| Membrane proteins are both structurally and functionally diverse. Present in biological membranes, their functions, mainly transport, signaling and surface recognition, depend on cell type and subcellular location. However, many questions on their interactions with cell membrane are still unanswered. For the thorough investigation of protein-lipid interactions, it is desirable to design simplified models of cell membranes. This work aims to find new approaches towards the development of membrane model systems to immobilize proteins. For the different models, zirconium phosphonate surfaces were used as a support for lipid bilayers. Two models, that provide stable, functional and reproducible membranes, have been developed to enable the immobilization of membrane proteins. In the first model, metal phosphonate chemistry was employed to increase the stability of lipid bilayers by means of covalent interactions. Phosphatidic acid lipid was used in a mixture of phospholipids to form covalent bonds with the latter surface. Additionally, the kinetic analyses of proteinbiosensor interaction were performed in order to verify the viability of these models as natural membrane. Membrane proteins were able to insert and maintained their structure in the membrane as shown by binding experiments, performed by surface plasmon resonance enhanced ellipsometry (SPREE). However, the proximity of the inorganic support did not provide the space for the insertion of transmembrane proteins. The second approach, based on skeletonized surfaces as support for lipid bilayers, proved to be successful in the insertion of two proteins, integrin and BK channel. The immobilized proteins were shown to be functional and stable in lipid bilayers supported on skeletonized surfaces. Our findings provided then evidences that the model based on skeletonized surfaces behaved as natural membrane.;Another model was developed to immobilize histagged proteins on zirconium phosphonate surfaces via synthetic linkers. The binding and activity of histagged proteins were studied and the results showed that proteins adsorbed in a functional conformation on the surface with high density. These linkers have thus the potential to be used in proteins microarrays. Also, zirconium phosphonate surface was used as an enrichment matrix for phosphorylated peptides. SPREE was employed to demonstrate the capability of the latter surface and to understand binding affinity of different peptides.;The design, surface morphology, stability and characterization of the model systems were analyzed by complementary biophysical techniques. In this work, SPREE and ellipsometry provided insightful details on the kinetic binding, self-assembly monolayer formation and stability of the biosensors. Other techniques such as atomic force microscopy (AFM), x-ray photoelectron spectroscopy (XPS) and confocal fluorescence microscopy were used to characterize the morphology of modified surface and the formation of supported lipid bilayers. |
