liu.seSearch for publications in DiVA
Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Bioactive monolayers and thin films for biomedical applications
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
2006 (English)Licentiate thesis, comprehensive summary (Other academic)
Abstract [en]

This thesis includes two projects. The first one is a study of organic molecular self assembled monolayers designed to promote selective protein adsorption processes. The second one describes a high quality, freestanding films based on biodegradable chitosan obtained through a controlled preparation process and investigated as a promising system for many applications including biomaterials.

Within the first part of this work it was explored selective adsorbates for molecular recognition based on positively charged peptide and it has studied how the biomolecules are expressed when adsorbed to the surface. The design and the preparation of a peptide modified surface were done to investigate G-protein interactions. Pure and mixed monolayers of a synthetic peptide, GPR-i3n, derived from the 3rd intracellular loop of the α2 Adrenergic Receptor and a smaller inactive oligopeptide, N-formyi-(Gly) 3- (Cys) called 3GC, were prepared. In this study, 3GC is chosen as a co-adsorbent, with the aim to induce molecular conformational changes of GPR-i3n during the monolayer formation to improve the G-protein adsorption to the functionalized surface.

The formation and the chemical composition of the peptide monolayers on the surface were investigated as well as the monolayers thickness and the mass related surface coverage. The interaction between the mixed monolayers and G-proteins was investigated by means of real time Surface Plasmon Resonance (SPR). There is a higher protein binding capacity to the monolayer when the GPR-i3n peptide is intermixed with the 3GC coadsorbent, despite the fact that the 3GC itself has a very low G-protein binding capability. This supports our theory that a molecular reorientation of the GPR-i3n peptide occurs on the surface when 3GC is intermixed with GPR-i3n.

The formation of SAMs is described in chapter 4 and a full characterization of the mixed monolayers is reported as well as a G-protein interaction study.

In terms of biomaterials, a fundamental understanding of the structure and the composition of the surfaces is necessary for a successful design or when interacting with human body.

The objective of the second study was to thoroughly investigate the properties of free standing chitosan films, prepared by dry phase inversion from chitosan solutions in acetic acid. The films of chitosan were transparent with very good flexibility, while thicker films were fragile, showing an increase of internal tension with thickness. Structural analysis by X-ray diffraction (XRD) proved that the films as initially prepared are almost amorphous. Subsequent annealing converted the amorphous films into a mixture of amorphous and crystalline phases. The investigations by thermogravimetry (TG), the derivative (DTG) and the differential thermal curves (DTA) showed that the thermal degradation of chitosan films as initially prepared proceeds in two stages. The first decomposition stage corresponds to a complex series of processes including dehydration of saccharide rings, depolymerization and decomposition of the acetylated and deacetylated units of the polymers.

The methods used for surface analysis can provide information about the biomaterials, information that can be used to ensure the surface reproducibility and the fundamental aspects toward the interaction of biological systems with living systems.

Place, publisher, year, edition, pages
Linköping: Linköping University , 2006. , 42 p.
Series
Linköping Studies in Science and Technology. Thesis, ISSN 0280-7971 ; 1268
National Category
Natural Sciences
Identifiers
URN: urn:nbn:se:liu:diva-36128Local ID: 30009ISBN: 91-85643-92-0 (print)OAI: oai:DiVA.org:liu-36128DiVA: diva2:256976
Note

Licentiate thesis no 1268

Available from: 2009-10-10 Created: 2009-10-10 Last updated: 2013-12-17
List of papers
1. Mixed monolayers to promote G-protein adsorption: α2A- Adrenergic receptor-derived peptides coadsorbed with formyl-terminated oligopeptides
Open this publication in new window or tab >>Mixed monolayers to promote G-protein adsorption: α2A- Adrenergic receptor-derived peptides coadsorbed with formyl-terminated oligopeptides
2007 (English)In: Langmuir, ISSN 0743-7463, E-ISSN 1520-5827, Vol. 23, no 16, 8474-8479 p.Article in journal (Refereed) Published
Abstract [en]

Pure and mixed monolayers of a synthetic peptide, GPR-i3n, derived from the third intracellular loop of the α2 adrenergic receptor and a shorter inactive oligopeptide, N-formyl-(Gly)3-(Cys) (called 3GC), were prepared on gold surfaces. The mixing ratio of the GPR-i3n and 3GC was used to control G-protein binding capability. The GPR-i3n peptide is specially designed for bovine G-protein selectivity and has been proven to have high affinity to G-proteins [Vahlberg, C.; Petoral, R. M., Jr.; Lindell, C.; Broo, K.; Uvdal, K. Langmuir 2006, 22 (17), 7260−7264]. Pure 3GC monolayers show very low protein adsorption capability. In this study, 3GC is chosen as a coadsorbent, with the aim to induce molecular conformational changes during monolayer formation to enhance G-protein adsorption. A full characterization of the mixed monolayers was done. The monolayer thickness and the mass-related surface coverage for both GPR-i3n and 3GC were investigated using radio labeling. The GPR-i3n was labeled by 125I-targeting tyrosine, and the activity was measured by using radioimmunoassay (RIA). The formation and chemical composition of GPR-i3n and 3GC monolayers were investigated using X-ray photoelectron spectroscopy, and it is shown that both GPR-i3n and 3GC bind chemically to the gold surface. The interaction between the mixed monolayers and G-proteins was investigated by means of real-time surface plasmon resonance. There is a higher protein binding capacity to the monolayer when the GPR-i3n peptide is intermixed with the 3GC coadsorbent, despite the fact that the 3GC itself has a very low G-protein binding capability. This supports a molecular reorientation at the surface, while 3GC is intermixed with GPR-i3n.

National Category
Engineering and Technology
Identifiers
urn:nbn:se:liu:diva-47944 (URN)10.1021/la063447f (DOI)000248229900028 ()
Available from: 2009-10-11 Created: 2009-10-11 Last updated: 2017-12-13Bibliographically approved
2. Physico-chemical properties of Chitosan films
Open this publication in new window or tab >>Physico-chemical properties of Chitosan films
Show others...
2004 (English)In: Central European Journal of Chemistry, ISSN 1895-1066, E-ISSN 1644-3624, Vol. 2, no 4, 638-647 p.Article in journal (Refereed) Published
Abstract [en]

Chitosan films obtained by dry phase inversion were prepared from an aqueous solution of chitosan in acetic acid. The films, of thickness less than 20 μm, were transparent, very flexible and had smooth surfaces. Increasing the film thickness induced an increase of the internal tensions and the consequent formation of a rough surface. Structural investigations by X-ray diffraction and Fourier transform IR analysis, showed that the chitosan films, as prepared, are amorphous. Further annealing to evaporate acetic acid and water traces, changed the amorphous phase into a more ordered phase, characterized by diffraction peaks at 2θ values of 9, 17, 20 and 23 degrees. Thermal investigations by TG, DTG, and DTA revealed that the decomposition of the chitosan films as prepared proceeds in two stages, starting from 180°C and 540°C.

National Category
Natural Sciences
Identifiers
urn:nbn:se:liu:diva-102629 (URN)10.2478/BF02482727 (DOI)000224491700008 ()
Available from: 2013-12-17 Created: 2013-12-17 Last updated: 2017-12-06

Open Access in DiVA

No full text

Authority records BETA

Savitchi, Luminita

Search in DiVA

By author/editor
Savitchi, Luminita
By organisation
Department of Physics, Chemistry and BiologyThe Institute of Technology
Natural Sciences

Search outside of DiVA

GoogleGoogle Scholar

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 41 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • harvard1
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • oxford
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf