Simulation of quantum transport properties of a gold nanopore biosensor for DNA detection.

What is it about?

Quantum mechanical studies of the electronic transport properties of a memantine-functionalized gold nanopore biosensor for natural and mutated DNA nucleobase detection are reported. In this study, a gold electrode was functionalized with a modified diamondoid structure, called memantine, and the tunnelling current arising from nucleobases was investigated as it translated through the functionalized gold nanopore. Non-equilibrium Green's function (NEGF) and density functional theorem (DFT) methods have been used to analyze and calculate the results. The transmission spectrum for each nucleobase is presented. In order to justify that the resonance peaks are originating from the nucleobases, the Projected Densities of States (PDOS) of the nucleobases were plotted and compared with their corresponding transmission spectra. The electronic wave functions relating to transmission and the device sensitivity have also been shown. The proposed device is demonstrated to detect various natural and mutated nucleobases with a sensitivity ranging from 10^3 to 10^7. Finally, differential conductance methods have been found to be effective in detecting nucleobases in the case of overlapping transmission peaks.

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Why is it important?

In this report, the NEGF + DFT method is used to understand the fundamental working principles of a memantine functionalized gold electrode biosensor. The proposed device is demonstrated to detect various natural and mutated nucleobases. The sensitivity of the device spreads over the range of 10^3 to 10^7 for all the nucleobases. The transmission spectra for the nucleobases studied are shown and discussed. The observed resonant peaks are at least in the order of 0.3. The underlying physics behind these resonance peaks has been explained through calculating the projected densities of states of the nucleobases and concluding that these resonance peaks originate due to the translation of the nucleobases. The transmission pathways and electronic wave functions, which explain the coupling between the electrode and the molecules, are discussed. The MPSH calculated, in order to understand the energy levels of the nucleobases in the presence of electrodes, gives an excellent overview of the energy levels involved in the transmission resonance peaks for the nucleobases. The comparison between the various EWFs at a gate voltage of 1.27 V reveals the physics behind the excellent resolving and detecting capabilities of the device for various nucleobases. Finally, the differential conductances for various nucleobases were analyzed in order to resolve overlapping transmission spectra. This clearly shows the advantage of functionalizing both electrodes, which leaves less overlap of transmission spectra and gives more resolving capabilities to the device. It is confirmed that the proposed device can resolve the detection of a specific nucleobase with respect to other nucleobases.