Hybridization of Genomic DNA Adsorbed Electrostatically onto Cationic Surfaces

Our previous study revealed an intriguing phenomenon of partial hybridization of two single strands of genomic DNA, with one of them being electrostatically adsorbed on a solid surface. Although the effect was confirmed with different methods and even recommended for a crude DNA analysis, the exact mechanism of hybridization was not clear. This work presents the results of more detailed study of adsorption and hybridization of two genomic DNA, of salmon and herring, using the experimental techniques of total internal reflection ellipsometry (TIRE), ATR FTIR spectroscopy, and AFM. The in situ TIRE study of the hybridization kinetics allowed the evaluation of the association constant. It appeared to be in the range of 105 mol-1 L for binding complementary ss-DNA in comparison to 104 mol-1 L for binding of noncomplementary ss-DNA. FTIR study directly confirmed the effect of partial binding of complementary ss-DNA by monitoring the 1650 and 1690 cm-1 spectral bands. AFM showed the transformation from clearly resolved images of separate chains of ss-DNA molecules adsorbed on the surface of mica to an inhomogeneous layer of tangled and overlapping DNA molecules following binding of another complementary ss-DNA.