Abstract
Stability of the DNA molecule is essential for the proper functioning and sustainability of all living organisms. In this study, we investigate the effect of gamma radiation (γ-radiation) on spin-selective electron transfer through double strand (ds)DNA molecules. Self-assembled monolayers (SAMs) of 21-base long DNA are prepared on Au-coated Ni thin film. We measure the spin polarization (%) of the SAMs of ds-DNA using the spin-dependent electrochemical technique. We use a Cs-based γ-radiation source to expose the SAMs of ds-DNA immobilized on thin films for various time intervals ranging from 0–30 min. The susceptibility of DNA to γ-radiation is measured by spin-dependent electrochemistry. We observe that the efficiency of spin filtering by ds-DNA gradually decreases when exposure (to γ-radiation) time increases, and drops below 1% after 30 min of exposure. The change in spin polarization value is related either to the conformational perturbation in DNA or to structural damage in DNA molecules caused by ionizing radiation.
Highlights
DNA is a genetic material and is crucial to the smooth functioning of all living creatures
In the special case of chiral molecules, it has been demonstrated, experimentally and theoretically, by the Ron Naaman group and others, that the spin-selective electron transfer occurs in a variety of biomolecules, and the phenomenon is popularly known as chiral-induced spin selectivity (CISS) effect which has many implications, including bio-recognition, enantioselection and spin-specific chemical reactions [12,13,14,15]
The crystal structure of the surface of the Ni/Au film wa Figure 1a shows a schematic diagram of the side view of Ni/Au thin film on the diffraction (XRD), theofcorresponding pattern is by shown crystaland structure the surface of the Ni/Au film was probed
Summary
Ni/Au thinthin film (Side view) on the ds-DNA monolayer on Ni/Au thin film. SiO2/S pattern, (c) atomic force microscope (AFM) image of bare Ni/Au thin film, and ds-DNA monolayer on thin film.38.1◦ , 44.3◦ , and 64.5◦ represent (111), Planes corresponding to Ni/Au. The SAMs of ds-DNA on the Ni/Au surface and Pt wire were taken as the working and counter electrodes, respectively. In the forward scan of the current, at a particular voltage of 0.09 V, an oxidation peak appears due to the oxidation of Fe2+ species present in the solution. In this process, Fe2+ loses an electron, which subsequently passes through the interface of the SAMs of DNA to the working electrode. Note that a freshly prepared sample was taken each time for radiation exposure with the similar setup, and the spin polarization was calculated following the procedure described above.
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