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Electrostatic Swelling Transitions in Surface-Bound Microgels
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
KTH Royal Inst Technol, Sch Chem Sci & Engn, Dept Surface & Corros Sci, SE-10044 Stockholm, Sweden.;IMDEA Nanosci, Inst Adv Studies, Madrid 28049, Spain..
Uppsala University, Disciplinary Domain of Medicine and Pharmacy, Faculty of Pharmacy, Department of Pharmacy.
Univ Manchester, Sch Mat, MSS Tower, Manchester M13 9PL, Lancs, England..
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2016 (English)In: ACS Applied Materials and Interfaces, ISSN 1944-8244, E-ISSN 1944-8252, Vol. 8, no 40, p. 27129-27139Article in journal (Refereed) Published
Abstract [en]

Herein, electrostatic swelling transitions of poly (ethyl acrylate-co-methacrylic acid) microgels covalently bound to silica surfaces are investigated. Confined at a solid surface, microgel swelling is anisotropically hindered and the structure is flattened to an extent dictated by pH and microgel composition. Microgel deformation under applied load is also shown to depend on microgel charge density, with the highest deformation observed at intermediate charge densities. Two modes of microgel deformation under load were observed, one elastic and one viscoelastic, related to polymer strand deformation and displacement of trapped water, respectively. Results on polymer strand dynamics reveal that the microgels are highly dynamic, as the number of strand-tip interaction points increases 4-fold during a 10 s contact time. Furthermore, finite element modeling captures these effects qualitatively and shows that stress propagation in the microgel network decays locally at the rim of contact with a solid interface or close to the tip probe. Taken together, the results demonstrate a delicate interplay between the surface and microgel which determines the structure and nanomechanical properties of the latter and needs to be controlled in applications of systems such as pH-responsive surface coatings in biomaterials.

Place, publisher, year, edition, pages
2016. Vol. 8, no 40, p. 27129-27139
Keywords [en]
atomic force microscopy, finite element method, microgel, pH-responsive, quartz crystal microbalance, surface-bound
National Category
Biomaterials Science
Identifiers
URN: urn:nbn:se:uu:diva-307540DOI: 10.1021/acsami.6b09751ISI: 000385469000081PubMedID: 27644921OAI: oai:DiVA.org:uu-307540DiVA, id: diva2:1047312
Funder
Swedish Research Council, 2012-1842 2013-4384Knut and Alice Wallenberg Foundation, KAW 2012.0078Available from: 2016-11-17 Created: 2016-11-17 Last updated: 2018-10-12Bibliographically approved
In thesis
1. Microgels as Carriers for Antimicrobial Peptides: Surface-bound microgels, and factors affecting peptide interactions
Open this publication in new window or tab >>Microgels as Carriers for Antimicrobial Peptides: Surface-bound microgels, and factors affecting peptide interactions
2018 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

With a growing number of multi-resistant bacteria against conventional antibiotics, there is an urgent need to identify new antimicrobial therapeutics. One example that has gained considerable interest is antimicrobial peptides (AMPs). For AMPs to reach their full potential as therapeutics, as well as for other peptide and protein drugs, the right drug delivery system may overcome reported shortcomings, such as fast clearance in the bloodstream and proteolytic degradation. Microgels are weakly cross-linked polymer colloids, which can be made responsive to various stimuli. In the context of drug delivery, microgels are of particular interest as carriers for biomacromolecular drugs, such as peptides and proteins, as their water-rich environment offers both protection against enzymatic degradation and triggered release possibilities. Combining these, the aim of this thesis was to investigate electrostatically triggered surface-bound microgels as a delivery system for AMPs, as well as evaluate such systems as an antimicrobial and anti-inflammatory coating for biomaterials.

Results presented in this thesis demonstrate effects of microgel charge density, pH, and ionic strength on microgel volume transitions at solid interfaces, surface-induced microgel deformation and nanomechanical properties. In addition, effects of both microgel properties (charge density) and peptide properties (molecular weight, charge density, and posttranslational modifications) on peptide loading and release from surface-bound microgels were investigated. The presented thesis also reports in vitro studies of AMP-loaded microgels in dispersion and surface-bound, as either mono- or multilayers. Notably, the interplay between surface- and release-related effects for the antimicrobial properties of AMP-loaded microgels are investigated. In addition, anti-inflammatory properties of AMP-loaded microgels are also reported.

Taken together, microgels prove an interesting and versatile drug delivery system for AMPs. Results obtained in this thesis have demonstrated that several key factors need to be taken into consideration in the development of surface-bound microgels as a carrier for AMPs, and that small changes in microgel and peptide properties can alter peptide loading and release profiles.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2018. p. 66
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Pharmacy, ISSN 1651-6192 ; 259
Keywords
Antimicrobial peptides, Biomaterial coating, Drug delivery, Host defence peptides, Microgels, pH-responsive, Surface-bound
National Category
Pharmaceutical Sciences Biomaterials Science Physical Chemistry
Research subject
Pharmaceutical Physical Chemistry
Identifiers
urn:nbn:se:uu:diva-360241 (URN)978-91-513-0473-1 (ISBN)
Public defence
2018-11-30, A1:111a, BMC, Husargatan 3, Uppsala, 09:15 (English)
Opponent
Supervisors
Available from: 2018-11-09 Created: 2018-10-12 Last updated: 2018-11-19

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