Phytosterol delivery system based on crosslinked chitosan-modified nanostructured lipid carriers: Enhancing stability and digestive absorption

Phytosterols (PS) are natural steroidal compounds with multiple physiological functions, but their poor solubility, high crystallinity, and low bioavailability hinder effective utilization. In this study, PS-loaded nanostructured lipid carriers modified with cross-linked chitosan (CLCS-PS-NLCs) developed via emulsification-evaporation combined with high-pressure homogenization. The optimal formulation was achieved with 0.5 % (w/w) chitosan and a tripolyphosphate (TPP):chitosan (CS) mass ratio of 2:1 to enhance carrier stability and PS absorption. Structural characterization using dynamic light scattering (DLS) and transmission electron microscopy (TEM), along with fourier transform infrared (FTIR), X-ray diffraction (XRD), and differential scanning calorimetry (DSC), confirmed efficient PS encapsulation and successful chitosan modification. CLCS-PS-NLCs demonstrated excellent stability under varying pH, ionic strength, and storage conditions. In vitro and in vivo studies showed improved digestion and absorption of PS, achieving a bioaccessibility of 36.65 % compared to only 13.28 % for PS-NLCs, and enhancing its uptake in rats. This study provides a promising delivery system for PS with potential applications in functional foods and pharmaceuticals.