Ultra-sensitive Tb3+/G-quadruplex fluorescence detection of oxidative DNA damage coupled with DNA glycosylase

Development of simple, sensitive and rapid sensing strategy for DNA damage induced by chemical reagents is urgent demand. In this assay, a Tb 3+ /G-quadruplex fluorescence system was proposed for the sensitive detection of DNA damage induced by Fenton reaction. The specific guanine-rich oligonucleotides can form G-quadruplex induced by Tb 3+ , leading to an enhancement of Tb 3+ emission due to energy transfer from guanine to Tb 3+ . After a DNA damage reaction with Fenton reagents, an obvious fluorescence decrease was observed due to the structure change of Tb 3+ /G-quadruplex. which was also confirmed by polyacrylamide gel electrophoresis and circular dichroism. The Fe 2+ -mediated Fenton reaction with as low as 0.01 μM Fe 2+ and 0.04 μM H 2 O 2 induced oxidative DNA damage can be detected. Additionally, the human 8-oxoguanine DNA glycosylase (hOGG 1) was introduced to amplify DNA oxidation damage, by converting DNA oxidative nucleobases to strand break. Over 30-fold lower detection limit of 0.3 nM Fe 2+ and 1.2 nM H 2 O 2 was achieved. Alternative specific DNA damage or other DNA repair enzymes produced much less fluorescence decrease, demonstrating its good selectivity. It shows the potential to become a universal screening tool for the rapid and sensitive assessment of the genotoxicity of the overwhelming number of chemicals in environment.