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Article

Voltammetric Sensor for Oxidized DNA Using Ultrathin Films of Osmium and Ruthenium Metallopolymers

Supporting Info

Amos Mugweru,^† Bingquan Wang,^† and James Rusling*^†^‡

Department of Chemistry, University of Connecticut, U-60, 55 North Eagleville Road, Storrs, Connecticut 06269-3060, and Department of Pharmacology, University of Connecticut Health Center, Farmington, Connecticut 06032

Anal. Chem., 2004, 76 (18), pp 5557–5563

DOI: 10.1021/ac049375j

Publication Date (Web): August 7, 2004

†

University of Connecticut.

To whom correspondence should be addressed. E-mail: James.Rusling@ uconn.edu.

‡

University of Connecticut Health Center.

Abstract

Films containing [Os(bpy)₂(PVP)₁₀Cl]⁺ and [Ru(bpy)₂(PVP)₁₀Cl]⁺ metallopolymers were assembled layer by layer on pyrolytic graphite electrodes to make sensors that selectively detect oxidized DNA. These films showed reversible, independent electrochemistry for electroactive Os³⁺/Os²⁺ and Ru³⁺/Ru²⁺ centers, with formal potentials of 0.34 and 0.76 V vs SCE, respectively. The combination of ruthenium and osmium metallopolymers in the films provided a catalytic Os square wave voltammetry (SWV) peak that is mainly selective for 8-oxoguanine and the detection of other oxidized nucleobases from the Ru peak. The method is applicable to measurements on DNA in solution or DNA incorporated into films. Using the Os SWV peak, 1 oxidized nucleobase in 6000 was detected. The sensor is simple and inexpensive, and the approach may be useful for the detection of oxidized DNA as a clinical biomarker for oxidative stress.