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Tuning the density profile of surface-grafted hyaluronan and the effect of counter-ions
Uppsala University, Science for Life Laboratory, SciLifeLab. Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry.
Institut Laue-Langevin.
Uppsala University, Disciplinary Domain of Science and Technology, Chemistry, Department of Chemistry - Ångström, Polymer Chemistry. Uppsala University, Science for Life Laboratory, SciLifeLab.
Uppsala University, Disciplinary Domain of Science and Technology, Physics, Department of Physics and Astronomy, Materials Physics.
2013 (English)In: European Physical Journal E, ISSN 1292-8941, Vol. 36, no 7, 70- p.Article in journal (Refereed) Published
Abstract [en]

The present paper investigates the structure and composition of grafted sodium hyaluronanat a solid-liquid interface using neutron reflection. The solvated polymer at the surface could be described with a density profile that decays exponentially towards the bulk solution. The density profileof the polymer varied depending on the deposition protocol. A single-stage deposition resulted in denser polymer layers, while layers created with a two-stage deposition process were more diffuse and had an overall lower density. Despite the diffuse density profile, two-stage deposition leads to a highersurface excess. Addition of calcium ions causes a strong collapse of the sodium hyaluronan chains, increasing the polymer density near the surface. This effect is more pronounced on the sample prepared by two-stage deposition due to the initial less dense profile. This study provides an understanding at a molecular level of how surface functionalization alters the structure and howsurface layers respond to changes in calcium ions in the solvent.

Place, publisher, year, edition, pages
2013. Vol. 36, no 7, 70- p.
National Category
Polymer Technologies Polymer Chemistry
Identifiers
URN: urn:nbn:se:uu:diva-197814DOI: 10.1140/epje/i2013-13070-7ISI: 000322872700002OAI: oai:DiVA.org:uu-197814DiVA: diva2:614347
Available from: 2013-04-04 Created: 2013-04-04 Last updated: 2014-02-17Bibliographically approved
In thesis
1. Relating the Bulk and Interface Structure of Hyaluronan to Physical Properties of Future Biomaterials
Open this publication in new window or tab >>Relating the Bulk and Interface Structure of Hyaluronan to Physical Properties of Future Biomaterials
2013 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

This dissertation describes a structural investigation of hyaluronan (HA) with neutron scattering techniques. HA is a natural biopolymer and one of the major components of the extracellular matrix, synovial fluid, and vitreous humor.  It is used in several biomedical applications like tissue engineering, drug delivery, and treatment of osteoarthritis. Although HA is extensively studied, very little is known about its three-dimensional conformation and how it interacts with ions and other molecules. The study aims to understand the bulk structure of a cross-linked HA hydrogel, as well as the conformational arrangement of HA at solid-liquid interfaces. In addition, the structural changes of HA are investigated by simulation of physiological environments, such as changes in ions, interactions with nanoparticles, and proteins etc. Small-angle neutron scattering and neutron reflectivity are the two main techniques applied to investigate the nanostructure of hyaluronan in its original, hydrated state.

The present study on hydrogels shows that they possess inhomogeneous structures best described with two correlation lengths, one of the order of a few nanometers and the other in the order of few hundred nanometers. These gels are made up of dense polymer-rich clusters linked to each other. The polymer concentration and mixing governs the connectivity between these clusters, which in turn determines the viscoelastic properties of the gels. Surface-tethered HA at a solid-liquid interface is best described with a smooth varying density profile. The shape of this profile depends on the immobilization chemistry, the deposition protocol, and the ionic interactions. HA could be suitably modified to enhance adherence to metal surfaces, as well as incorporation of proteins like growth factors with tunable release properties. This could be exploited for surface coating of implants with bioactive molecules. The knowledge gained from this work would significantly help to develop future biomaterials and surface coatings of implants and biomedical devices.

Place, publisher, year, edition, pages
Uppsala: Acta Universitatis Upsaliensis, 2013. 66 p.
Series
Digital Comprehensive Summaries of Uppsala Dissertations from the Faculty of Science and Technology, ISSN 1651-6214 ; 1043
Keyword
hyaluronan, structure, bulk, interface, small-angle neutron scattering, neutron reflection, hydrogel, grafting, nanoparticles, protein interactions
National Category
Polymer Chemistry Materials Chemistry
Identifiers
urn:nbn:se:uu:diva-198357 (URN)978-91-554-8669-3 (ISBN)
Public defence
2013-06-05, Häggsalen, Ångströmlaboratoriet, Lägerhyddsvägen 1, Uppsala, 09:00 (English)
Opponent
Supervisors
Available from: 2013-05-15 Created: 2013-04-12 Last updated: 2013-08-30Bibliographically approved

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Hilborn, JönsRennie, Adrian R.

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