Andrea Hájková

Electrochemical DNA biosensor for detection of DNA damage induced by hydroxyl radicals

A simple electrochemical DNA biosensor based on a glassy carbon electrode (GCE) was prepared by adsorbing double-stranded DNA (dsDNA) onto the GCE surface and subsequently used for the detection of dsDNA damage induced by hydroxyl radicals. Investigation of the mutual interaction between hydroxyl radicals and dsDNA was conducted using a combination of several electrochemical detection techniques: square-wave voltammetry for direct monitoring the oxidation of dsDNA bases, and cyclic voltammetry and electrochemical impedance spectroscopy as indirect electrochemical methods making use of the redox-active indicator [Fe(CN)6]4-/3-. Hydroxyl radicals were generated electrochemically on the surface of a boron-doped diamond electrode and chemically (via the Fentons reaction or the auto-oxidation of Fe(II)). The extent of dsDNA damage by electrochemically generated hydroxyl radicals depended on the current density applied to the generating electrode: by applying 5, 10, and 50mAcm-2, selected relative biosensor responses decreased after 3min incubation from 100% to 38%, 27%, and 3%, respectively. Chemically generated hydroxyl radicals caused less pronounced dsDNA damage, and their damaging activity depended on the form of Fe(II) ions: decreases to 49% (Fentons reaction; Fe(II) complexed with EDTA) and 33% (auto-oxidation of Fe(II); Fe(II) complexed with dsDNA) were observed after 10min incubation.

Novel Electrochemical DNA Biosensors as Tools for Investigation and Detection of DNA Damage

Supramolecular interactions of various organic xenobiotic compounds with deoxyribonucleic acid (DNA) are among the most important aspects of biological studies in clinical analysis, drug discovery, and pharmaceutical development processes. In recent years, there has been a growing interest in the electrochemical investigation of interactions between a studied analyte and DNA. Observing the pre- and post-electrochemical signals of DNA or monitoring its interaction with xenobiotics provides good evidence for the interaction mechanism to be elucidated. Such interaction can also be used for sensitive determination of these compounds. This short review summarizes our results obtained during the last 5 years in the field of novel electrochemical DNA biosensors utilizing carbon-based transducers as substrates for immobilization of DNA. It should provide evidence that the electrochemical approach (employing simple, fast, sensitive, and inexpensive DNA biosensors as tools for investigation and detection of DNA damage) brings new insight into human health protection or rational drug design and leads to further understanding of the interaction mechanism between xenobiotic compounds and DNA.