An emotional contribution to the Festschrift of the Journal of Biomaterials Science for Teiji Tsuruta.

It is a honor for me to contribute to the 'Festschrift for Teiji Tsuruta'! Being old, it is much easier for me to look back than to think ahead. Thus, please allow me to make a few 'historical remarks' about Biomaterials and Biotechnology, long before Science stepped in. Remarks about Georg Christoph Lichtenberg, the Göttinger physicist and philosopher, and his relation to Teiji Tsuruta.

Force probe measurements of antibody-antigen interactions.

The surface force apparatus has been used to quantify directly the forces that govern the interactions between proteins and ligands. In this work, we describe the measured interactions between the antigen fluorescein and the Fab' fragment of the monoclonal 4-4-20 anti-fluorescyl IgG antibody. Here we first describe the use of the surface force apparatus to demonstrate directly the impact of the charge composition in the region of the antibody binding site on the antibody interactions.

Reduced protein adsorption on plastics via direct plasma deposition of triethylene glycol monoallyl ether.

The direct plasma-induced deposition of tri(ethylene glycol) monoallyl ether is reported. RF plasma polymerization of this monomer was carried out under both continuous wave (CW) and pulsed plasma operation. The major focus of this work was optimization of the degree of retention of the C-O-C bonds of the starting monomer during the deposition process.

Supramolecular assembly using helical peptides.

We investigated supramolecular assemblies of various hydrophobic helical peptides. The assemblies were formed at the air/water interface or in aqueous medium. The hexadecapeptide, Boc-(Ala-Aib)s-OMe (BA16M), was reported to take alpha-helical structure by X-ray analysis.

Neural cell pattern formation on glass and oxidized silicon surfaces modified with poly(N-isopropylacrylamide).

Control over the adsorption of proteins and over the adsorption and spatial orientation of mammalian cells onto surfaces has been achieved by modification of glass and other silicon oxide substrates with poly(N-isopropylacrylamide) (PNIPAM). The functionalization of the substrates was achieved either by a polymer-analogous reaction of aminosilanes with reactive N-(isopropylacrylamide) (NIPAM)-copolymers and by copolymerization of NIPAM with surface-bound methacrylsilane. The obtained coatings were characterized by FT-1R, ellipsometry, and surface plasmon resonance measurements.

4-4-20 anti-fluorescyl IgG Fab' recognition of membrane bound hapten: direct evidence for the role of protein and interfacial structure.

The surface forces apparatus was used to identify the molecular forces that control the interactions of monoclonal 4-4-20 antifluorescyl IgG Fab' fragments with fluorescein-presenting supported planar bilayers. At long range, the electrostatic force between oriented Fab' and fluorescein monolayers was controlled by the composition of the protein exterior surrounding the antigen-combining site rather than by the overall protein charge. The measured positive electrostatic potential of the Fab' monolayer at pH > pI(Fab') was consistent with the structure of the exposed Fab' surface in which a ring of positive charge at the mouth of the antigen-combining site dominates the local electrostatic surface properties.

Molecular mechanisms determining the strength of receptor-mediated intermembrane adhesion.

The strength of receptor-mediated cell adhesion is directly controlled by the mechanism of cohesive failure between the cell surface and underlying substrate. Unbinding can occur either at the locus of the specific bond or within the bilayer, which results in tearing the hydrophobic anchors from the membrane interior. In this work, the surface force apparatus has been used to investigate the relationship between the receptor-ligand bond affinities and the dominant mechanism of receptor-coupled membrane detachment.

Interaction of bombolitin III with phospholipid monolayers and liposomes and effect on the activity of phospholipase A2.

This study is focused on the characterization of the interaction of the amphiphilic peptide bombolitin III (from the bumblebee Megabombus pennsylvanicus) with phospholipid monolayers and vesicles. It is shown that due to the amphiphilic character of its alpha-helical conformation this water-soluble peptide is able to interact in an ordered fashion with phospholipid organized structures. Depending on the temperature, the subphase, and the particular phosphatidylcholine used, the mixed peptide-phospholipid monolayers can be homogeneous or display phase separation.

