Label-free and ultrasensitive electrochemiluminescence detection of oxidative DNA damage using DNA repair enzyme

Abstract

Endogenous cell metabolism and chemical reactions can induce oxidative DNA damage, which is involved in the development of different diseases. In this work, a label-free electrochemiluminescence (ECL) assay was proposed for the sensitive detection of oxidative DNA damage in an assembled DNA film. We employed the formamidopyrimidine-DNA glycosylase (Fpg) to convert DNA oxidative nucleobases to strand break, allowing to detect the DNA damage inducing minimal change to the helical structure of DNA. A “light-switch” DNA intercalator, [Ru(bpy)2(dppz)]2+ (bpy = 2, 2′-bipyridine, dppz = dipyrido[3, 2-a:2′, 3′-c]phenazine) was introduced as an ECL signal reporter to detect the DNA strand breaks. The damaged DNA film on the reduced graphene oxide and gold nanoparticles (r-GO@Au) modified ITO electrode bound less ECL indicator than the intact film and accompanied by a drop in ECL intensity, which were also confirmed by gel electrophoresis and fluorescence measurements. As a result, a Fe2+-mediated Fenton reaction with as low as 10 nM Fe2+ and 40 nM H2O2 induced DNA damage can be detected, 100-fold lower than the concentration measured without Fpg. To demonstrate its universality, the successful detection of DNA damage induced by Rose Bengal under irradiation was also achieved. The proposed strategy shows its potential practicality for the sensitive and rapid assessment of the genotoxicity of environmental pollutants.