Study on a fluorescence-enhanced system of 1,2,4-trihydroxyanthroquinone–Be 2+–DNA

Abstract

Fluorescence-enhancement of 1,2,4-trihydroxyanthroquinone (THAQ)–Be 2+ complex enhanced by nucleic acid was studied. Experimental results revealed that double-stranded DNA can enhance remarkably the fluorescence intensity of THAQ–Be 2+, while RNA cannot. Based on these results, a fluorescence method for the selective determination of DNA in the presence of RNA was developed. Maximum fluorescence intensity was found in the pH range 3.6–4.5 with maximum excitation and emission wavelengths at 510 and 565 nm, respectively. Under optimum conditions, the calibration graph was linear over the range 0.08–18 μg ml −1 for double-stranded fish sperm DNA (fsDNA) with the detection limit being 2.75×10 −8 g ml −1. The method was applied for the determination of DNA in synthetic samples. The relative S.D. for five replicates was within 4%. In addition, the interaction mechanism of THAQ–Be 2+ with DNA was also discussed.