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Multilayers of Charged Polypeptides As Studied by in Situ Ellipsometry and Quartz Crystal Microbalance with Dissipation
KTH, Superseded Departments, Chemistry.
YKI, Institute for Surface Chemistry.
2004 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 20, no 5, 1739-1745 p.Article in journal (Refereed) Published
Abstract [en]

The buildup of poly(L-glutamic acid) (PGA) and poly(L-lysine) (PLL) multilayers on silica and titanium surfaces, with and without an initial layer of polyethyleneimine (PEI), was investigated and characterized by means of in situ ellipsometry and quartz crystal microbalance with dissipation. A two-regime buildup was found in all systems, where the length of the first slow-growing regime is dependent on the structure of the initial layers. In the second fast-growing regime, the film thickness grows linearly while the mass increases more than linearly (close to exponentially) with the number of deposited layers. The film refractive indices as well as the water contents indicate that the film density changes as the multilayer film builds up. The change in film density was proposed to be due to polypeptides diffusing into the multilayer film as they attach. Furthermore, the use of PEI as the initial layer was found to induce a difference in the thickness increments for PGA and PLL.

Place, publisher, year, edition, pages
2004. Vol. 20, no 5, 1739-1745 p.
Keyword [en]
Biocompatibility, Biopolymers, Composition, Density (specific gravity), Ellipsometry, Multilayers, Polyelectrolytes, Refractive index, Silica, Surfaces, Titanium, Water, Film thickness, Poly l glutamic acid, Poly l lysine, Quartz crystal microbalance, Thickness increment
National Category
Physical Chemistry
URN: urn:nbn:se:kth:diva-8920DOI: 10.1021/la035475tISI: 000189241500030ScopusID: 2-s2.0-1542315206OAI: diva2:14406
QC 20101019Available from: 2005-12-08 Created: 2005-12-08 Last updated: 2011-10-27Bibliographically approved
In thesis
1. Multilayer Structures for Biomaterial Applications: Biomacromolecule-based Coatings
Open this publication in new window or tab >>Multilayer Structures for Biomaterial Applications: Biomacromolecule-based Coatings
2005 (English)Doctoral thesis, comprehensive summary (Other scientific)
Abstract [en]

The cellular response to a biomaterial, such as a dental implant, is mainly governed by the surface properties, and can thus be altered by the introduction of a surface coating. In this thesis the buildup of a biomacromolecule-based coating formed by layerby-layer (LbL) deposition of the charged polypeptides poly(L-lysine) (PLL) and poly(L-glutamic acid) (PGA) has been studied. In an attempt to make these coatings bioactive and useful for bone-anchored implants, an amelogenin protein mixture (EMD), has been immobilized in these thin polyelectrolyte multilayer (PEM) films. Multilayers were also built by LbL deposition of the natural biomacromolecules collagen (Col) and hyaluronic acid (HA). Multilayer films of these two extra-cellular biomacromolecules should be of interest for use as a scaffold for tissue engineering.

The buildup of the multilayer films has been followed in situ, using ellipsometry, quartz crystal microbalance with dissipation (QCM-D), and dual polarization interferometry (DPI). The studied PLL/PGA multilayers were found to be highly hydrated, and to exhibit a two-regime buildup behavior, with an initial “slow-growing” regime, and a second “fast-growing” regime with a linear growth in film thickness and more than linear growth in mass. A net diffusion of polypeptides into the film during the buildup led to an increase in density of the films for each layer adsorbed. A change in density was also observed in the Col/HA film, where HA penetrated and diffused into the porous fibrous Col network.

The formed PLL/PGA films were further found to be rather stable during drying, and post-buildup changes in temperature and pH, not losing any mass as long as the temperature was not raised too rapidly. The film thickness responded to changes in the ambient media and collapsed reversibly when dried. A swelling/de-swelling behavior of the film was also observed for changes in the temperature and pH.

The EMD protein adsorbed to silica surfaces as nanospheres, and could by itself form multilayers. The adsorption of EMD onto PLL/PGA multilayer films increased at lower pH (5.0), and EMD could be immobilized in several layers by alternate deposition of EMD and PGA.

Place, publisher, year, edition, pages
Stockholm: KTH, 2005. xvii, 67 p.
Trita-YTK, ISSN 1650-0490 ; 0505
multilayer, layer-by-layer deposition, physical chemistry, surface chemistry, adsorption, ellipsometry, QCM-D, DPI, protein adsorption, polypeptides, biomaterials, biosurfaces, amelogenin, solid/liquid interface
National Category
Physical Chemistry
urn:nbn:se:kth:diva-551 (URN)91-7178-216-8 (ISBN)
Public defence
2005-12-16, F3, KTH, Lindstedtsvägen 26, Stockholm, 13:00
QC 20101019Available from: 2005-12-08 Created: 2005-12-08 Last updated: 2010-10-19Bibliographically approved

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