Nano-assemblies of cyclodextrin complexes at oil-water interfaces as sustainable alternatives to surfactants

Cyclodextrins (CDs), cyclic oligosaccharides known for their amphiphilic cavity, have emerged as promising agents for stabilising oil-water interfaces through the formation of supramolecular complexes. This project aims to investigate the formation and structural characteristics of interfacial films created by cyclodextrin-oil complexes and to correlate these properties with the stability of emulsions. In particular, the influence of small amount of oil molecules forming high strength complexes with CDs within a mixture of oils forming the non-polar phase will be explored.<br /> <br /> The central hypothesis is that CDs can form robust, structured interfacial films via host-guest interactions with targeted hydrophobic molecules in the oil phase, which can provide a versatile method to build strong interfacial films for a very broad range of oil mixtures, thereby enhancing emulsion stability for CDs-stabilised systems and providing robust alternatives to surfactant-stabilised emulsions. Using model oil-water systems, interfacial films will be formed and characterised through interfacial rheology, confocal laser scanning microscopy (CLSM) and atomic force microscopy (AFM). Coalescence events between two oil droplets suspended in CD solutions will also be examined with high speed recording to relate the kinetics of coalescence to the film structures built on these droplets using a range of conditions relevant to the emulsion studies below. Complementary techniques such as small-angle neutron scattering (SANS) and cryo-electron microscopy will also be employed to elucidate the nanoscale architecture of the films.<br /> <br /> Emulsion stability will be assessed under varying conditions of pH, ionic strength, and temperature to simulate real-world applications. The relationship between film structure, such as thickness, elasticity, molecular organisation and emulsion stability metrics (e.g., droplet size distribution, coalescence rate) will be systematically analysed.<br /> <br /> This research will contribute to the fundamental understanding of cyclodextrin-mediated interfacial phenomena and offer insights into designing novel, biocompatible emulsifiers for applications in foods, pharmaceuticals, and cosmetics. By bridging molecular-scale interactions with macroscopic emulsion behaviour, the project seeks to establish design principles for next-generation stabilisers based on cyclodextrin chemistry.<br />

<p>To investigate the structure and properties of cyclodextrin-stabilised interfacial films, a combination of complementary experimental techniques will be employed:</p> <ol> <li><strong>Pendant Drop Analysis and High-Speed Visualisation of Drop-Drop Coalescence</strong><br /> Pendant drop tensiometry will be used to assess interfacial tension changes induced by cyclodextrin complexation with the range of oils we intend to study. This is indicative of film formation. We will further probe the stability of these films with this method using an in-house modification of this method (now well-established in our research group) that allows us to record the coalescence of two droplets coated with the CD-based films using a high-speed camera. The data from these videos will be processed and analysed with an image-processing software to extract coalescence kinetics and relate them to film structure.</li> <li><strong>Interfacial Rheology</strong><br /> Interfacial shear and dilatational rheology will be used to quantify the viscoelastic properties of the films. These measurements will provide insights into film strength, elasticity, and resistance to deformation, which are critical for emulsion stability.</li> <li><strong>Confocal Laser Scanning Microscopy (CLSM)</strong><br /> CLSM, combined with fluorescently labelled cyclodextrins or oil-phase markers, will allow visualisation of the film structure in situ at the oil-water interface. This technique will help assess film continuity and spatial distribution.</li> <li><strong>Atomic Force Microscopy (AFM)</strong><br /> AFM will be used to image the interfacial films at the nanoscale. By transferring the film onto a solid substrate via Langmuir-Blodgett deposition, topographical and mechanical mapping will reveal film thickness, roughness, and molecular organisation.</li> <li><strong>Cryogenic Electron Microscopy (Cryo-EM)</strong><br /> Cryo-EM will provide high-resolution images of the interfacial architecture in its native hydrated state, offering direct visual evidence of film morphology and any self-assembled structures.</li> <li><strong>Small-Angle Neutron Scattering (SANS)</strong><br /> We will apply to neutron facilities for time on SANS instrument, which will be employed to probe the internal structure and layering of the interfacial films at the nanometre scale. Contrast variation techniques will be used to selectively highlight cyclodextrin and oil components.</li> </ol>

