Self-assembled micelles of dual-modified starch via hydroxypropylation and subsequent debranching with improved solubility and stability of curcumin

The purpose of this study was to fabricate curcumin-encapsulated self-assembled micelles by dual-modified starch (hydroxypropylation and subsequent debranching) to improve the water solubility and stability of curcumin. Double modified starches with different amylose content (13%, 30% and 47%) were prepared by controlling the debranching time. Fluorescent probe method showed that the dual-modification of hydroxypropylation and debranching is necessary for the formation of self-assembled micelles, and dual-modified starch with 13% amylose content has the strongest self-assembly ability (the lowest critical micelle concentration, 0.43 mg/mL). The self-assembled micelles exhibited a particulate morphology with a size of about 80–200 nm. Cytotoxicity and hemolysis evaluation confirmed the good cytological compatibility (cell viability > 90%) as well as hematological compatibility (hemolysis rates < 5%) of the self-assembled micelles as nano-oral systems. Curcumin was encapsulated into self-assembled micelles by the self-assembly (encapsulation efficiency, 70.33%; loading capacity, 5.33%). The water solubility and stability of curcumin were successfully improved (200-fold and 3-6-fold compared to free curcumin, respectively), which was attributed to the encapsulation of hydrophilic core in the self-assembled micelles, and the hydrophobicity and hydrogen bonding provided by hydroxypropyl. In vitro gastrointestinal sequential release simulations confirmed the sustainable release of curcumin, and First-order and Korsmeyer-Peppas modeling for curcumin were confirmed to be the best release models in the gastric and intestinal phases, respectively. Based on the above, the self-assembled micelles of dual-modified starch would potentially serve as a curcumin-encapsulated nanocarrier to improve the oral bioavailability and shelf life of curcumin in food, medical and cosmetic applications.