Study of interaction of ciprofloxacin probe and calf thymus DNA using fluorescence spectrometry

The interaction of ciprofloxacin and calf thymus DNA (ctDNA) was studied using UV spectrometry and fluorescence spectrometry. Ciprofloxacin exhibited a fluorescence excitation at 270 nm and a fluorescence emission at 420 nm in pH 7.0 phosphate buffer solutions due to the groove binding of ciprofloxacin on calf thymus ctDNA. The binding constant was 2. 64 X 104 mol(-1) x L(25 degrees C). Based on the fluorescence quenching, a novel method for sensitive determination of calf thymus ctDNA concentration ranging from 80 nmol x L(-1) to 45 micromol x L(-1) was developed. The relative standard deviation for eleven detections of 25 micromol x L(-1) ctDNA was 4. 2%.