Nanosep centrifugal devices with omega membrane molecular weight 10 000

The yield and encapsulation efficiency of a drug-delivery system are the major indices for evaluating a successful manufacture process. For determining the yield of AHP, different-ratio AHP formulations were dissolved in methanol. Each sample was shaken using a mixer for 10 min. After that, the ACM concentration of each sample was analyzed by the above HPLC-analysis method for calculating the yield of AHP. For determining the encapsulation efficiency of AHP, different-ratio AHP formulations were reconstituted in distilled water and then shaken with a mixer for 10 min. After that, 200 μL of each sample was placed into a high-speed centrifugal filter device (Nanosep^® Centrifugal Devices with Omega™ Membrane molecular weight 10,000, Pall Corporation, Port Washington, NY, USA) and then centrifuged at 10,000 rpm (Centrifuge 5430 R; Eppendorf, Hamburg, Germany) for 10 min. The encapsulated part was retained on the upper side of the tube, while the non-encapsulated part of the AHP was collected on the lower side of the tube. The amount of ACM in each sample was determined by the above HPLC analysis method. The yield and encapsulation values were calculated using the following equations: Yield %=ACM weight (mg)theoretical amount of ACM (mg)×100%
Encapsulation efficiency %=theoretical amount of ACM−free amount of ACMtheoretical amount of ACM×100%

Firstly, different ratios MyNF (containing 1 mg MYR) were weighed and placed in a 1.5 mL tube with 1 mL methanol and shaken for 10 min, respectively. The MYR concentration in each sample was evaluated using the HPLC analysis method mentioned above. The encapsulation efficiency of different ratio MyNF formulations (containing 1 mg MYR) was weighed and dissolved with 1 mL distilled water. After that, 500 µL of each sample was placed in a high-speed centrifugal filter device (Nanosep^® Centrifugal Devices with Omega™ Membrane molecular weight 10,000, Pall Corporation, Port Washington, NY, USA) and centrifuged at 10,000 rpm (Centrifuge 5430 R; Eppendorf, Hamburg, Germany) for 10 min. The MYR concentration in each sample was evaluated using the HPLC analysis method mentioned above. The yield and encapsulation efficiency of MyNF were calculated using the following equations (Equations (1) and (2), respectively): $$\mathrm{Yield} (\%)=\frac{\mathrm{actual} \mathrm{amount} \mathrm{of} \mathrm{MYR} \left(\mathrm{mg}\right)}{\mathrm{theoretical} \mathrm{amount} \mathrm{of} \mathrm{MYR} \left(\mathrm{mg}\right)} \times 100\%$$
$$\mathrm{Encapsulation} \mathrm{efficiency} (\%)=\frac{\mathrm{theoretical} \mathrm{amount} \mathrm{of} \mathrm{MYR} \left(\mathrm{mg}\right)-\mathrm{free} \mathrm{amount} \mathrm{of} \mathrm{MYR} \left(\mathrm{mg}\right)}{\mathrm{theoretical} \mathrm{amount} \mathrm{of} \mathrm{MYR} \left(\mathrm{mg}\right)} \times 100\%$$