Recognition and Determination of DNA Using Victoria Blue B as Electrochemical Probe

The recognition of Victoria blue B (VBB) with DNA was investigated by electrochemical and spectrophotometric method in pH 5.0 B-R buffer solution. In the potential scan range of +0.70~+1.30 V (vs. SCE), VBB had an irreversible oxidative peak at +0.984 V at the scan rate of 100.0 mV/s on cyclic voltammogram. After the addition of double-stranded DNA (dsDNA) or single-stranded DNA (ssDNA) into VBB solution, the peak current decreased significantly and the peak potential shifted negatively. The results demonstrated that VBB binding to DNA was caused by electrostatic interaction. The binding of VBB with dsDNA was stronger than that with ssDNA. By virtue of this difference, VBB can be used as an electrochemical probe to identify ssDNA and dsDNA. The electrochemical behaviours of the VBB in the presence and absence of DNA was carefully studied. Electrochemical parameters such as the diffusion coefficient (D), the electron transfer coefficient (α) and the electrochemical reaction standard rate constant (ks') were calculated. The binding ratio (m) and the binding constant (β) of VBB to dsDNA were further investigated by voltammetric method. UV-Vis spectrophotometry also proved that VBB bound to DNA mainly through electrostatic mode. Based on the decrease of the differential pulse voltammetric peak current of VBB with the increase of dsDNA concentration, a working curve was constructed for dsDNA in the range of 0.10~8.0 mg/L with the linear regression equation as Δip(10-6A)=0.072C(mg/L)+0.24 and the detection limit (3σ) as 0.069 mg/L. The method was satisfactorily applied to the determination of the DNA content in the artifical samples.