparticles were composed of layers of zein-based polydopamine, chitosan and cellulose acetate phthalate to form a polyelectrolyte multilayer core−shell nanoparticle structure. The anti-inflammatory natural product magnolol was chosen to be the model drug for the study. The nanoparticles (260.50 ± 23.90 nm) were prepared with layer-by-layer coating and then assessed in vitro and in vivo using a mouse model of ulcerative colitis. The in vitro data confirmed the slow-releasing and pH-dependent characteristics of particles. Quantitative analysis of the in vivo distribution of Mag in mice showed significantly higher concentrations in colonic tissue than in the upper gastrointestinal tract (854.6 ng/g vs 291.5–351.1 ng/g, respectively). Histological and pro-inflammatory cytokine analysis indicated that the nanoparticles had a significant anti-inflammatory effect and were protective against DSS-induced structural damage of the colonic mucosal structure. These results confirm that this nano-delivery system could increase the levels of Mag reaching the colon, resulting in greater efficacy than free Mag in treating UC in this mouse model.