A study on the impact of primary packaging interfaces on protein adsorption and stability

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dc.check.date2026-09-30
dc.contributor.advisorRyan, Katie
dc.contributor.advisorCrean, Abina
dc.contributor.authorDowney, John D.en
dc.contributor.funderSynthesis and Solid State Pharmaceutical Centreen
dc.contributor.funderScience Foundation Irelanden
dc.contributor.funderEngineering and Physical Sciences Research Councilen
dc.date.accessioned2025-05-29T10:38:51Z
dc.date.available2025-05-29T10:38:51Z
dc.date.issued2024en
dc.date.submitted2024
dc.description.abstractProtein-based therapies represent a transformative class of biotherapeutics, yet their stability remains a critical challenge. Therapeutic proteins are intrinsically unstable molecules owing to their structural complexity and amphiphilic properties and potential to adsorb to interfaces present during the product development lifecycle and shelf-life. Protein adsorption promotes unfolding and aggregation which can result in altered bioactivity of the therapeutic moiety or particle formation in solution. Consequently, there is an increased risk of deleterious effects such as lack of efficacy upon administration or an adverse immunogenic reaction. To overcome these challenges, rational formulation design and selection of compatible packaging materials can minimise protein adsorption. However, the excipients used in biological medicines have drawbacks such as poor chemical stability in aqueous solution and the potential to degrade packaging coatings. Moreover, owing to the stringent requirements for primary packaging materials, innovative packaging solutions have not received significant attention to date. The overall aim of this thesis is to explore the impact of packaging interfaces and formulation on the adsorption and stability of two model proteins, lysozyme and bovine serum albumin (BSA), and develop novel formulation and packaging mitigation strategies to minimise the adverse impacts arising from protein-packaging interactions. Chapter One introduces protein therapeutics, focusing on their higher order structure, the impact of various stresses on protein physicochemical stability and formulation requirements to maintain stability. It also considers primary packaging for liquid parenterals and the impact of the protein formulation on container/closure compatibility. Chapter Two reviews prior literature on protein adsorption-induced instability during fill pumping and storage. Topics include factors influencing protein adsorption behaviour, interfaces present during unit operations, pump and tubing types, primary packaging materials, excipient-packaging incompatibility, and formulation considerations. Chapters Three, Four and Five focus on investigating the gaps in the formulation and packaging approaches to reduce protein adsorption and instability identified in Chapter Two. Chapter Three principally explores the effect of buffer type and pH on lysozyme adsorption to borosilicate glass. Lysozyme adsorption to borosilicate was found to be mediated by electrostatic interactions owing to the ionisation of glass in aqueous solutions generating an anionic material interface. Buffer type did not have a significant impact on the quantity of adsorbed lysozyme, but it was found to influence the properties of the adsorbed protein layer. Chapter Four examines the effect of vial orientation (upright versus inverted storage) on BSA stability under different storage conditions over one week. Inverted storage in vials with polydimethylsiloxane-coated stoppers at 40°C under agitation resulted in greater protein unfolding and aggregation. Packaging and formulation mitigation strategies of altering the vial stopper to an ethylene tetrafluoroethylene coating and including leucine as an aggregation suppressor were shown to be unsuitable for maintaining BSA in its native conformation under these storage conditions. Chapter Five focuses on developing an innovative vial stopper coating to reduce protein instability where sustained contact with vial stoppers occurs. A copolymer, poly(MPC-co-BMA), comprised of 2-methacryloyloxyethyl phosphorylcholine and butyl methacrylate was used to deposit a thin film coating to bromobutyl rubber stoppers using an innovative aerosol-assisted cold plasma deposition technique. Plasma process parameters (flow rate, speed and voltage) were found to affect coating coverage as indicated by changes in stopper hydrophobicity. BSA compatibility with poly(MPC-co-BMA)-coated stoppers was found to be comparable to commercial polydimethylsiloxane and ethylene tetrafluoroethylene stopper coatings over a 3-month storage period. Chapter Six provides a general discussion of the research performed and presents the key findings, limitations, future work and conclusions of this thesis. In brief, this thesis investigates how packaging interfaces and formulations affect protein adsorption and stability, focusing on strategies to mitigate protein instability. This thesis found that for the lysozyme, adsorption can be controlled by the solution pH and that for BSA, interfacial stress plays a minor role while storage environments significantly impact stability. Additionally, aerosol-assisted, low-temperature plasma is a viable thin film coating deposition technique for pharmaceutical packaging but requires further research to determine the long-term stability of the coating in the presence of liquid protein formulations.en
dc.description.statusNot peer revieweden
dc.description.versionAccepted Versionen
dc.format.mimetypeapplication/pdfen
dc.identifier.citationDowney, J. D. 2024. A study on the impact of primary packaging interfaces on protein adsorption and stability. PhD Thesis, University College Cork.
dc.identifier.endpage196
dc.identifier.urihttps://hdl.handle.net/10468/17585
dc.language.isoenen
dc.publisherUniversity College Corken
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/EPSRC-SFI Centres for Doctoral Training (CDT) Partnership/18/EPSRC-CDT/3587/IE/EPSRC-SFI Centre for Doctoral Training in Transformative Pharmaceutical Technologies/en
dc.relation.projectinfo:eu-repo/grantAgreement/UKRI/EPSRC/EP/S023054/1/GB/'EPSRC and SFI Centre for Doctoral Training in Transformative Pharmaceutical Technologies/en
dc.relation.projectinfo:eu-repo/grantAgreement/SFI/SFI Research Centres/12/RC/2275/IE/Synthesis and Solid State Pharmaceutical Centre (SSPC)/en
dc.rights© 2024, John Downey.
dc.rights.urihttps://creativecommons.org/licenses/by/4.0/
dc.subjectAdsorptionen
dc.subjectBiomanufactureen
dc.subjectStabilityen
dc.subjectInterfacesen
dc.subjectParticlesen
dc.subjectMitigationen
dc.subjectPackagingen
dc.subjectFormulationen
dc.titleA study on the impact of primary packaging interfaces on protein adsorption and stability
dc.typeDoctoral thesisen
dc.type.qualificationlevelDoctoralen
dc.type.qualificationnamePhD - Doctor of Philosophyen
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