Simple and sensitive assay for nucleic acids by use of the resonance light-scattering technique with the anionic dye methyl blue in the presence of cetyltrimethylammonium bromide

This is the first report on the determination of nucleic acids based on the enhancement of resonance light scattering (RLS) of the anionic dye methyl blue (MB) in the presence of cetyltrimethylammonium bromide (CTMAB). In tris(hydroxymethyl) aminomethane buffer of pH 9.0, MB and nucleic acids react with CTMAB to form large particles of complex, which results in strong enhanced RLS signals characterized by three peaks at 334 nm, 393.5 nm and 548 nm. Mechanistic studies show that the enhanced RLS stems from the aggregation of MB on nucleic acids through the bridged and synergistic effect of CTMAB. With the enhanced RLS signals at the best wavelength at 334 nm, the enhanced RLS intensity is proportional to the concentration of nucleic acids in a wide range. The lowest limit of determination was 2.1 ng mL⁻¹, three synthetic samples were analyzed satisfactorily.