Zein/soluble soybean polysaccharide composite nanoparticles for encapsulation and oral delivery of lutein

In this work, zein/soluble soybean polysaccharide (SSPS) composite nanoparticles were fabricated using a facile antisolvent precipitation method to encapsulate lutein. The ternary system can self-assemble to spherical nanoparticles (about 200 nm) with relatively uniform size (PDI around 0.15) and negative charge (about -33.56 mV). For the 25:1 mass ratio of zein to lutein, the encapsulation efficiency was higher than 80%. Notably, the encapsulation was dominated by zein which could bind lutein and form zein-lutein complexes spontaneously in aqueous ethanol. The aqueous solubility and chemical stability of lutein were both enhanced greatly upon encapsulation. The composite nanoparticles also showed exceptional pH stability and elevated salt stability. Cytotoxicity assay indicated thee nanocarriers are non-toxic and biocompatible. The bioaccessibility of encapsulated lutein (32.11%) was greatly higher than that of non-encapsulated lutein (16.21%). These results suggested that zein/SSPS composite nanoparticles may be a promising delivery system for lutein, which could be used as an ingredient for the formulation of beverages or functional foods.