Fiber optic biosensor for detection of DNA damage

This paper describes a fiber optic biosensor for the rapid and sensitive detection of radiationinduced or chemically-induced oxidative DNA damage. The assay is based on the hybridization and temperature-induced dissociation (melting curves) of synthetic oligonucleotides. The hybridization pair consists of a biotin labeled 38 mer oligonucleotide immobilized to a streptavidin-coated optical fiber and a fluorescently-labeled nearcomplementary (two base mismatch) oligonucleotide reporter sequence. The hybridizationbased assay detected 50nM labeled probe and could be run up to 10 times on the same fiber. Melting profiles were sensitive to high energy radiation and to 3-morpholinosydnonimine (SIN-1)-generated reactive decomposition products. The dynamic range of the assay for ionizing radiation extends from 20 to 1000cGy. Oxidative damage induced by SIN-1 was measured over a concentration range of 250µM to 3 mM.