Polytron system pt 3100 homogenizer

Synthesis of AstaCO₂-NLC and the appropriate Blank-NLC (astaxanthin-free NLC) were prepared by HH method on the basis of a previously reported methods [7 (link),35 (link)]. Optimization of the work-up procedure was performed where it was needed. Specifically, AstaCO₂ (103 mg) was dissolved at 75 °C in the oil phase, which consists of the solid lipid (Precirol^® ATO 5, 450 mg) and Tween^® 80 as a surfactant (60 mg). The Blank-NLC was prepared by adding sunflower oil (103 mg). In a separate container, surfactant (Poloxamer 407, 450 mg) was dissolved in purified water (16 mL) (aqueous solution) and heated at 75 °C. The oil phase was homogenized at 10,000 rpm for 2 min at 75 °C (Polytron^® system, PT3100 homogenizer with a dispersing aggregate of 7 mm of diameter coupled (Kinematica AG, Luzern, Switzerland). Then, 2 mL of the aqueous solution were added to the oil phase to form the initial water-in-oil emulsion. The rest of the aqueous solution was added dropwise during 10 min into the oil phase under homogenization at 20,000 rpm at constant temperature of 75 °C. After complete addition, the nanoemulsion was cooled down to room temperature (25 °C) for 10 min and the pH was adjusted to pH 8.4. Then the nanoemulsion was stored overnight at 4 °C follow by centrifugation (10,000 rpm, 15 min) to obtain a NLC suspension. A scheme of the synthesis procedure is shown in Figure 1.