Voltammetric determination of DNA based on its interaction with neutral red

Abstract

A new linear sweep voltammetric (LSV) assay of fsDNA based on its interaction with neutral red (NR) is presented. At <i>p</i>H 8.0 Britton-Robinson (B-R) buffer solution, the dye can bind with DNA to form a supramolecular complex, which results in the decrease of the linear sweep voltammetric reductive peak current at -0.60 V (vs. SCE) on the mercury electrode. The binding reaction is completed within 20 min at room temperature and remains stable for at least 2 hours. The optimal conditions for the binding reaction and the electrochemical detection have been determined. Under the optimal conditions there is little interference from most metal ions and amino acids. The calibration graph for fsDNA is linear in the range of 1.0~30.0 mg/L with the linear regression equation as Δ<i>l</i>_pʹʹ(nA)=28.20C (mg/ L)+ 10.84 (n=9, γ=0.992) and the detection limit as 0.67 mg/L. The interaction mechanism is characterized by the aggregation of DNA-NR supramolecular complex by UV-vis absorption spectrophotometry and cyclic voltammetry. The stoichiometry of this supramolecular complex has been calculated with the binding number as 1.5 and the binding constant as

1.73×10⁷