Investigation of DNA Pesticide Interactions by Sensitive Electrochemiluminescence Method

Abstract

A solid-state [Ru(bpy)₂(dppz)]²⁺ (bpy = 2,2′-bipyridine, dppz = dipyrido[3,2-a: 2′,3′-c]phenazine) electrochemiluminescence (ECL) biosensor for studying the binding interactions between pesticides of heterocyclic polycyclic aromatic hydrocarbon (heteroPAH) and natural double-stranded DNA (ds-DNA) was constructed. Layer-by-layer films of negatively charged natural ds-DNA and polycationic poly (diallyldimethylammonium chloride) (PDDA) were assembled on the surface of a glassy carbon electrode (GCE). The complex of [Ru(bpy)₂(dppz)]²⁺ was used as a probe. Tripropylamine (TPA) was used as an electron donor to chemically amplify the ECL intensity of the probe. If the xenobiotic molecules compete with the probe for the same site on the DNA film, it would displace the probe from the DNA to decrease the ECL signal. The interactions of DNA with three pesticide molecules, quinalphos, quinclorac and carbendazim, were studied. From the displacement curve, the values of binding constant K _b of three pesticides to DNA is determined, which is in the range of 0.5 × 10⁴ to 2.3 × 10⁴ M⁻¹.

Keywords:

• Binding constant
• DNA biosensor
• Electrochemiluminescence
• Pesticides

Acknowledgments

The authors thank the financial support from the Key Program of Science and Technology of Beijing Municipal Education Commission (No. KZ201110005006), the Beijing Natural Science Foundation (No. 8102009), and Beijing Municipal Institution of Higher Learning Academic Innovating Group Projects (No. PHR 201007105).

Notes

^a Average values of three measurements.