Determination of nucleic acids based on shifting the association equilibrium between tetracarboxy aluminum phthalocyanine and poly-lysine

A new method based on near-infrared (near-IR) fluorescence recovery was presented for the determination of nucleic acids. This method employed a two-regent system composed of anionic tetracarboxy aluminum phthalocyanine (AlC4Pc) and polycationic poly-lysine. The fluorescence of AlC4Pc, with the maximum excitation and emission wavelengths at 620 and 701 nm, respectively, was quenched by poly-lysine with a proper concentration, but recovered by adding nucleic acids. Under optimal conditions, the recovered fluorescence was in proportional to the concentration of nucleic acids. The linear ranges of the calibration curves were 5-200 ng mL−1 for both calf thymus DNA (ctDNA) and fish sperm DNA (fsDNA) with the detection limit of 2.6 ng mL−1 for ctDNA and 2.1 ng mL−1 for fsDNA. The relative standard deviation (n = 6) was 1.9 and 1.3% for 50 ng mL−1 ctDNA and fsDNA, respectively. The proposed method was applied to the determination of nucleic acids in synthetic samples with satisfactory results.