PURPOSE: To validate Fluorescence Resonance Energy Transfer (RET) as method to monitor disintegration of fluorescently labeled liposomes varying in lysolecithin/oleic acid (equimolar) content, lysolecithin fatty acid composition and vesicle size in rat blood plasma and buffer. METHODS: NBD-PE and Rho-PE were used for RET. The measurements were performed on a Perkin Elmer LS-50 spectrofluorimeter. Liposomes were prepared by the extrusion method. RESULTS: Analysis of the RET data was optimised using a fitting procedure to correct for fluorescence interference by plasma. The disintegration patterns of liposomes could be described by a biexponential decay model. Disintegration rate increased at increasing lysolecithin/oleic acid content and decreasing size. In contrast, all liposomes showed no disintegration in buffer. CONCLUSIONS: RET is a suitable method to monitor liposome disintegration in non-diluted plasma. Rate and extent of liposome disintegration increases at decreasing liposome size and increasing lysolecithin/oleic acid content.
PURPOSE: To validate Fluorescence Resonance Energy Transfer (RET) as method to monitor disintegration of fluorescently labeled liposomes varying in lysolecithin/oleic acid (equimolar) content, lysolecithin fatty acid composition and vesicle size in rat blood plasma and buffer. METHODS: NBD-PE and Rho-PE were used for RET. The measurements were performed on a Perkin Elmer LS-50 spectrofluorimeter. Liposomes were prepared by the extrusion method. RESULTS: Analysis of the RET data was optimised using a fitting procedure to correct for fluorescence interference by plasma. The disintegration patterns of liposomes could be described by a biexponential decay model. Disintegration rate increased at increasing lysolecithin/oleic acid content and decreasing size. In contrast, all liposomes showed no disintegration in buffer. CONCLUSIONS: RET is a suitable method to monitor liposome disintegration in non-diluted plasma. Rate and extent of liposome disintegration increases at decreasing liposome size and increasing lysolecithin/oleic acid content.