Determination of nucleic acids using phosphin 3R as a fluorescence probe Original Research Article

A novel fluorimetric method has been developed for rapid determination of DNA and RNA with phosphin 3R (PR) as a fluorescence probe, based on the fluorescence quenching of PR in the presence of DNA or RNA. Maximum fluorescence quenching is observed in the pH range 7.0–8.4, with maximum excitation and emission wavelength at 468 and 505 nm, respectively. Under optimal conditions, the calibration graphs are linear up to 2.0 μg/ml for both calf thymus DNA (CT DNA) and salmon DNA (SM DNA), and up to 1.6 μg/ml for yeast RNA, respectively. The corresponding detection limits are 5.0 ng/ml for CT DNA, 6.0 ng/ml for SM DNA and 13.0 ng/ml for yeast RNA. CT DNA could be determined in the presence of 20% (w/w) yeast RNA, and the relative standard deviation of six replicate measurements is 1.00% for a solution containing 400 ng/ml of CT DNA. Three real samples were determined with satisfactory results. The interaction mechanism for the binding of PR to DNA is also studied; the results of absorption spectra and thermal denaturation experiments suggested the interaction between PR and DNA to be intercalative in nature.