The siRNA encapsulation efficiency of liposomes was evaluated as described below, using
the ultrafiltration method. In short, 2 mL FAM-siRNA loaded liposome solution was taken
out and added into the Ultra-4 centrifugal filter devices (EMD Millipore, Billerica, MA,
USA). Then, the centrifugation was performed, with the desk centrifuge (30 minutes at
3,500 × g), aiming to remove the unencapsulated siRNA. After
centrifugation, 4 mL deionized water was added again, and the centrifugation was repeated.
The ultrafiltration was performed for four times, and unencapsulated FAM-siRNA was
gathered. In the end, the FAM-siRNA was quantified by the constructed calibration line of
FAM-siRNA. Using the Synergy™ 4 (BioTek Instruments, Inc., Winooski, VT, USA), the
fluorescence of FAM-siRNA was examined (wavelength of excitation: 495 nm, wavelength of
emission: 525 nm). The siRNA encapsulation efficiency was calculated with the formula:
(the mass of total siRNA minus the mass of unencapsulated siRNA)/the mass of total siRNA
× 100%.
The evaluation of the stability of liposomes was performed as follows. First, the
liposomes were suspended in various media, including PBS, PBS with 10% FBS, or 20% FBS.
Then the solution was incubated at 25°C for 5 days. In each day, an aliquot of
liposomes was taken out for the analysis of the size change of liposomes.
the ultrafiltration method. In short, 2 mL FAM-siRNA loaded liposome solution was taken
out and added into the Ultra-4 centrifugal filter devices (EMD Millipore, Billerica, MA,
USA). Then, the centrifugation was performed, with the desk centrifuge (30 minutes at
3,500 × g), aiming to remove the unencapsulated siRNA. After
centrifugation, 4 mL deionized water was added again, and the centrifugation was repeated.
The ultrafiltration was performed for four times, and unencapsulated FAM-siRNA was
gathered. In the end, the FAM-siRNA was quantified by the constructed calibration line of
FAM-siRNA. Using the Synergy™ 4 (BioTek Instruments, Inc., Winooski, VT, USA), the
fluorescence of FAM-siRNA was examined (wavelength of excitation: 495 nm, wavelength of
emission: 525 nm). The siRNA encapsulation efficiency was calculated with the formula:
(the mass of total siRNA minus the mass of unencapsulated siRNA)/the mass of total siRNA
× 100%.
The evaluation of the stability of liposomes was performed as follows. First, the
liposomes were suspended in various media, including PBS, PBS with 10% FBS, or 20% FBS.
Then the solution was incubated at 25°C for 5 days. In each day, an aliquot of
liposomes was taken out for the analysis of the size change of liposomes.