Amplifying Quantum Tunneling Current Sensitivity through Labeling Nucleotides Using Graphene Nanogap Electrodes

Recent advances in cost-effective, ultra-rapid, and efficient DNA sequencing are in the saddle of the advancement of the personalization of medicines for understanding and early-stage detection of several killer diseases. Paying attention to a timely need for the development of solid-state nanodevices for rapid and controlled identification of DNA nucleotides, in this report, we theoretically explored the potential of labeling techniques in the sequencing of DNA nucleotides through solid-state graphene nanogap electrodes using the quantum tunneling current approach. Our study boasts the idea that labeling of DNA nucleotides can solve major hurdles of DNA sequencing, such as improving the signal-to-noise ratio, slowing down translocation velocity, and controlling orientational variations. Employing the first-principle density functional theory study, we identify unique interaction energy values for each labeled nucleotide having remarkable differences in the range of 0.10-0.74 eV. The zero-bias transmission spectra of the proposed setup suggest that the detection of the nucleotides is possible by applying very low gate voltages. Moreover, the labeling of nucleotides amplifies the conductance sensitivity considerably. I-V characteristics suggest that electrical recognition of each labeled nucleotide can be carried out at both lower (0.3 V) and higher (0.8 V) bias voltages with single-molecule resolution, although the maximum current sensitivity is observed at a higher bias voltage. The proposed sequencing device possesses high sensitivity and selectivity characteristics that are crucial for experimental purposes. We find that our results are rich compared to unlabeled nucleotides-based graphene nanopore/nanogap devices. Hence, the study will certainly motivate the experimentalists toward the application of a labeled DNA nucleotide system for ultra-rapid DNA sequencing by using the tunneling current approach.