Magnetic Characteristics of Copper Ion-Modified DNA Thin Films

Abstract

We developed a new method of fabricating a divalent copper ion (Cu2+) modified DNA thin film on a glass substrate and studied its magnetic properties. We evaluated the coercive field (Hc), remanent magnetization (Mr), susceptibility (χ), and thermal variation of magnetization with varying Cu2+ concentrations [Cu2+] resulting in DNA thin films. Although thickness of the two dimensional DNA thin film with Cu2+ in dry state was extremely thin (0.6 nm), significant ferromagnetic signals were observed at room temperature. The DNA thin films with a [Cu2+] near 5 mM showed the distinct S-shape hysteresis with appreciable high Hc, Mr and χ at low field (≤600 Oe). These were primarily caused by the presence of small magnetic dipoles of Cu2+ coordination on the DNA molecule, through unpaired d electrons interacting with their nearest neighbors and the inter-exchange energy in the magnetic dipoles making other neighboring dipoles oriented in the same direction.

Coverage percentage and raman measurement of cross-tile and scaffold cross-tile based DNA nanostructures

“…The ions were added to the DNA sample solution after completing the DNA hybridization in order to avoid the structural deformation of the DNA nanolattices due to the presence of ions at a relatively higher concentration than the optimum ion-doping concentration due to the presence of excess ions (up to an optimum ion-doping concentration, DNA lattice periodicities were observable and above, DNA lattice were not formed properly so that lattice periodicities were hardly observable). A stepwise addition of the ions into the DNA samples revealed that the optimum ion doping concentrations for the DNA nanolattices were of 2 mM for Ni 2+ and 1 mM for Dy 3+ [23][24][25].…”

Diluted Magnetic DNA Nanowires

“…The dopant ions are distributed to DNA almost randomly assuming that the binding probabilities of the dopant to G-C, A-T and (PO 4 ) − are similar (33%) in contrast to Dugasani et al [19].…”

“…Doping process is required to start after the successful finish of former work. Dugasani et al [19] suggested the most probable locations of subsequent dopant ions between base pairs and PO4, and at last, the random displacement of dopants instead of hydrogen atoms of N-H-N and N-H-O.…”

“…There are probable positions where dopant ions will be located. It is thought that unbounded oxygen of phosphate holds on to the dopant ion according to Dugasani et al [19]. Other transition metals (Mn, Fe, Co, Ni and Cu) can be doped to DNA, and they can show ferromagnetic behaviour [19,26].…”

“…Computational models are properly developed to investigate the electrical conduction in DNA nanowires by Panahi and Chitsazanmoghaddam [17] and Behnia and Fathizadeh [18]. The studies performed by Dugasani et al [19] and Nikiforov et al [20] discovered that divalent metal ion-doped DNA exhibits soft ferromagnetic (FM) behaviour. Both of the studies claim that the origin of the soft ferromagnetic behaviour is the interaction between doped ions.…”