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. 2024 Sep 28;14(1):22405.
doi: 10.1038/s41598-024-74133-w.

Low bias charge transport in DNA

Maciej Wiesner #  1 , Jan Barciszewski #  2   3 , Agnieszka Belter #  3 , Andrzej Sierakowski  4 , Adrian Drzazga  5 , Marcin K Chmielewski  6   7
Affiliations

Low bias charge transport in DNA

Maciej Wiesner et al. Sci Rep. .

Abstract

The low-bias current-voltage technique was utilized to study charge transport in single-stranded DNA (ssDNA), assessing the method's effectiveness for future studies aimed at estimating the degree of mutation or DNA damage. In the paper, we showed that charge carrier transfer processes in ssDNA can be precisely monitored using low-bias currents. We used negative differential resistance and the Fowler-Nordheim model to differentiate the charge transport mechanisms observed in a device composed of gold electrode-thiol-ssDNA junctions. It was possible to distinguish the processes at the two junctions (Au/thiol and thiol/DNA) due to their distinct current-voltage characteristics. We observed positive charge carrier tunneling, which we attribute to oxidation and reduction processes in the nucleobases of the ssDNA. Our results suggest that even minor changes in DNA chains can be accurately detected using the described methodology.

Keywords: DNA; Differential resistance; Electron transport; Emission; Hole transport; Molecular junction; Tunneling.

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Conflict of interest statement

The authors declare no competing interests.

Figures

Fig. 1
Fig. 1
(a) A schematic of the ssDNA ligation procedure. (b) An SEM image showing Au/Ti electric contacts between which ssDNA was stretched. (c) AFM topography of ssDNA deposited on the surface of gold electrodes without forming a connection between the electrodes. (d) AFM topography of the ssDNA (red arrow) connecting both electrodes.
Fig. 2
Fig. 2
Results of measurements of (a) Rd vs. bias current; (b) gate voltage dependency of Rd; (c) voltage drop over the best sample as a function of bias current for several values of gate voltage (the inset shows gate voltage dependency of Umeas at I1); (d) dependencies of Umeas(Ug) at I = I1 (red triangles) and I2 (Ug) (black dots). Both dependencies were fitted with a linear function, and parameters are collected in Table 1.
Fig. 3
Fig. 3
Charge transport processes detected in the ssDNA and ssDNA/metal junction. (a) The red dashed line indicates the crossover between the Fowler-Nordheim and direct tunneling processes at Ug = 0 V. The green line represents the fitting to Eq. 2 with the following parameters: d = 30 Å, and φ = 0.16 eV. (b) Linear approximation of the threshold current dependence between FN and direct tunneling processes on gate voltage obtained for coefficients a = (-34 ± 2 )* 10−5 and b=(70 ± 0.12 )* mV.
Fig. 4
Fig. 4
Image of nanostructure of electric contacts prepared for deposition of ssDNA. Magnified central part of the nanostructure (marked by red circle) is showing in Fig. 1b.
Fig. 5
Fig. 5
Scheme of the measurement system.
See this image and copyright information in PMC

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