Fabrication, characterization, physicochemical stability of zein-chitosan nanocomplex for co-encapsulating curcumin and resveratrol

The present study aimed at the design and fabrication of a novel co-delivery system to encapsulate and protect curcumin and resveratrol. Curcumin and resveratrol had synergistic physiological activities when used together, but it was challenging to co-encapsulate them in traditional delivery vehicles due to their difference in molecular polarity. The curcumin-zein-resveratrol-chitosan nanocomplexes were developed and their formation mechanism and physicochemical properties were investigated. Hydrogen bonding and hydrophobic effects were dominant binding forces to stabilize the nanocomplexes. As the relative molecular weight of chitosan was increased, the mean size and surface positive charge of the nanocomplexes were elevated. The optimized nanocomplex based on zein and low molecular weight chitosan (50000-190000 Da) had a relatively high encapsulation efficiency of curcumin (91.3 %) and resveratrol (82.1 %), as well as exhibited the best physical stability. In addition, the half-life times of curcumin and resveratrol in the nanocomplex were extended by 4.5- and 1.9-fold during photodegradation, and the retention rates were increased by 3.7- and 1.1-fold than their free forms during thermal degradation. The nanocomplexes could also remain stable and delay the degradation of both bioactive compounds during long term storage. In summary, the nanocomplex showed to be an effective vehicle for the co-delivery of synergistic nutraceuticals.