Luminescence determination of DNA using terbium complexes with 2-oxo-4-hydroxyquinoline-3-carboxylic acid amides as probes

It was found that the presence of DNA significantly enhanced the 4f luminescence of terbium(III) in its complexes with a number of 2-oxo-4-hydroxyquinoline-3-carboxylic acid amide derivatives (L₁-L₆). For the high-sensitivity determination of DNA, L₁ and L₄ were chosen from two proposed groups, in complexes with which terbium ions exhibited the most intense luminescence. Under optimum conditions, the luminescence intensity of terbium was proportional to the concentration of DNA over the ranges 0.025–1.2 μg/mL (detection limit of 10 ng/mL) and 0.01–1.2 λg/mL (detection limit of 3 ng/mL) for L₁ and L₄, respectively. The mechanisms of the interaction of Tb-L complexes with DNA molecules were hypothesized.