Centrifuge multifuge x3 fr

The encapsulation efficiency of PVA-NPs was determined according to a method described by Durán et al. [17 (link)], with some modifications. PVA-NPs containing 10 ml of deionized water were continuously stirred for 60 min using a magnetic stirrer and centrifuged (Centrifuge Multifuge X3 FR, ThermoScientific) twice for 5 min at 5.000 rpm. Then each supernatant was filtered through the filter papers, the absorbance measurements were done using a UV visible spectrometer (UV-1800, Shimadzu, Kyoto, Japan). The percent encapsulation efficiency was determined using the following equation.

Propolis extract was obtained by using 80 % ethanol as solvent. Firstly, 8 % of ethanolic propolis solution was prepared. The obtained solution was stirred with a magnetic stirrer (IKA C-MAG HS 7, Germany) for 24 h at room temperature and then kept at -20 °C for 3 days to precipitate the impurities. After that, the supernatant was taken and filtered through filter paper. Following the filtration, the solution was first centrifuged (Centrifuge Multifuge X3 FR, Thermo Scientific) twice at -5 °C for 5 min at 4.200 rpm. Afterwards, the supernatant was filtered by passing through a 0.22-μm filter. Removal of the solvent from ethanol extract was done by vacuum evaporation (Heidolph Rotary Evaporator, Laborota 4000, Schwabach, Germany) at 50°C. The resulting propolis extract was kept in the refrigerator at 4 °C until further use.