Oral colon-targeted mucoadhesive micelles with enzyme-responsive controlled release of curcumin for ulcerative colitis therapy

Although multitudinous nanoscale drug-delivery systems (DDSs) have been recommended to improve anti-ulcerative colitis (UC) outcomes, to enhance the mucoadhesion of nanosystems on the colon and specifically release the loaded drugs in response to the colon micro-environment would be critical factors. The application of curcumin (Cur), an acknowledged anti-UC phytochemical compound, for UC therapy requires more efficient nano-carriers to improve its therapeutic outcome. Herein, we developed the colon-targeted nano-micelles with mucoadhesive effect and Azo reductase-triggered drug release profiles for Cur delivery in UC treatment. Specifically, the amphiphilic block polymer containing the Azo-reductase sensitive linkage (PEG-Azo-PLGA), and catechol-modified TPGS (Cat-TPGS) were synthesized respectively. Based on the self-assembly of the mixed polymers, Cur-micelles (142.7 ± 1.7 nm of average size, 72.36% ± 1.54% of DEE) were obtained. Interestingly, the Cur-micelles exhibited the Azo-reductase sensitive particle dissociation and drug release, the enhanced cellular uptake and the prolonged retention on colonic mucosa, mediated by the strong mucoadhesion of catechol structure. Ultimately, Cur-micelles significantly mitigated colitis symptoms and accelerated colitis repair in DSS-treated mice by regulating the intestinal flora and the levels of pro-inflammatory factors (MPO, IL-6, IL-1β, and TNF-α) related to TLR4/MyD88/NF-κB signaling pathway. This work provides an effective drug delivery strategy for anti-UC drugs by oral administration.