Hydrophobic surface

The hydrophobic sensor chip HPA and the sensor chip L1 are used to capture lipid vesicles which differ in lipid composition and membrane receptors (proteins). After capturing analyte is injected and the interaction with the lipid membrane and/or receptor is monitored.

Besenicar, M. et al. Surface plasmon resonance in protein-membrane interactions. Chem.Phys.Lipids. 141: 169-178; (2006).

Recent advances in the preparation of stable membrane-like surfaces and the commercialisation of sensor chips has enabled widespread use of SPR in protein-membrane interactions. One of the most popular is Biacore's L1 sensor chip that allows capture of intact liposomes or even subcellular preparations. Lipid specificity of protein-membrane interactions can, therefore, be easily studied by manipulating the lipid composition of the immobilised membrane.

Woodward, J. T. and Meuse, C. W.. Mechanism of formation of vesicle fused phospholipid monolayers on alkanethiol self-assembled monolayer supports. J.Colloid Interface Sci. 334: 139-145; (2009).

We investigated the process of phospholipid vesicle fusion to a hydrophobic surface using electrochemical impedance spectroscopy (EIS) and atomic force microscopy (AFM). The kinetics of the fusion of dimyristoyl phosphatidylcholine (DMPC) vesicles to an octadecanethiol (ODT) self-assembled monolayer (SAM) was followed with EIS and found to be slower than previously reported observations by surface plasmon resonance.

Baird, C. L. et al. Surface plasmon resonance characterization of drug/liposome interactions. Analytical Biochemistry 310: 93-99; (2002).

Using Biacore's surface plasmon resonance-based biosensor technology, we developed experimental protocols and probed test conditions required to study drugs interacting with liposome surfaces. Liposome capture on hydrophobic alkane surfaces (Pioneer L1 chip) was reproducible and stable under variable conditions of pH, temperature, lipid content, cholesterol content, and buffer dimethylsulfoxide concentration.

Saenko, E. et al. Use of surface plasmon resonance for studies of protein-protein and protein-phospholipid membrane interactions. Application to the binding of factor VIII to von Willebrand factor and to phosphatidylserine- containing membranes. J.Chromatogr.A 852: 59-71; (1999).

In the present study two surface plasmon resonance-based binding assays permitting study of the interaction of coagulation factor VIII (fVIII) with von Willebrand factor (vWf) and phospholipid have been developed. With these binding assays, the role of the light chain (LCh) in fVIII binding to vWf and to immobilized phospholipid monolayers and intact vesicles containing 25% phosphatidylserine (PS) and 4% PS was examined.

Evans, S. V. and Roger, MacKenzie C.. Characterization of protein-glycolipid recognition at the membrane bilayer. J.Mol.Recognit. 12: 155-168; (1999).

A growing number of important molecular recognition events are being shown to involve the interactions between proteins and glycolipids. The lipid moiety is generally buried in the cell membrane or other bilayer, leaving the oligosaccharide moiety exposed but in close proximity to the bilayer surface. More recent studies have also shown that the composition of the lipid bilayer is a critical parameter in protein-glycolipid recognition. The fluidity of the bilayer allows for correct geometric positioning of the oligosaccharide head group relative to the binding sites on the protein.

Cooper, M. A. and Williams, D. H.. Kinetic analysis of antibody-antigen interactions at a supported lipid monolayer. Analytical Biochemistry 276: 36-47; (1999).

Modified phospholipids possessing carboxyl head groups synthesized from phosphatidylethanolamine were incorporated into supported lipid monolayers on top of a thin gold film. A monoclonal antibody was chemically coupled to the modified lipids in these monolayers and the kinetics of antigen binding were determined by surface plasmon resonance.

Cooper, M. A. et al. Surface plasmon resonance analysis at a supported lipid monolayer. Biochim.Biophys.Acta 1373: 101-111; (1998).

Methods for the formation of supported lipid monolayers on top of a hydrophobic self assembled monolayer in a surface plasmon resonance instrument are described. Small unilamellar vesicles absorb spontaneously to the surface of the hydrophobic self-assembled monolayer to form a surface which resembles the surface of a cellular membrane. Lipophilic ligands, such as small acylated peptides or glycosylphosphatidylinositol-anchored proteins, were inserted into the absorbed lipid and binding of analytes to these ligands was analysed by surface plasmon resonance.

Cooper, M. A. et al. A vesicle capture sensor chip for kinetic analysis of interactions with membrane bound receptors. Anal.Biochem 277: 196-205; (2000).

A vesicle capture sensor chip for kinetic analysis of interactions with membrane bound receptors.

Williams, C. et al. The L1 chip: Advances in lipid immobilization. Bia Journal 27-29; (2000).

The L1 chip: Advances in lipid immobilization

Hubbard, J. B. et al. Self assembly driven by hydrophobic interactions at alkanethiol monolayers: mechanisms of formation of hybrid bilayer membranes. Biophysical Chemistry 75: 163-176; (1998). Goto reference

The mechanism for the formation of biomimetic model cell membranes consisting of bilayers composed of alkanethiols and phospholipids was probed with a kinetic study using surface plasmon resonance. The kinetics of formation of a monolayer of phospholipid from vesicles in solution onto a hydrophobic alkanethiol monolayer is described by a model that takes into account the lipid concentration, diffusion, and a surface reorganization rate constant.