Simple and sensitive determination of nucleic acids using palladium(II) complex with 2-(2-thiazolylazo)-5-dimethylaminobenzoic acid

The paper describes the use of the palladium(II) complex with 2-(2-thiazoly lazo)-5-dimethylamino-benzoic acid (TAMB) for the spectrophotometric determ ination of nucleic acids with the detection limit at ng levels. At pH 5.9, Pd(II), TAME and nucleic acids interact rapidly at room temperature to form a supermolecular complex, leading to absorbance decreases at 621 and 675 n m of the palladium(II)-TAMB complex. With 675 nm as the measurement wavelen gth, the calibration linearity for calf thymus DNA (ct DNA), fish sperm DNA (fs DNA), and yeast RNA extend up to 3.5, 3.5 and 2.0 mu g ml(-1), respect ively, with corresponding 3 sigma detection of 22, 27 and 25 ng ml(-1). Rel ative standard deviations for the synthetic samples are within 2.8% (n = 5) . DNA extracted from pig liver is determined with a calibration graph for c t DNA, the result being very close to obtained by ethidium bromide fluorime try. Compared to other colorimetric nucleic acids assays, the outstanding a spects of the present method are its sensitivity, simplicity and practicali ty. By the Rosenthanl and Meehan graphical procedures, the binding number a nd association constant of ct DNA with the complex are estimated, and the b inding reaction is considered to be an intercalation. (C) 2000 Elsevier Sci ence B.V. All rights reserved.