An investigation into the aggregation of therapeutic peptides through adsorption to primary containers

Therapeutic peptides are highly functional drugs currently being investigated for a number of diseases, due to their naturally occurrence in the body, their targeted mechanism and efficacy and tolerability. The four therapeutic peptides under investigation in this thesis; glucagon, liraglutide, g797 and exendin-4 are all used or on trial for mediating blood glucose levels as a safe and effective treatment for type 2 diabetes. One of the largest drawbacks of peptides is their ability to aggregate and adsorb to surfaces that they come into contact with during their lifecycle; vials and syringes, causing loss of function, drug and toxicity. A large, underexplored area of drug related research is investigation into the interface; in part due to its complexity. A plethora of different methods were used in order to investigate the peptide solutions ability to aggregate and adsorb to surfaces. The initial step was to investigate the stability of the four therapeutic peptides in solution, providing information on the aggregation of the peptides in bulk, investigated by the Atomic Force Microscope and Zeta Potential. Images of secondary structures formed in solution by each peptide were produced, as well as providing information on the charges of the solution and the colloidal stability, showing the need for an added lipidated chain for peptide stability. Surface induced aggregation was then investigated through studying a variety of surfaces using the Quartz Crystal Microbalance with dissipation, giving both the wet mass adsorbed, as well as indications of the rigidity of the layer formed. The two most common surfaces used in the pharmaceutical industry; borosilicate glass and polystyrene, were amongst the surfaces investigated and were shown to cause the highest adsorption of peptide, ranking as the least effective surfaces at preventing aggregation. Another factor determining peptide adsorption to surfaces is roughness. Surfaces of different roughness were created through addition of gold nanoparticles, and using the QCM-D, adsorption was compared to that of flat gold surfaces. An increase of adsorption on flat surfaces compared to rougher surfaces was found, indicating a more intricate relationship than previously thought. E- beam lithography was then used to create different nanostructures on the gold surface. Ultimately, the thesis aimed at tackling a large problem within the pharmaceutical industry, by providing alternative pathways to challenge the problem of aggregation through adsorption to primary containers.

Name dc:type.qualificationname

Doctor of Philosophy (PhD)

Level dc:type.qualificationlevel

Doctoral

Grantor dc:publisher.institution

University of Cambridge

Year dc:date.issued

2019

Author dc:creator

• Baekelandt, Geraldine

Advisor dc:contributor.advisor

• Welland, Mark

• peptide
• adsorption
• aggregation
• surface adsorption

Licence

• https://apollo8-f-pro.lib.cam.ac.uk/bitstreams/3d0ed86c-a903-4391-8ec7-dd796b936aa9/download
• https://www.rioxx.net/licenses/all-rights-reserved/

Language dc:language

eng

DOI dc:identifier.doi

https://doi.org/10.17863/CAM.52684

OAI identifier oai:identifier

oai:www.repository.cam.ac.uk:1810/305607