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Transport of poly-L-lysine into oppositely charged poly(acrylic acid) microgels and its effect on gel deswelling.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
2008 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, Vol. 323, no 1, 60-9 p.Article in journal (Refereed) Published
Abstract [en]

The interaction between poly-L-lysine (pLys) and oppositely charged poly(acrylic acid) (pAA) microgels (Ø approximately 80-120 microm) was studied by micromanipulator-assisted light microscopy and confocal laser scanning microscopy. The aim of this study was to investigate effects of peptide size, pH, and salt concentration on binding, transport, and distribution of pLys in pAA microgel particles and thereby also to outline the details of the gel deswelling in response to pLys binding and incorporation. Both peptide distribution and gel deswelling kinetics were found to be strongly influenced by the pLys molecular weight, originating partly from limited entry of large peptides into the gel particle core. Also pH was shown to influence both deswelling and pLys incorporation kinetics, with a decreased deswelling rate observed with increasing pH. These effects are determined by a complex interplay between the pH-dependence of both pLys and the gel network, also influencing volume transitions of the latter. Finally, salt concentration was shown to have a significant effect on both gel deswelling rate and pLys transport, with an increased electrolyte concentration resulting in decreased deswelling rate but also in an increased peptide transport rate within the microgel particles.

Place, publisher, year, edition, pages
2008. Vol. 323, no 1, 60-9 p.
Keyword [en]
confocal microscopy, deswelling, kinetics, microgel, peptide; poly(acrylic acid), poly-L-lysine
National Category
Pharmaceutical Sciences
Identifiers
URN: urn:nbn:se:uu:diva-86864DOI: 10.1016/j.jcis.2008.03.003ISI: 000256646600008PubMedID: 18402972OAI: oai:DiVA.org:uu-86864DiVA: diva2:127523
Available from: 2008-12-08 Created: 2008-12-08 Last updated: 2009-11-02Bibliographically approved
In thesis
1. Interaction Between Microgels and Oppositely Charged Peptides
Open this publication in new window or tab >>Interaction Between Microgels and Oppositely Charged Peptides
2009 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Lightly cross-linked polyelectrolyte microgels are materials with interesting properties for a range of applications. For instance, the volume of these particles can be drastically changed in response to pH, ionic strength, temperature, or the concentration of specific ions and metabolites. In addition, microgel particles can bind substantial amounts of oppositely charged substances, such as proteins and peptides, and release them upon changes in the external environment. Consequently, microgels have potential in catalysis, photonics, biomaterials, and not at least, as protective and stimuli-sensitive carriers for protein and peptide drugs.

In this thesis, the interaction between anionic microgels and cationic peptides was investigated by monitoring microgel deswelling and reswelling in response to peptide binding and release using micromanipulator-assisted light microscopy. In addition, peptide distribution in microgels was analyzed with confocal laser scanning microscopy and peptide uptake determined with solution depletion measurements. The aim of the thesis was to clarify how parameters such as peptide size, charge density, pH, ionic strength and hydrophobicity influences the peptide binding to, distribution in and release from, polyelectrolyte microgels.

Results obtained in this thesis show that electrostatic attraction is a prerequisite for interaction to occur although non-electrostatic contributions are responsible the finer details of the interactions. The size and charge density of the interacting peptides play a major role, as large and highly charged peptides are restricted to enter and interact with the microgel core, thus displaying a surface-confined distribution. The peptide-microgel interaction strength is highly reflected in the probability of peptides to be detached from the gel network. For instance, reducing the electrostatic interactions by adding salt induces significant peptide release of sufficiently small and moderately charged peptides, whereas longer and more highly charged peptides is retained in the microgel network due to the strong interaction, insufficient salt screening, and gel network pore size restriction. Decreasing the charge density of microgel network and/or peptides increases the probability for peptide detachment tremendously.

To summarize, interactions occurring in oppositely charged microgel-peptide systems can be tuned by varying parameters such as charge density and peptide size and through this, the peptide uptake, distribution and release can be controlled to alter the performance of microgels in peptide drug delivery.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2009. 68 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 113
Keyword
antimicrobial peptides, binding, cationic peptides, confocal microscopy, deswelling, distribution, electrostatic, homopolypeptides, microgels, peptides, release, swelling
National Category
Pharmaceutical Sciences
Research subject
Pharmaceutical Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-109203 (URN)978-91-554-7635-9 (ISBN)
Public defence
2009-11-27, B21, BMC, Husargatan 3, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2009-11-06 Created: 2009-10-12 Last updated: 2009-11-06

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