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.

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.

This thesis describes the design, synthesis and characterization of organo-phosphatemonomolecular layers, so called self-assembled monolayers, using the strategy of linking organosulfur substances to a gold surface. Moreover there is also a paper included, which describes the development of synthetic pathways to various phospholipids, for which I have developed an interest in later projects.

For the first study of the properties of phosphates, and also for concomitant application of developed systems, analogues of the amino acids serine, threonine and tyrosine, phosphorylated and non-phosphorylated, were synthesized. 16-Mercaptohexadecanamide based analogues were characterized as monolayers and large polar and charge effects were observed, introduced by the phosphate. Problems were, however, encountered as a post modification of phosphates was applied and a disordering of the monolayers observed. Moreover there were no expected effects observable upon interaction with Ca²⁺ and Mg²⁺.

Based on the conclusions from the first study 3-mercaptopropionamide based analogues were used instead. Characterization of the analogues including counter ion exchange (H⁺,Na⁺, Ca²⁺ and Mg²⁺) revealed large electronic and possible structural differences depending on the counter ion.

Again the charge and polar effects induced by the phosphate were investigated, and the study was also extended to interaction of the phosphate with Ca²⁺ and Mg²⁺. Strong effects were observed, which were also dependent on the ion concentration within a significant range. The polarity and charge properties of the phosphate layer were thus found to be variable.

In the fourth study an additional Ca²⁺ and Mg²⁺ sensitive system was applied in combination with the phosphate surface. Phosphate surface/phospholipid vesicle interactions were studied under different conditions of Mg²⁺ (Ca²⁺) treatment. For comparison, the corresponding hydroxyl and sulphate surfaces were included and also the most well characterized surface concerning phospholipid vesicle interaction, SiO₂. Most importantly, supported phospholipid bilayer (SPB) formation was found to be inducible on both the phosphate and sulphate surfaces, however at defined conditions of Mg²⁺ (Ca²⁺) treatment and concentration. The conclusion is that the processes of phospholipid vesicle adsorption and SPB formation are largely dependent on vesicle/surface interaction and vesicle stability.

The last paper included in this thesis is a synthetic method development aimed at easy preparations of various phospholipid derivatives. In the future these methods could be used for synthesis of functionalized lipids and aid in the development of models mimicking biological systems such as artificial cell membranes.