Study on bromocresol green-cetyltrimethylammonium-deoxyribonucleic acids system by resonance light scattering spectrum methods

An assay of deoxyribonucleic acids (DNA) determination, with the sensitivity at nanogram level, was established in the present study by using a common spectrofluorometer to detect the intensity of resonance light scattering (RLS). In hexamethylene tetramine (HMTA) buffer (pH 11.00), Bromocresol Green (BCG) and deoxyribonucleic acids (DNA) react with cetyltrimethylammonium bromide (CTMAB) to form large particles of three-component complex, which results in strong enhanced RLS signals characterized by three peaks at 336, 390, and 622 nm and at 336 nm that is the strongest of the three enhanced RLS peaks. Mechanistic studies showed that the enhanced RLS stems from the aggregation of BCG on DNA through the bridged and synergistic effect of CTMAB. Yeast DNA (yDNA), in the range of 0.05-0.90 ng ml−1, fish sperm DNA (fsDNA) in the range of 0.05-0.80 ng ml−1, and calf thymus DNA (ctDNA) in the range of 0.05-0.80 ng ml−1 can be determined if 2.0 × 10−6 mol l−1 BCG was employed. The determination limit of yDNA was 12.7 ng ml−1. Three synthetic samples of yDNA were analyzed with good reproducibility.