Using external stimuli to design responsive supramolecular systems with predictable properties

Bianco, Simona (2025) Using external stimuli to design responsive supramolecular systems with predictable properties. PhD thesis, University of Glasgow.

Abstract

Supramolecular gels formed by the self-assembly of peptide-based LMWG are a class of soft materials that have attracted significant interest for a vast range of applications. Due to the non-covalent nature of the interactions underpinning the gel networks, these materials can exhibit stimuli-responsive behaviour to external triggers. By introducing this aspect in their design, a wide variety of new materials can be accessed with pre-determined properties with a high level of temporal and spatial control. In this Thesis, we describe how to harness external stimuli to induce predictable and reversible changes in supramolecular systems, achieving materials with desirable properties for different potential applications.

First, we show a dipeptide-based LMWG system undergoing pre-programmable gel-to-sol-to-gel transitions obtained by means of a pH cycle. We investigate the effect of mechanical stimuli applied during rheological measurements on the properties of these evolving materials, highlighting how varying parameters of strain and frequency can be used to obtain a wide range of gels with different properties starting from the same material. Building on these results, we then design a new system undergoing gel-to-sol-to-gel transitions capable of aligning under unidirectional shear in the solution phase. Using a novel combined technique of rheology, polarised light imaging and SAXS, we show the potential of this system to prepare gels with aligned domains using mechanical stimuli. We further highlight the versatility of this approach by inducing alignment using a magnetic field.

We then describe the use of a non-invasive light trigger to design a multicomponent system based on a LMWG and a photoacid molecule capable of switching pH under irradiation. We show how this approach yields a light-responsive system that reproducibly changes viscosity under irradiation. Using a variety of combined in situ techniques (rheology, NMR and SAXS), we elucidate the way these changes occur on a variety of length scales. We finally show how this stimuli-responsive system can be used to stop flow at specific locations using light and discuss potential applications.

Finally, we focus on the design of peptide-based gels for applications in drug storage and release by taking advantage of their unique response to mechanical stimulus. By using rheology, SAXS and release tests we show how gel mechanical properties, network morphology and choice of trigger can affect the ability of these systems to store and successfully release a cargo molecule. Based on this, we then establish a novel method to release biologics using a simple mechanical stimulus. Lastly, we test the stability of these systems under various real-world conditions for future applications in drug delivery.

• Item Type: Thesis (PhD)
• Qualification Level: Doctoral
• Subjects: Q Science > QD Chemistry
• Colleges/Schools: College of Science and Engineering > School of Chemistry
• Supervisor's Name: Adams, Professor Dave
• Date of Award: 2025
• Depositing User: Theses Team
• Unique ID: glathesis:2025-85169
• Copyright: Copyright of this thesis is held by the author.
• Date Deposited: 10 Jun 2025 13:54
• Last Modified: 10 Jun 2025 13:57
• Thesis DOI: 10.5525/gla.thesis.85169
• URI: https://theses.gla.ac.uk/id/eprint/85169

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