Nanosep centrifugal device 3k omega

Encapsulation efficiency (EE, %) and loading capacity (LC, %) were assessed for samples A. sibirica resin-, abietic acid- and TMZ-loaded lipid nanosystems. These parameters were determined indirectly by filtration/centrifugation, measuring free TMZ (non-encapsulated) by spectrophotometry. A volume of 0.1 mL of each A. sibirica resin-, abietic acid- and TMZ-loaded liposomes was placed in centrifugal filter devices in a Nanosep centrifugal device 3K Omega (Pall Corporation, New York, USA) to separate the lipid and aqueous phase and centrifuged at 10,000 rpm, for 15 min (Eppendorf AG, Hamburg, Germany). Free TMZ was quantified by measuring the absorbance dilution (Figure S1, Supplementary Materials) using a UV-1800 Shimadzu spectrophotometer at 330 nm (the molar extinction coefficient of TMZ at 330 nm is 9525 M⁻¹·cm⁻¹ at pH = 4 in an acetate buffer after suitable dilution (Figure S1, Supplementary Materials). The encapsulation parameters were calculated against appropriate calibration curve, using the following equations: $$EE\left(\%\right)=\frac{Total amount of drug-Free drug}{Total amount of phospholipid}\times 100\%,$$
$$LC\left(\%\right)=\frac{Total amount of drug-Free drug}{Total amount of phospholipid}\times 100\%,$$

Encapsulation efficiency (EE, %) and loading capacity (LC, %) were assessed for samples containing rhodamine B. These parameters were determined indirectly by filtration/centrifugation technique, measuring free rhodamine B (non-encapsulated) by spectrophotometry. A volume of 50 µL of each rhodamine B-loaded liposomes was placed in centrifugal filter devices Nanosep centrifugal device 3K Omega (Pall Corporation) to separate lipid and aqueous phases and centrifuged at 10,000 rpm for 30 min using centrifuge MiniSpin plus (Eppendorf AG, Hamburg, Germany). Free rhodamine B was quantified by UV absorbance using PerkinElmer λ35 (Perkin Elmer Instruments, Waltham, MA, USA) at 554 nm (ε = 106,089 M⁻¹ cm⁻¹ in 0.0025 M phosphate buffer at pH = 7.4). The encapsulation parameters were calculated against appropriate calibration curve, using the following equation: $$\mathrm{EE}(\%)=\frac{\mathrm{Total} \mathrm{amount} \mathrm{of} \mathrm{RhodB}-\mathrm{Free} \mathrm{RhodB}}{\mathrm{Total} \mathrm{amount} \mathrm{of} \mathrm{RhodB}}\times 100\%$$
$$\mathrm{LC}(\%)=\frac{\mathrm{Total} \mathrm{amount} \mathrm{of} \mathrm{RhodB}-\mathrm{Free} \mathrm{RhodB}}{\mathrm{Total} \mathrm{amount} \mathrm{of} \mathrm{phospholipid}}\times 100\%$$