Encapsulation of astilbin in zein nanoparticles with fructo-oligosaccharides and caseinate as costabilizers: Formation, stability, bioavailability, and antioxidant capacity

Zein-based nanoparticles (NPs) have attracted considerable attention as potential delivery systems for bioactive compounds. However, their application has been limited by poor stability and redispersibility. In this study, we addressed these challenges by fabricating zein nanocarriers using branching structural fructo-oligosaccharides (P-FOS) and sodium caseinate (NaCas) as costabilizers. P-FOS and NaCas were incorporated through an antisolvent coassembled precipitation technique. Astilbin (Ast) served as a model lipophilic bioactive compound to evaluate this innovative nanocarrier system. The results showed that Ast-loaded zein/P-FOS/NaCas nanoparticles (AZPS NPs) were successfully prepared, featuring a distinct spherical core-shell structure with a mean particle size of 156.4 +/- 2.1 nm, zeta potential of -27.5 +/- 3.5 eV and a uniform size distribution. Microstructural analysis using Fourier transform infrared spectroscopy, X-ray diffraction, and high-resolution transmission electron microscopy with energy-dispersive X-ray spectroscopy revealed that electrostatic interactions, hydrophobic interactions, and intermolecular hydrogen bonding contributed to the formation of the composite NPs. Compared to Ast-loaded zein NPs stabilized solely with NaCas (AZS), AZPS NPs exhibited superior stability under various environmental conditions (temperature, pH, and ionic strength) and demonstrated exceptional redispersibility after freeze drying. They also achieved an efficient Ast encapsulation rate of 92.3 % and a loading capacity of 12.4 %, compared to 73.56 % and 13.3 % in AZS, along with significantly enhanced bioavailability (2.4-fold) and antioxidation activity of Ast. Our findings suggest that P-FOS and NaCas are effective costabilizers for zein NPs, providing new insights into the application of fructans in zein-based composite NPs for the efficient delivery of hydrophobic bioactive compounds in cosmetics, pharmaceuticals, and food industries.