Investigation of specific binding of antifluorescyl antibody and Fab to fluorescein lipids in Langmuir-Blodgett deposited films using quartz crystal microbalance methodology.

Antifluorescyl IgG antibody and Fab binding to two fluorescein-conjugated lipids was measured using the quartz crystal microbalance methodology. By use of the Langmuir-Blodgett technique, the fluorescein lipids, which were diluted to 5% in a L-alpha-dipalmitoyl phosphatidylethanolamine (DPPE) matrix, were deposited directly onto one gold electrode of the quartz crystal. Binding to films containing the fluorescein hapten was significantly enhanced compared to films of the pure DPPE matrix lipid, indicating that binding occurred primarily through a specific interaction.

Formation of protein multilayers and their competitive replacement based on self-assembled biotinylated phospholipids.

Based on specific recognition processes the build-up of protein multilayers was achieved using streptavidin layers as a docking matrix. For this purpose, streptavidin was organized at biotin-containing monolayers, liposomes, and self-assembled layers on gold. Thus, mixed double and triple layers of streptavidin, Con A, Fab fragments, and hormones were prepared and characterized by fluorescence microscopy and plasmon spectroscopy.

Interactions of liposomes and hydrophobically-modified poly-(N-isopropylacrylamides): an attempt to model the cytoskeleton.

The interactions of small unilamellar vesicles (SUV) and water-soluble copolymers were studied by fluorescence spectroscopy, differential scanning calorimetry (DSC) and quasi-elastic light scattering (QELS). The anchoring onto liposomal bilayer membranes of copolymers of N-isopropylacrylamide, N-(2-(1-naphthyl)ethyl)-N-n-octadecylacrylamide and or N-[4-(1-pyrenyl)butyl]-N-n-octadecylacrylamide (0.5 mol% of the octadecylacrylamide comonomer) was monitored by non-radiative energy transfer between excited naphthalene and pyrene.

Attempts to mimic docking processes of the immune system: recognition-induced formation of protein multilayers.

The assemblage of protein multilayers induced by molecular recognition, as seen, for example, in the immune cascade, has been mimicked by using streptavidin as a docking matrix. For these experiments, this protein matrix was organized on liposomes, monolayers at the air-water interface, and self-assembled layers on gold, all three containing biotin lipids. The docking of streptavidin to biotin at liposomal surfaces was confirmed by circular dichroism.

Domain structures in langmuir-blodgett films investigated by atomic force microscopy.

Investigations of phase-separated Langmuir-Blodgett films by atomic force microscopy reveal that on a scale of 30 to 200 micrometers, these images resemble those observed by fluorescence microscopy. Fine structures (less than 1 micrometer) within the stearic acid domains were observed, which cannot be seen by conventional optical microscopic techniques. By applying the force modulation technique, it was found that the elastic properties of the domains in the liquid condensed phase and grains observed within the liquid expanded phase were comparable.

Quenching of fluorescein-conjugated lipids by antibodies. Quantitative recognition and binding of lipid-bound haptens in biomembrane models, formation of two-dimensional protein domains and molecular dynamics simulations.

Three model biomembrane systems, monolayers, micelles, and vesicles, have been used to study the influence of chemical and physical variables of hapten presentation at membrane interfaces on antibody binding. Hapten recognition and binding were monitored for the anti-fluorescein monoclonal antibody 4-4-20 generated against the hapten, fluorescein, in these membrane models as a function of fluorescein-conjugated lipid architecture. Specific recognition and binding in this system are conveniently monitored by quenching of fluorescein emission upon penetration of fluorescein into the antibody's active site.

Spontaneous domain formation of phospholipase A2 at interfaces: fluorescence microscopy of the interaction of phospholipase A2 with mixed monolayers of lecithin, lysolecithin and fatty acid.

Fluorescence microscopy has recently been proven to be an ideal tool to investigate the specific interaction of phospholipase A2 with oriented substrate monolayers. Using a dual labeling technique, it could be shown that phospholipase A2 can specifically attack and hydrolyze solid analogous L-alpha-DPPC domains. After a critical extent of monolayer hydrolysis the enzyme itself starts to aggregate forming regular shaped protein domains (Grainger et al.