In this work, we
demonstrate chiral-induced spin selectivity (CISS)-based
label-free electrochemical impedimetric detection of radiation-induced
DNA damage using the electrons’ spin as a novel tool of sensing.
For this, self-assembled monolayers (SAMs) of short ds-DNA (of length
7.14 nm) are prepared on arrays of multilayer thin film devices comprising
a gold overlay (500 μm diameter with 10 nm thickness) on a nickel
thin film (100 nm) fabricated by the physical vapor deposition technique.
Subsequently, the SAMs of ds-DNA are exposed to ultraviolet C (UVC)
radiation for a prolonged period of 8 h to induce structural perturbations
in DNA. The susceptibility of DNA to radiation-induced damage was
probed by recording the spin-dependent electrochemical impedimetric
spectra, wherein a continuous sinusoidal wave of the amplitude of
10 mV was superimposed on DC bias in the frequency range of 100–105 Hz, with simultaneous spin injection
through the attached DNA. The inherent correlation between the charge-transfer
resistance (R
ct) and the spin selectivity
of electrons through DNA was taken into account for the detection
of DNA damage for the first time with a limit of detection achieved
up to 10 picomolar concentrations of DNA. As the spin-polarized electrons
directly probe the structural symmetry, it is robust against perturbation
from electronic signals usually found in conventional electrochemical
biosensors.