<p>Formal applications for research degree study should be made online through the <a href="https://www.leeds.ac.uk/research-applying/doc/applying-research-degrees">University's website</a>. Please state clearly in Planned Course of Study section that you are applying for <em><strong>EPSRC DTP Engineering & Physical Sciences,</strong></em> in the research information section that the research degree you wish to be considered for is <em><strong>Nano-assemblies of cyclodextrin complexes at oil-water interfaces as sustainable alternatives to surfactants </strong></em>as well as <a href="https://eps.leeds.ac.uk/chemical-engineering/staff/415/dr-olivier-cayre">Dr Olivier Cayre</a> as your proposed supervisor and in the finance section, please state clearly <em><strong>the funding that you are applying for, if you are self-funding or externally sponsored</strong></em>.</p> <p>Applications will be considered after the closing date of 30 January 2026.  Potential applicants are strongly encouraged to contact the supervisors for an informal discussion before making a formal application.  We also advise that you apply at the earliest opportunity as the application and selection process may close early, should we receive a sufficient number of applications or that a suitable candidate is appointed.</p> <p>Please note that you must provide the following documents in support of your application by the closing date of Friday 30 January 2026:</p> <ul> <li>Full Transcripts of all degree study or if in final year of study, full transcripts to date including the grading scheme</li> <li>Personal Statement outlining your interest in the project</li> <li>CV</li> </ul> <p><em>As an international research-intensive university, we welcome students from all walks of life and from across the world. We foster an inclusive environment where all can flourish and prosper, and we are proud of our strong commitment to student education. Across all Faculties we are dedicated to diversifying our community and we welcome the unique contributions that individuals can bring, and particularly encourage applications from, but not limited to Black, Asian, people who belong to a minority ethnic community, people who identify as LGBT+ and people with disabilities. Applicants will always be selected based on merit and ability.</em></p>

Applicants to research degree programmes should normally have at least a first class or an upper second class British Bachelors Honours degree (or equivalent) in an appropriate discipline. The criteria for entry for some research degrees may be higher, for example, several faculties, also require a Masters degree. Applicants are advised to check with the relevant School prior to making an application. Applicants who are uncertain about the requirements for a particular research degree are advised to contact the School or Graduate School prior to making an application.

The minimum English language entry requirement for research postgraduate research study is an IELTS of 6.0 overall with at least 5.5 in each component (reading, writing, listening and speaking) or equivalent. The test must be dated within two years of the start date of the course in order to be valid. Some schools and faculties have a higher requirement.

<p class="MsoNoSpacing">A highly competitive EPSRC Doctoral Landscape Award in collaboration with Givaudan, providing full academic fees, together with a tax-free maintenance grant at the standard UKRI rate (£20,780 in academic session 2025/26) for 3.5 years.  Training and support will also be provided.<br /> <br /> This opportunity is open to UK applicants only.  All candidates will be placed into the EPSRC Doctoral Landscape Award Competition and selection is based on academic merit.</p> <p>Please note that there is only 2 funded places available to UK applicants only and this project is in competition with at least 2 other projects to secure this funding.  If you are successful in securing an academic offer for PhD study, this does not mean that you have been successful in securing an offer of funding.</p> <p>Please refer to the <a href="https://www.ukcisa.org.uk/">UKCISA</a> website for information regarding Fee Status for Non-UK Nationals.</p>

<p>For further information about this project, please contact Dr Olivier Cayre by email to <a href="mailto:O.J.Cayre@leeds.ac.uk">O.J.Cayre@leeds.ac.uk</a></p> <p>For further information about your application, please contact PGR Admissions by email to <a href="mailto:phd@engineering.leeds.ac.uk">phd@engineering.leeds.ac.uk</a></p>