Smart Responsive Quercetin-Conjugated Glycol Chitosan Prodrug Micelles for Treatment of Inflammatory Bowel Diseases.

The incidence and progression of inflammatory bowel disease are closely related to oxidative stress caused by excessive production of reactive oxygen species (ROS). To develop an efficacious and safe nanotherapy against inflammatory bowel diseases (IBD), we designed a novel pH/ROS dual-responsive prodrug micelle GC-B-Que as an inflammatory-targeted drug, which was comprised by active quercetin (Que) covalently linked to biocompatible glycol chitosan (GC) by aryl boronic ester as a responsive linker. The optimized micelles exhibited well-controlled physiochemical properties and stability in a physiological environment. Time-dependent NMR spectra traced the changes in the polymer structure in the presence of H2O2, confirming the release of the drug. The in vitro drug release studies indicated a low release rate (<20 wt %) in physiological conditions, but nearly complete release (>95 wt % after 72 h incubation) in a pH 5.8 medium containing 10 µM H2O2, exhibiting a pH/ROS dual-responsive property and sustained release behavior. Importantly, the negligible drug release in a simulated gastric environment in 1 h allowed us to perform intragastric administration, which has potential to achieve the oral delivery by mature enteric-coating modification in future. Further in vivo activities and biodistribution experiments found that the GC-B-Que micelles tended to accumulate in intestinal inflammation sites and showed better therapeutic efficacy than the free drugs (quercetin and mesalazine) in a colitis mice model. Typical inflammatory cytokines including TNF-α, IL-6, and iNOS were significantly suppressed by GC-B-Que micelle treatment. Our work promoted inflammatory-targeted delivery and intestinal drug accumulation for active single drug quercetin and improved the therapeutic effect of IBD. The current study also provided an alternative strategy for designing a smart responsive nanocarrier for a catechol-based drug to better achieve the target drug delivery.

Reactive oxygen species-responsive amino acid-based polymeric nanovehicles for tumor-selective anticancer drug delivery.

Stimuli-triggered drug delivery systems have been recognized as a crucial strategy to achieve on-demand drug release at the tumor for improving therapeutic efficacy. In this work, novel biocompatible and biodegradable reactive oxygen species (ROS)-responsive amino acid- based polymeric micelles were developed for tumor-specific drug release triggered by high ROS levels in cancer cells, which were composed of amphiphilic poly(aspartic acid) (PASP) derivatives (PASP-BSer) with phenylborate serine (BSer) side groups as the ROS-responsive unit. A series of PASP-BSer conjugates with different degree of substitution (DS) were synthesized, and their self-assembly and H2O2-responsive behaviors were investigated to optimize the structure of PASP-BSer. In vitro drug loading and release studies confirmed that the optimized PASP-BSer micelles could effectively encapsulate the model anticancer drug doxorubicin (Dox) and exhibit desirable H2O2-triggered release behaviors. More importantly, Dox-loaded PASP-BSer micelles showed high selective cytotoxicity against A549 cancer cells than L929 normal cells. Accordingly, PASP-BSer micelles have significant potential as on-demand drug carriers for anticancer therapy.