2.1. Materials
Pine sterol (91.0% β-sitosterol, 7.0% campesterol, 0.5% stigmasterol, 0.3% brassicasterol, and 1.2% others) was kindly donated from Jiangsu Conat Biological Products Co., Ltd (Jiangsu, China); diatomite (200 mesh) was purchased from Aladdin (Shanghai, China); FeCl3·6H2O, FeCl2·4H2O, 3-mercaptopropyltriethoxysilane (97%), n-octadecyltriethoxysilane (85%), Oleic acid (99.0%) were purchased from Sarn Chemical Technology Co., Ltd (Shanghai, China).Candida rugosa lipase (type VII) was purchased from Sigma-Aldrich (St. Louis, MO, USA).