Electrophoresis and fluorospectrophotometry methods to determine the content and entrapment efficiency of siRNA in cationic liposomes

To develop different methods for determining siRNA content and the entrapment efficiency of siRNA loaded liposomes, SYBR Gold electrophoresis method and Ribogreen fluorospectrophotometry method were used respectively.  SYBR Gold electrophoresis method has a good linear relation in a range at 0.2 - 2.0 μmol·L^-1 (R = 0.993 0), and the recovery at the high, middle and low concentrations were 96.35%, 96.92%, and 100.74%, respectively (n = 3).  The intra-day and inter-day RSD were far below 5% (n = 5). Ribogreen fluorospectrophotometry method has a good linear relation in a range at 10 - 50 nmol·L^-1 (R = 0.997 1), and the recovery at the high, middle and low concentrations were 98.22%, 99.88% and 99.64%, respectively (n = 3).  The intra-day and inter-day RSD were far below 5% (n = 5).  The content and the entrapment efficiency of three batches of siRNA cationic liposomes were 98.52%, 97.85% and 99.20%, 96.45%, respectively, with these two methods.  And there is no significant difference by ANOVA.  Both of the two methods are accurate, sensitive, convenient method for determination of the siRNA content and the entrapment efficiency of siRNA loaded   cationic liposomes.