Polydispersity of liposome preparations as a likely source of peak width in capillary zone electrophoresis

Negatively charged liposomes consisting of phosphatidylcholine/phosphatidylglycerol/cholesterol in various ratios when subjected to capillary zone electrophoresis (CZE) in Tris–HCl (pH 8) buffer of different concentrations have been shown previously to exhibit a size-dependent migration rate at low ionic strength. The present study, focusing on the peak width under those conditions, shows that the polydispersity of liposomes correlated with, and appears to be a dominant source of, the peak width of the liposomes in CZE in a buffer of low ionic strength (2 to 5 mM Tris–HCl buffer, pH 8) at moderate electric field strengths (200 V cm−1 or less). This finding, beyond allowing for the analysis of liposome polydispersity by CZE, suggests that the size-dependent fractionation of liposome preparations by a preparative electrophoretic technique such as free-flow electrophoresis is potentially feasible.