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Influence of pendant pyridyl regioisomers on the pH-responsive behaviour of polymer-homopeptide copolymers and micelles

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dc.contributor.authorDharmayanti, C.
dc.contributor.authorClulow, A.J.
dc.contributor.authorHussain, M.S.
dc.contributor.authorGillam, T.A.
dc.contributor.authorKlingler Hoffmann, M.
dc.contributor.authorAlbrecht, H.
dc.contributor.authorBlencowe, A.
dc.date.issued2025
dc.descriptionData source: Supplementary data, https://doi.org/10.1016/j.eurpolymj.2025.113931
dc.description.abstractPolymeric micelles that can respond to changes in pH have emerged as appealing systems to achieve localised drug release. These micelles can be prepared from homopeptide block copolymers, which are attractive alternatives to traditional synthetic polymers due to their unique ability to form secondary structures. However, naturally occurring amino acids have a limited variety of side chain functional groups, requiring additional modifications to tune pH-responsivity. In addition, further work is required to better understand how these structural changes to the peptide side chains can influence their pH-responsive behaviour and self-assembly. Herein, we investigate the pH responsive behaviour of a series of poly[(ethylene glycol)-b-(pyridinylmethyl glutamate)] (PEG-b-P#PG) copolymers modified with different pyridine regioisomers (para (# = 4), meta (# = 3), or ortho (# = 2) relative to the polymer chain). Potentiometric and nuclear magnetic resonance (NMR) spectroscopic titrations, coupled with zeta (zeta)-potential measurements, provided information on the ionisation behaviour of the copolymers and their acid dissociation constant (pK(a)) values. At neutral pH, the copolymers assembled into micelles with unique structures and exhibited characteristic pK(a) values resulting from the different pyridine regioisomers, which influenced the pH-responsive behaviour of the micelles. Changes in the morphology and secondary structure of the micelles as a function of pH were interrogated using dynamic light scattering (DLS), synchrotron small-angle X-ray scattering (SAXS) and circular dichroism (CD) spectroscopy. Disassembly of the PEG-b-P#PG micelles was observed when the solution pH was below the pK(a), indicating that a high degree of ionisation (> 85 %) is necessary to disrupt the secondary structures of the peptide blocks. These results provide important insights into the design of pH-responsive polymer-homopeptide block copolymers and the influence of side chain regioisomers on their ionisation and assembly behaviour.
dc.identifier.citationEuropean Polymer Journal, 2025; 234(113931):1-11
dc.identifier.doi10.1016/j.eurpolymj.2025.113931
dc.identifier.issn0014-3057
dc.identifier.issn1873-1945
dc.identifier.orcidAlbrecht, H. [0000-0002-3951-1866]
dc.identifier.orcidBlencowe, A. [0000-0002-7630-4874]
dc.identifier.urihttps://hdl.handle.net/11541.2/43574
dc.language.isoen
dc.publisherElsevier
dc.relation.fundingAustralian Government Research Training Program (RTP) Scholarship
dc.relation.fundingPostgraduate Research Award (PGRA)
dc.relation.fundingGould Experimental Science Grant Commendation M18917
dc.relation.fundingRoyal Australian Chemical Institute (RACI) Polymer Division
dc.relation.fundingAmerican Chemical Society CAS Future Leaders Program
dc.relation.fundingSoroptimist International of Adelaide
dc.relation.fundingAustralia Government NIPG-2022-001
dc.rightsCopyright 2025 Elsevier Access Condition Notes: Accepted manuscript available after 1 July 2027
dc.source.urihttps://doi.org/10.1016/j.eurpolymj.2025.113931
dc.subjectchemical shift
dc.subjectionization potential
dc.subjectmagic angle spinning
dc.subjectpeptides
dc.titleInfluence of pendant pyridyl regioisomers on the pH-responsive behaviour of polymer-homopeptide copolymers and micelles
dc.typeJournal article
pubs.publication-statusPublished
ror.fileinfo12304064520001831 13304064510001831 Open Access Postprint
ror.mmsid9917038740601831

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