5 m nitrocellulose membrane filter

Lu-NLC was diluted in milli-Q water (1:5, v:v), filtered in a 5 µm nitrocellulose membrane filter (Millipore, Dublin, Ireland) and diluted 1:10 (v:v) in ethanol to extract Lu from the NLC. The mixture was centrifuged at 4620× g at 25 °C for 15 min; the supernatant was collected and filtered through a 0.45 µm PTFE syringe filter (Millipore, Ireland) [46 (link)]. The supernatant was diluted (1:6, v:v) in an eluent solution and applied to the HPLC column. The amount of Lu released was quantified using a standard curve constructed with a known concentration of Lu (20 a 70 μg/mL). Encapsulation efficiency (EE) was determined by calculating the amount of Lu in the supernatant of the filtered formulations as follows: $$EE\%=\frac{\mathrm{Amount} \mathrm{of} \mathrm{Lu} \mathrm{in} \mathrm{the} \mathrm{filtered} \mathrm{formulation}}{\mathrm{Total} \mathrm{amount} \mathrm{of} \mathrm{Lu}}\times 100$$

The freshly prepared formulation was diluted in milli-Q water (1:5), filtered through a 5 µm nitrocellulose membrane filter (Millipore, Ireland), and diluted 1:10 in ethanol to extract UA from NLC. The mixture was centrifuged at 4620× g at 25 °C for 15 min (Thermo Scientific Heraeus Multifuge X1R Refrigerated Benchtop Centrifuge, Indianapolis, IN, USA), the supernatant collected, and filtered through a 0.45 µm PTFE syringe filter (Millipore, Ireland). The supernatant was diluted (1:6) in eluent solution and applied to the HPLC column and the amount of UA released quantified. The encapsulation efficiency (EE) was calculated according to the following equation: $EE\%=\frac{AmountofUAinthefilteredformulation}{TotalamountofUA}\times 100$