Study of the reaction between nucleic acids and the trihydroxyanthroquinone–Al complex and its analytical application

Abstract

The reaction between nucleic acids and the trihydroxyanthroquinone (THAQ)–Al complex was studied. The nucleic acids used were fish sperm DNA (fsDNA), calf thymus DNA (ctDNA) and yeast RNA (yRNA). Experiments indicated that the addition of a very small amount of double-stranded DNA quenched the fluorescence of the THAQ–Al complex. When the mole ratio R of DNA to Al 3+ was 0.53, the fluorescence quenching was a maximum. If R >0.53, the fluorescence increased gradually until a constant value was obtained. If DNA was replaced by RNA or denatured DNA, only a fluorescence quenching effect was observed. Under optimum conditions, the calibration graphs were linear over the range 3.8 × 10 −8–1.75 × 10 −6 g ml −1 fsDNA, 5.0 × 10 −8–1.5 × 10 −6 g ml −1 ctDNA and 2.0 × 10 −8–1.5 × 10 −4 g ml −1 yRNA. The detection limits were 6.6 × 10 −9 g ml −1 fsDNA, 7.3 × 10 −9 g ml −1 ctDNA and 5.4 × 10 −9 g ml −1 yRNA. The method was applied to the determination of DNA or RNA in synthetic samples. The mechanism of the interaction between THAQ–Al and nucleic acids was also discussed.