Preparation and characterization of zein/chitosan complex for encapsulation of α-tocopherol, and its in vitro controlled release study

Chitosan (CS) nanoparticles coated with zein has been newly demonstrated as a promising encapsulation and delivery system for hydrophilic nutrient with enhanced bioactivities in our previous study. In this study, a hydrophobic nutrient, α-tocopherol (TOC), was successfully encapsulated into zein/CS complex. The fabrication parameters, including zein concentration, zein/CS weight ratio, and TOC loading percentage, were systematically investigated. The physicochemical and structural analysis showed that the electrostatic interactions and hydrogen bonds were major forces responsible for complex formation. The scanning electron microscopy study revealed the spherical nature with smooth surface of complex. TOC encapsulation was also evidenced by differential scanning calorimetry. The particle size and zeta potential of the complex varied from 200 to 800 nm and +22.8 to +40.9 mV, respectively. The kinetic release profile of the TOC showed burst effect followed by slow release. Compared with zein nanoparticles, zein/CS complex provided better protection of TOC release against gastrointestinal conditions, due to CS coatings. Zein/CS complex is believed to be a promising delivery system for supplementation or treatment of hydrophobic nutrients or drugs.