engleski

The determination of DNA entrapment into liposomes using short monolithic columns

The entrapment of DNA into liposomes enhances the potency of DNA vaccines1. In the process of DNA-containing liposome preparation and characterisation, it is necessary to determine the quantity of DNA entrapped within or complexed to liposome vesicles. The most widely used method is the one that uses the radioactively labelled DNA2. In this study we describe the development of the indirect non-radioactive method using short monolithic columns for the measurement of DNA entrapment that does not require any kind of DNA labelling. Non-entrapped DNA from the supernatant of centrifuged liposomes was chromatographed on CIM DEAE disk and detected by absorbance at 260 nm. The unknown quantity of DNA in samples was calculated from the integrated peak areas using standard curve. Finally, the method was used to determine the efficiency of pCMV (HBs) entrapment within cationic liposomes at various charge ratios. (1) G. Gregoriadis, R. Saffie, B. Souza, FEBS Letters, 402, 107-110 (1997) (2) P.A Monnard, T. Oberholzer, P.L. Luisi, Biochimica et Biophysica Acta, 1329, 39-50 (1997)

entrapment efficiency; liposomes; CIM disk

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