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Synthesis and Monolayer Characterization of Phosphorylated Amino Acid Analogs
Linköping University, Department of Physics, Chemistry and Biology. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Organic Chemistry. Linköping University, The Institute of Technology.
Linköping University, Department of Physics, Chemistry and Biology, Sensor Science and Molecular Physics. Linköping University, The Institute of Technology.
2002 (English)In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 254, no 2, 322-330 p.Article in journal (Refereed) Published
Abstract [en]

The synthesis of a series of thiols containing phosphorylated and non-phosphorylated serine, threonine, and tyrosine amino acid residues is described. The synthesized molecules, based on 3-mercaptopropionic acid, were assembled onto gold and subsequently characterized using infrared reflection-absorption spectroscopy, ellipsometry, X-ray photoelectron spectroscopy, and contact angle goniometry. The ellipsometric analysis indicates that they form densely packed and well-oriented monolayers on gold, with thicknesses that are in good agreement with estimated values from space-filling models. The bulky and space-demanding phosphorylated threonine analog was, however, found to be an exception. The increase in layer thickness when adding a phosphate group to the threonine is only 35% of that observed for the two other analogs. A detailed infrared examination of the influence of cation coordination to the phosphorylated serine analog using calcium and magnesium reveals structural similarities to those of the inorganic phosphate compound calcium hydroxy apatite. We furthermore discuss the application of these monolayers as soft templates for biomineralization.

Place, publisher, year, edition, pages
Maryland Heights, MO, United States: Academic Press, 2002. Vol. 254, no 2, 322-330 p.
Keyword [en]
SAM; phosphorylated amino acid; phosphate layer; alkanethiols; gold; counterion influence
National Category
Natural Sciences
URN: urn:nbn:se:liu:diva-14336DOI: 10.1006/jcis.2002.8576ISI: 000178935400016OAI: diva2:23265
Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2014-08-19Bibliographically approved
In thesis
1. Biomimetic surfaces: Preparation, characterization and application
Open this publication in new window or tab >>Biomimetic surfaces: Preparation, characterization and application
2007 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [sv]

I denna avhandling beskrivs tillverkning, karaktärisering och tillämpning av ett antal biomimetiska ytor. Biomimetik är att härma naturen och grundtanken är att titta på hur naturen löst liknande problemställningar. Två olika typer av modellsystem med inspiration från naturen har tagits fram för framtida tillämpningar inom bioanalys, biosensorer samt antifrysmaterial. Det ena typen av modellsystem innefattar fosforylerade ytor och det andra består av ytor som härmar antifrys(glyko)proteiner. Ytorna tillverkades av monolager av självorganiserande svavelorganiska molekyler och karaktäriserades före tillämpning med hjälp av ellipsometri, IR-spektroskopi, kontaktvinkelmätning och röntgenfotoelektronspektroskopi.

Modellsystemen för att studera vattenfrysning på ytor inspirerades av antifrys(glyko)proteiner som bl.a. kan hittas i polarfiskar. Två modellsystem utvecklades och studerades med avseende på frysning av kondenserat vatten. Det ena designades att härma den aktiva domänen hos ett antifrysglykoproteiner (AFGP) och det andra härmade typ I antifrysproteiner (AFP I). Frysstudierna visade på signifi-kanta skillnader för AFGP-modellen jämfört med ett (OH/CH3) referenssystem med jämförbar vätbarhet, men inte för AFP Imodellen. Vattnet frös vid högre temperatur för AFGPmodellen.

Modellsystemen med fosforylerade ytor inspirerades av fosforylering och biomineralisering. Två system utvecklades, ett med långa och ett med korta alkylkedjor på aminosyraanalogerna, både med och utan fosfatgrupp. En ny metod användes med skyddsgrupper på fosfaterna hos de långa analogerna innan bildandet av monolager. Skyddsgrupperna togs bort efter bildandet av monolager. Dessa monolager undersöktes också med elektrokemiska metoder och signifikant högre kapacitans observerades för de fosforylerade monolageren jämfört med de icke fosforylerade.

Abstract [en]

This thesis describes the preparation, characterization and application of a few biomimetic surfaces. Biomimetics is a modern development of the ancient Greek concept of mimesis, i.e. man-made imitation of nature. The emphasis has been on the preparation and characterization of two types of model systems with properties inspired by nature with future applications in bioanalysis, biosensors and antifreeze materials. One type of model system involves phosphorylated surfaces; the other consists of surfaces mimicking antifreeze (glyco)proteins. The surfaces were made by chemisorbing organosulfur substances to a gold surface into monomolecular layers, so called self-assembled monolayers (SAMs). The physicochemical properties of the SAMs were thoroughly characterized with null ellipsometry, contact angle goniometry, x-ray photoelectron spectroscopy and infrared spectroscopy prior to application.

The work on antifreeze surfaces was inspired by the structural properties of antifreeze (glyco)proteins, which can be found in polar fish. Two model systems were developed and studied with respect to ice nucleation of condensed water layers. One was designed to mimic the active domain of antifreeze glycoproteins (AFGP) and the other mimicked type I antifreeze proteins (AFP I). Subsequent ice nucleation studies showed a significant difference between the AFGP model and a (OH/CH3) reference system displaying identical wetting properties, whereas the AFP I model was indistinguishable from the reference system.

The model systems with phosphorylated surfaces were inspired from phosphorylations and biomineralization. Two systems were developed, short- and long-chained amino acid analogues, with and without a phosphate group. A novel approach with protected groups before attachment to gold were developed for the long-chained analogues. The protective groups could be removed successfully after assembly. The long-chained SAMs were evaluated with electrochemical methods and significantly higher capacitance values were observed for the phosphorylated SAMs compared to the non-phosphorylated.

Place, publisher, year, edition, pages
Institutionen för fysik, kemi och biologi, 2007. 84 p.
Linköping Studies in Science and Technology. Dissertations, ISSN 0345-7524 ; 1069
Self-assembled monolayers, biomimetic surfaces, phosphates, antifreeze, surface spectroscopy
National Category
Atom and Molecular Physics and Optics
urn:nbn:se:liu:diva-8492 (URN)978-91-85715-99-2 (ISBN)
Public defence
2007-03-30, Planck, Fysikhuset, Campus Valla, Linköping, 10:15 (English)
Available from: 2007-03-16 Created: 2007-03-16 Last updated: 2009-04-23

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Ekeroth, JohanBorgh, AnnikaKonradsson, PeterLiedberg, Bo
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