Novel amphiphilic carboxymethyl curdlan-based pH responsive micelles for curcumin delivery

Abstract

In this study, a novel octenyl succinic anhydride modified carboxymethyl curdlan (OSA-CMCD) amphiphilic polymer was prepared for the encapsulation and release of curcumin. Four amphiphilic OSA-CMCD polymers with different degree of substitutions (DSs) were first synthesized. The critical micelle concentration was decreased from 0.0960 to 0.0455 mg/mL with increase in the DS from 0.0306 to 0.6375. The amphiphilic copolymers self-assembled micelles were monodispersed and spherical with a particle size of 157.95–200.57 nm. After curcumin encapsulation, the micelles showed a larger particle size, a smaller polydispersity index, and an increased absolute zeta potential in the ranges of 210.3–237.07 nm, 0.152–0.223, and 40.17–48.33 mV, respectively. The maximum encapsulation efficiency (85.49%) and loading capacity (7.77%) were observed when the DS of CMCD-OSA polymer was 0.047. Curcumin could be embedded into micelles in an amorphous form. The curcumin loaded micelles displayed a slow release profile in PBS at pH 1.2 or 6.8, whereas 68.00% of curcumin was released when micelles were dissolved in pH 7.4, suggesting a sustained pH-dependent drug release. These results demonstrated that OSA-CMCD micelles have potential utility in encapsulation, dissolution and colon-targeted delivery of hydrophobic ingredients in the food and biomedical industries.