Fusing synthetic biology with nanotechnology: Integrating proteins into carbon nanotube field-effect transistors

Gwyther, Rebecca 2023. Fusing synthetic biology with nanotechnology: Integrating proteins into carbon nanotube field-effect transistors. PhD Thesis, Cardiff University. Item availability restricted.

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Abstract

Proteins are nature’s own nanomachines. Crafted through years of evolution, they are optimised to perform a range of cellular functions. To translate this into a useful nanotechnological application, proteins can be integrated into fundamental electronic devices known as carbon nanotube field-effect transistors (NT-FETs). I do this by engineering in non-natural amino acid p-azido-L-phenylalanine (AzF), which can be activated by UV light to covalently bind the carbon nanotube channel of an NT-FET. This creates an intimate environment for signal transduction, whereby an external biochemical signal (e.g., a chemical reaction, or incoming charge density from a protein-protein interaction) is transduced into an electrical signal. Potential applications for this will be dependent on the protein interfaced, but this thesis will consider two key themes: biosensing and optoelectronic gating. Chapter 3 builds on previous research by the Jones and Palma collaboration to develop a biosensor for antibiotic resistance (ABR). I do this by covalently integrating BLIP-II (Beta-Lactamase Inhibitory Protein II) to an NT-FET, transducing binding events with ABR biomarkers, the class A β-lactamases. NT-FETs were functionalised with defined BLIP-IIAzF variants to sample different orientations of analytes TEM-1 and KPC-2 β-lactamase. The distinct electrical signals generated correlated to the unique electrostatic surface being sampled, providing evidence for electrostatic gating. Chapter 4 builds on the experimental results from Chapter 3 to consider whether the BLIP-IIAzF—NT-FET interface can be effectively modelled to predict AzF mutation site success in mediating proximal analyte sensing. Using molecular dynamics, data on AzF side chain rotamer propensity was extracted, and in silico modelling was performed to assess the possible binding orientations of BLIP-IIAzF variants at the NT-FET interface. Distance and electrostatic potential of incoming β-lactamases were measured and showed correlation to the electrostatic gating observed in Chapter 3. Chapter 5 was devised in collaboration with the Bobrinetskiy lab, as I looked to exploit nature’s own light-responsive elements by covalently integrating sfGFP (superfolder Green Fluorescent Protein) into an NT-FET platform. By defining sfGFP orientation through two distinct AzF anchor sites, light was shown to induce optoelectronic memory and optoelectronic gating. Further novelty was discovered as water regenerated the optoelectronic gating response after six months of protein dehydration.

Item Type:	Thesis (PhD)
Date Type:	Completion
Status:	Unpublished
Schools:	Biosciences
Subjects:	Q Science > Q Science (General)
Date of First Compliant Deposit:	31 August 2023
Last Modified:	01 Sep 2023 13:18
URI:	https://orca.cardiff.ac.uk/id/eprint/162123

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