Determination of Nucleic Acids on the Basis of Enhancement Effect of Resonance Light Scattering of Toluidine Blue

Abstract

Based on a detailed study of the interaction of toluidine blue (TB) with nucleic acids, a novel resonance light scattering (RLS) method was developed for the determination of nucleic acids. The RLS intensity of TB at 400 nm was greatly enhanced in the presence of nucleic acids at pH 3.17. Linear relationships between the enhanced RLS intensity and the concentration of nucleic acids were observed in the range of 0.0–2.7 µg cm−3 for calf thymus DNA (ctDNA), 0.0–2.2 µg cm−3 for fish sperm DNA (fsDNA), and 0.0–0.5 µg cm−3 for yeast RNA (yRNA), respectively. The limits of detection (3σ) were determined to be 24.0 ng cm−3 for ctDNA, 22.7 ng cm−3 for fsDNA and 5.1 ng cm−3 for yRNA. The binding constants were evaluated to be 1.1 × 104 dm3 mol−1 for ctDNA, 1.8 × 104 dm3 mol−1 for fsDNA, and 1.7 × 104 dm3 mol−1 for yRNA. The maximum binding numbers (n) were 2.7, 5.5, and 15.0 for ctDNA, fsDNA and yRNA, respectively. The proposed method was applied for determination of the nucleic acids in chicken blood. The analytical results obtained by the present method were in good with that from a UV method.