Determination of nucleic acid by its enhancement effect on the fluorescence of Ellagic acid – Cationic surfactant system

In this paper, nucleic acid can greatly enhance the fluorescence of Ellagic acid (EA) in the presence of cetylpyridine bromide (CPB). Experiments indicate that under the optimum conditions, the enhanced intensity of fluorescence is proportional to the concentration of nucleic acid in the range of 5.0 × 10−9–3.5 × 10−5 g mL−1 for hsDNA, 5.0 × 10−9–3.5 × 10−5 g mL−1 for ctDNA and 5.0 × 10−9–3.5 × 10−5 g mL−1 for yRNA. Their detection limits (S/N = 3) are 7.6 × 10−9 g mL−1, 8.6 × 10−9 g mL−1 and 6.1 × 10−9 g mL−1, respectively. The method has been satisfactorily used for the determination of nucleic acid in actual samples. Resonance Light Scattering, Ultraviolet and other means are used to discuss its mechanism. It is considered that the charge–transfer complex EA–CPB aggregate in the extended nucleic acids by hydrogen bond and electric attraction. The hydrophobic microenvironment of nucleic acid makes the fluorescence intensity of EA–CPB–nucleic acid system much stronger.