Polydopamine (PDA) possesses high aqueous dispersibility, strong optical absorption, and a zwitterionic property, which give it multitudes of advantages to coat light-sensitive hydrophobic curcumin (Cur) for pH-responsive release. However, PDA is formed in alkaline conditions, which hinders its potential application for alkali-sensitive curcumin coating. Here, we developed a method to prepare PDA-coated Cur nanoparticles (NPs), which reduced chemical degradation of Cur in alkaline conditions. Encapsulation efficiency and loading capacity decreased to 73.69% and 51.80%, as the time for dopamine polymerization went on. PDA could protect Cur from light-induced degradation in powder and solution forms. Controlled release and pH-responsive delivery of PDA-coated Cur were observed under stomach and intestinal conditions compared to free Cur, which resulted from the coverage and thickness of the PDA shell and the electrostatic attraction between PDA and Cur. PDA-coated Cur NPs could be a promising way for the application of Cur in the beverage and food industry.
Keywords: controlled release; curcumin; polydopamine; stability; targeted delivery.