4.3.1. Curcumin β-Cyclodextrin Complex

The curcumin β-cyclodextrin inclusion complex was prepared by the saturated aqueous solution method. Briefly, different proportions of β-cyclodextrin (β-CD) and curcumin were dissolved in deionized water and absolute ethanol, respectively (one gram of β-CD is dissolved in 25 mL of deionized water; one gram of curcumin is dissolved in 115 mL of anhydrous ethanol). The curcumin solution was slowly dropped into β-CD solution and mixed using a SN-MS-H280D magnetic stirrer (Shanghai Shangyi Instrument Equipment Co., Ltd., Shanghai, China) at a certain rotational speed at a certain temperature. After stirring, it was placed in the refrigerator at 4 °C for 24 h for precipitation and crystallization. A SHB-IIIA vacuum pump (Shanghai Zhenjie Experimental Equipment Co., Ltd., Shanghai, China) was used for filtration and then dried after washing with anhydrous ethanol.