Characterization and antioxidant activity of β-carotene loaded chitosan-graft-poly(lactide) nanomicelles.

β-Carotene (β-C) is a well-established natural antioxidant agent, but its poor water-solubility, low chemical stability and low bioavailability limit its application in food, pharmaceuticals and cosmetics industries. Thus it is critical to develop an efficient method to improve the water solubility and stability of β-C. In this research, amphiphilic chitosan-graft-poly (lactide) (CS-g-PLA) copolymer was synthesized via a homogeneous ring-opening polymerization (ROP) in ionic liquid. The obtained CS-g-PLA copolymer was able to self-assemble into about 14 nm micelles in water at low concentration, and β-C loaded micelles (β-C/M) had low β-C degradation after 15 days. The antioxidant properties of the β-C/M were investigated by the 2, 2-diphenyl-1-picrylhydrazyl (DPPH) method and ferric reducing antioxidant power (FRAP) method, respectively. Significantly improved antioxidant activity was observed for β-C/M in compare with free β-C. The aqueous dispersion of β-C/M has potential to be applied in the field of functional food and cosmetics.