Electrochemical detection of DNA based on its interaction with safranine T

Abstract

A second order derivative linear sweep voltammetric method was established for the determination of microamount of DNA based on its interaction with safranine T (ST). In pH 6.0 Britton-Robinson (B-R) buffer solution ST had a sensitive second order derivative linear sweep voltammetric reductive peak at -0.43 V (vs SCE). The addition of DNA into ST solution resulted in the decrease of peak current and negative movement of peak potential, which were the typical characteristics of electrostatic attraction of small molecule with DNA. The conditions of the binding reaction and the electrochemical detection were carefully studied. The influences of coexisting substances and ionic strength on the interaction were investigated. Under the selected conditions, the decrease of peak current was linear with DNA concentration in the range of 1.0∼12.0 mg/L with the linear regression equation as ΔIp(nA) = 58.96C (μg/mL) - 48.63 (n = 9, γ = 0.993) and the detection limit as 0.79 μg/mL (3σ). Four synthetic samples were determined with satisfactory results and the recovery was in the range of 96.7 to 106.7%. The stoichiometry of the complex was calculated by the voltammetric method with the binding ratio as 1: 2 and the binding constant as 1.0 x 10 7 .