Rapid and sensitive ethidium bromide fluorescence quenching assay of polyamine conjugate-DNA interactions for the analysis of lipoplex formation in gene therapy
Aj. Geall et Is. Blagbrough, Rapid and sensitive ethidium bromide fluorescence quenching assay of polyamine conjugate-DNA interactions for the analysis of lipoplex formation in gene therapy, J PHARM B, 22(5), 2000, pp. 849-859
A rapid and sensitive fluorescent assay method is reported for assessing po
lyamine conjugate-calf thymus DNA binding affinity using cholesterol polyam
ine carbamates with ethidium bromide as a probe. A reproducible method has
been developed with an optimal excitation wavelength. Salt concentration is
shown to be a critical parameter for both the observed fluorescence intens
ity of ethidium intercalated in DNA, and also for the binding of positively
charged polyammonium ions to DNA, effecting charge neutralisation. This ch
arge neutralisation precedes DNA condensation, a key first step in gene the
rapy. (C) 2000 Elsevier Science B.V. All rights reserved.