Development and applications of novel nanostructures from graphene and viral building blocks

Stokes, Kate ORCID: 0009-0003-6045-0994 (2025). Development and applications of novel nanostructures from graphene and viral building blocks. University of Birmingham. Eng.D.

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Abstract

GraPhage13 aerogels (GPA) are porous, ultra-low density nanocomposites fabricated through the self-assembly of graphene oxide (GO), a monolayer of carbon atoms with various oxygen-containing functional groups, and the filamentous bacteriophage M13. The cost-effective, scalable, and environmentally friendly production of GPA, combined with the ability to customise its properties through the functionalisation of GO and chemical and genetic modification of M13, makes GPA a highly promising material across a diverse range of industries, including healthcare, defence, and environmental monitoring.

This thesis presents a comprehensive investigation into GPA, focusing on the optimal chemical environment for its formation, the mechanism of its self-assembly, and its physical characterisation. A wide range of experimental techniques were employed, including microscopy and spectroscopy methods such as scanning electron microscopy (SEM), atomic force microscopy (AFM), Raman spectroscopy, ultraviolet-visible (UV-Vis) spectroscopy, and energy-dispersive X-ray (EDX) spectroscopy. Additional techniques included titrations, zeta potential analysis, dynamic vapour
sorption (DVS), and electrical conductivity measurements. The resulting data were analysed using kinetic modelling, peak fitting, image analysis, and statistical evaluation, including the use of the Bayesian Information Criterion (BIC) to assess model accuracy.

Interactions between GO and M13 were found to be pH-dependent. In the range of pH 2–6, electrostatic repulsion is minimised, enabling their aggregation. The optimal GPA was generated by combining GO and M13 at pH 4.9. At lower pH values, M13 tends to independently precipitate or suffer structural damage, while the increased electrostatic repulsion towards pH 6 reduces the probability of aggregation.

Examining its thermal properties, GPA demonstrated progressive structural changes upon heating, including partial reduction of GO, a decrease in stiffness, increased structural disorder, and the formation of fewer but larger pores.

Thermal characterisation revealed progressive structural changes with heating, including partial reduction of GO, decreased stiffness, increased disorder, and the formation of fewer but larger pores. GPA also demonstrated high hygroscopicity, with a water sorption capacity of 0.68 ± 0.02 g/g at 90% relative humidity, exhibiting stable and reversible behaviour. Ethanol uptake outperformed similar carbon-based materials, and although acetone uptake was lower, there is potential to improve and tune its sorption capacity for specific analytes through the functionalisation of GO and M13.

The electrical properties of GPA revealed its inherently insulating nature, with a low conductivity of 6.8 nS/cm. However, this was significantly enhanced through the incorporation of gold nanoparticles (AuNPs), increasing to 190 nS/cm with 20 nm AuNPs and up to 360 nS/cm with 5 nm AuNPs.

Together, these findings lay a foundation for the integration of GPA into graphene-based devices. The tuneability and multifunctionality of GPA highlight its potential in applications such as chemical sensors, adsorbents, and energy storage systems.

Type of Work:

Thesis (Doctorates > Eng.D.)

Award Type:

Doctorates > Eng.D.

Supervisor(s):