Spectral studies on the interaction of Acid chrome blue K with nucleic acids in the presence of cetyltrimethylammonium bromide and the confirmation of combined points

The interaction of Acid chrome blue K (ACBK) with nucleic acids in weak basic medium was studied in the presence of cetyltrimethylammonium bromide (CTMAB) based on the measurements of resonance light scattering (RLS), UV–vis, NMR spectra, etc. In hexamethylene tetramine (HMTA) buffer (pH 7.45), ACBK and nucleic acids react with CTMAB to form a ternary complex, which results in strong enhanced RLS signals characterized by four peaks at 285, 335, 405.5 and 548 nm. Mechanistic studies show that the enhanced RLS stems from the aggregation of ACBK on nucleic acids through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the best wavelength at 335 nm, the enhanced RLS intensity is proportional to the concentration of nucleic acids in a wide range. The lowest limit of determination was 7.52 ng ml−1, three synthetic samples were analyzed satisfactorily. And the combined points of the anionic dye ACBK with nucleic acids–CTMAB have been tentatively confirmed through the measurement of 1H NMR spectra.