Estimation of the membrane permeability of liposomes via use of eosin Y chemiluminescence catalysed by peroxidase encapsulated in liposomes

The initial rate of horseradish peroxidase (HRP)‐catalysed chemiluminescence (CL) reaction in an aqueous compartment of liposomes was applied to the estimation of membrane permeability of liposomes. HRP‐encapsulated liposomes were prepared by an extrusion method, and a CL reagent and H2O2 were added into the liposomes suspensions. Fluorescein, eosin Y and phloxin B, which are xanthene dyes with different chemical structures, were used as CL reagents. Xanthene dye and H2O2 permeate into the inner phase of liposomes, resulting in initiation of the HRP‐catalysed xanthene dye CL reaction with H2O2. The initial rate of the CL reaction was independent of the xanthene dye used. The reproducibility of the initial rate with eosin Y was better than that with fluorescein and phloxin B. When the membrane permeability of the liposomes was changed by altering the concentration of cholesterol in them, the initial rate of the eosin Y CL reaction was dependent on the membrane permeability of the liposomes. Copyright © 2007 John Wiley & Sons, Ltd.