Novel self-assembled pH-responsive biomimetic nanocarriers for drug delivery

• pH responsive biomimetic chitosan derivative NAcHis-PCCs was synthesized.
• Self-assembled NAcHis-PCCs nanoparticles showed acid-induced size increase.
• NAcHis-PCCs nanoparticles with PC shell could avoid adverse biological response.
• QUE/NAcHis-PCCs nanoparticles exhibited an acid triggered drug release behavior.

Novel pH-responsive biodegradable biomimetic nanocarriers were prepared by the self-assembly of N-acetyl-l-histidine-phosphorylcholine-chitosan conjugate (NAcHis-PCCs), which was synthesized via Atherton-Todd reaction to couple biomembrane-like phosphorylcholine (PC) groups, and N,N′-carbonyldiimidazole (CDI) coupling reaction to link pH-responsive N-acetyl-l-histidine (NAcHis) moieties to chitosan. In vitro biological assay revealed that NAcHis-PCCs nanoparticles had excellent biocompatibility to avoid adverse biological response mainly owing to their biomimetic PC shell, and DLS results confirmed their pH-responsive behavior in acidic aqueous solution (pH ≤ 6.0). Quercetin (QUE), an anti-inflammatory, antioxidant and potential anti-tumor hydrophobic drug, was effectively loaded in NAcHis-PCCs nanocarriers and showed a pH-triggered release behavior with the enhanced QUE release at acidic pH 5.5 compared to neutral pH 7.4. The results indicated that pH-responsive biomimetic NAcHis-PCCs nanocarriers might have great potential for site-specific delivery to pathological acidic microenvironment avoiding unfavorable biological response.

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