Characterisation of the binding interaction between poly(L-lysine) and DNAusing the fluorescamine assay in the preparation of non-viral gene delivery vectors

A major factor limiting the development of non-viral gene delivery systems is the poor characterisation of polyelectrolyte complexes formed between ca tionic polymers and DNA. The present study uses the fluorescamine reagent t o improve characterisation of poly(L-lysine) (pLL)/DNA complexes post-modif ied with a multivalent hydrophilic polymer by determining the availability of free amino groups. The results show that the fluorescamine reagent can b e used to monitor the self-assembly reaction between pi,, and DNA and the d egree of surface modification of the resultant complexes with a hydrophilic polymer. This experimental approach should enable the preparation of fully defined complexes whose properties can be better related to their biologic al activity. (C) 1999 Federation of European Biochemical Societies.