Fabrication and characterization of biocompatible hybrid nanoparticles from spontaneous co-assembly of casein/gliadin and proanthocyanidin

Abstract Proanthocyanidins (PACs), a group of polyphenolic secondary metabolites in plants, have drawn great interest because of their enormous potential in reducing the incidence of myocardial infarction and death from cardiovascular disease. However, their activities are sensitive to pH, temperature, and light, which limit their applications. For the first time, we developed an easy method to fabricate protein-PAC hybrid nanoparticles via the simple affinity binding between casein or gliadin and PAC. The effects of variable processing parameters (such as ratios of protein and PAC, protein concentration, sodium chloride content, pH, and time) on the characterization of the nanocomplexes were probed. Under optimal conditions, the nanocomplexes were regular shapes approximately 30 nm in size, as observed by transmission electron microscopy. The antioxidant capacity of nanocomplexes improved 12%, 26%, and 14% over that of pure PAC with sodium chloride (0.8 M), ultraviolet radiation (10 w), and heating treatment (80 °C, 30 min), respectively. No cytotoxicity for normal liver cells was found in any of the nanocomplexes measured by methyl thiazolyl tetrazolium assay. Conversely, protein-PAC hybrid nanoparticles exhibited clear cytotoxicity against liver hepatocellular carcinoma (HepG2 cells). This simple approach to fabricating nanocomplexes by co-assembling natural protein with bioactive compounds may open a new avenue to encapsulating and delivering sensible pharmaceuticals and drugs, with potential applications in functional foods, drugs, and personal care products.