Caseinate-zein-polysaccharide complex nanoparticles as potential oral delivery vehicles for curcumin: Effect of polysaccharide type and chemical cross-linking

The formation of protein-polysaccharide complex nanoparticles was investigated using caseinate (NaCas), zein, and three polysaccharides, i.e. pectin, carboxymethyl cellulose (CMC) and gum arabic. Their complexation behavior was examined by dynamic light scattering, Fourier transform infrared and fluorescence spectroscopy. Chemical cross-linker, 1-ethyl-3-(3-dimethyl aminopropyl) carbodiimide/N-hydroxysuccinimide, were exploited to covalently bridge proteins and polysaccharide to improve the stability of complex nanoparticles in simulated gastrointestinal (GI) fluids. Curcumin was studied as a model lipophilic nutrient to explore the encapsulation and delivery applications. The polysaccharide type significantly affected the cross-linking efficiency which led to distinctive physical stability under simulated GI conditions and completely different morphology of powders obtained by nano spray drying, as well as their redispersibility in water. Compared to gum arabic, pectin and CMC were more favorable to form cross-linked nanoparticles with smaller size (160–210 nm), uniform distribution, spherical shape, higher encapsulation efficiency (up to 80%), slower release and much improved antioxidant activity, as well as exceptional redispersibility after drying. Our study suggested that chemical cross-linking process and selection of polysaccharide should be considered when developing desirable protein-polysaccharide complex nanoparticles that could maintain their integrity under simulated GI conditions for oral delivery applications.