Fabrication of foxtail millet prolamin/caseinate/chitosan hydrochloride composite nanoparticles using antisolvent and pH-driven methods for curcumin delivery

Co-assembled foxtail millet (FP)-sodium casein (NaCas) nanocomplex and NaCas coated FP nanoparticles (NPs) were produced by using pH-cycle and anti-solvent methods, respectively. Subsequently, the effects of chitosan hydrochloride (CHC) coating on the particle size, surface charge and physicochemical stability of the two different FP/NaCas nanoparticles (NPs) were evaluated. With the addition of CHC, the particle size of NaCas coated FP NPs and co-assembled FP-NaCas nanocomplex significantly increased from 128.3 nm and 69.5 nm to 183.5 nm and 113.8 nm, respectively. The stability of the two kinds of CHC coated FP-based NPs to different pH values and varying ionic strengths was different due to their different NP structures. Using different fabrication formulations, co-assembled FP-NaCas NPs entrapped curcumin in relatively hydrophilic microenvironment and showed higher curcumin retention rate in comparison with NaCas coated FP NPs in terms of long-term storage stability. The results revealed that the produced CHC coated FP/NaCas nanocomplexes could be very beneficial in entrapping and delivering bioactive substances.