Quantum mechanical tunnelling probe for next-generation single molecule sensor
File(s)
Author(s)
Yi, Long
Type
Thesis
Abstract
Among Single-molecule detection techniques, quantum mechanical tunnelling (QMT) based sensors demonstrated outstanding performance in studying single molecules due to their remarkable spatial resolution, high sensitivity and selectivity. QMT-based sensor requires two nanoelectrodes separated by a sub-5 nm gap, which is the main obstacle in fabrication and limits the technique for wide application. To address this challenge, the work reported a new robust fabrication protocol on dual-barrel nanoprobe and discovered further single-molecule detection applications.
In this thesis, a robust fabrication protocol of QMT probes is introduced. The QMT probe is fabricated on dual-barrel carbon nanoelectrodes through electrodeposition. This method marks a significant advancement in developing a new QMT platform.
Then, several analytes are investigated using the QMT probe to study single-molecule behaviours. Firstly, it is demonstrated that the redox cycling occurs on QMT probes, resulting in observable changes in current amplitude. The surface modification of aptamer that can bind with target protein, shielding in redox reagents within the tunnelling regime and act as an electrochemical sensor.
In addition, non-redox active gold nanoparticles can be detected on QMT probes, and the collision and adsorption of these nanoparticles can be directly observed in real-time current-time measurements. Redox-active silver nanoparticles and nanocluster collisions caused by the oxidation of Ag nanoparticles can also be followed on QMT probes.
Furthermore, The QMT probes can detect double-strand DNA, nucleotides and protein through diffusion in and out of the tunnelling junction, leading to tunnelling current transients in the current-time (I-t) response with high sensitivity and selectivity. Additionally, QMT probes functionalised with biotin can bind with streptavidin tetramers, forming biotin-streptavidin molecular junctions. This enables the direct observation of protein behaviours through real-time tunnelling current readouts by applying a voltage bias between the tunnelling junctions.
In this thesis, a robust fabrication protocol of QMT probes is introduced. The QMT probe is fabricated on dual-barrel carbon nanoelectrodes through electrodeposition. This method marks a significant advancement in developing a new QMT platform.
Then, several analytes are investigated using the QMT probe to study single-molecule behaviours. Firstly, it is demonstrated that the redox cycling occurs on QMT probes, resulting in observable changes in current amplitude. The surface modification of aptamer that can bind with target protein, shielding in redox reagents within the tunnelling regime and act as an electrochemical sensor.
In addition, non-redox active gold nanoparticles can be detected on QMT probes, and the collision and adsorption of these nanoparticles can be directly observed in real-time current-time measurements. Redox-active silver nanoparticles and nanocluster collisions caused by the oxidation of Ag nanoparticles can also be followed on QMT probes.
Furthermore, The QMT probes can detect double-strand DNA, nucleotides and protein through diffusion in and out of the tunnelling junction, leading to tunnelling current transients in the current-time (I-t) response with high sensitivity and selectivity. Additionally, QMT probes functionalised with biotin can bind with streptavidin tetramers, forming biotin-streptavidin molecular junctions. This enables the direct observation of protein behaviours through real-time tunnelling current readouts by applying a voltage bias between the tunnelling junctions.
Version
Open Access
Date Issued
2023-12-11
Date Awarded
2024-05-01
Copyright Statement
Creative Commons Attribution NonCommercial NoDerivatives Licence
Advisor
Edel, Joshua
Ivanov, Aleksandar
Publisher Department
Chemistry
Publisher Institution
Imperial College London
Qualification Level
Doctoral
Qualification Name
Doctor of Philosophy (PhD)