Waters acquity arc system

The encapsulation efficiency (EE) of TPP-SS-ATS-LS was determined by ultrafiltration method. (1) Determination of the total content of TPP-SS-ATS in the liposomes solution (M1): The TPP-SS-ATS-LS were added into the volumetric flask and the TPP-SS-ATS was extracted by ultrasonic extraction with extraction solvent for 15 min at room temperature. The content (M1) of TPP-SS-ATS was determined by Waters ACQUITY Arc system (Waters, USA). (2) Determination of free TPP-SS-ATS content (M2): An appropriate amount of TPP-SS-ATS-LS was added into the ultrafiltration tube (millipore Amicon ultra 4 ml 10 kDa). The ultrafiltration tube was centrifuged at 5000 rpm at 4 ℃ for 120 min to obtain ultrafiltration filtrate and the content (M2) of free TPP-SS-ATS was determined by Waters ACQUITY Arc system (Waters, USA). The average of three parallel experimental data was used to analyze the results. The EE was calculated by the following equation: $$EE(\%)=\frac{M_1-M_2}{M_1}\times 100\%.$$

The extraction and analysis of sulforaphane used the method as described by Guo et al. [26 (link)], with some modifications. Broccoli microgreens (0.5 g fresh shoots) were ground with 1 mL of distilled water. After 3 h of incubation at 37 °C, the microgreens homogenate was extracted three times with 10 mL of dichloromethane. The dichloromethane fraction was dried at 35 °C under vacuum on a rotary evaporator. The residue was dissolved in 2 mL of acetonitrile and through a 0.22 µm membrane filter. The extracts were analyzed using a Waters ACQUITY Arc system (Waters Co., Milford, MA, USA) that was equipped with a 2489 UV/Vis detector, using a prontosil ODS 2 column (250 × 4 µm, 5 µm, Bischoff, Leonberg, Germany). The flow rate was 0.6 mL/min in a linear gradient of 10–60% acetonitrile from 0 to 25 min, reaching 100% acetonitrile at 30 min. The absorbance value was 254 nm. Sulforaphane (Sigma Chemical Corporation, St. Louis, MO, USA) was used as an external standard.