Aqueous electrolyte, interactions surfaces

Protems can be physisorbed or covalently attached to mica. Another method is to innnobilise and orient them by specific binding to receptor-fiinctionalized planar lipid bilayers supported on the mica sheets [15]. These surfaces are then brought into contact in an aqueous electrolyte solution, while the pH and the ionic strength are varied. Corresponding variations in the force-versus-distance curve allow conclusions about protein confomiation and interaction to be drawn [99]. The local electrostatic potential of protein-covered surfaces can hence be detemiined with an accuracy of 5 mV. 

Figure Bl.20.10. Typical force curve for a streptavidin surface interacting with a biotin surface in an aqueous electrolyte of controlled pH. This result demonstrates the power of specific protein interactions. Reproduced with pennission from [81].

The popular and well-studied primitive model is a degenerate case of the SPM with = 0, shown schematically in Figure (c). The restricted primitive model (RPM) refers to the case when the ions are of equal diameter. This model can realistically represent the packing of a molten salt in which no solvent is present. For an aqueous electrolyte, the primitive model does not treat the solvent molecules exphcitly and the number density of the electrolyte is umealistically low. For modeling nano-surface interactions, short-range interactions are important and the primitive model is expected not to give adequate account of confinement effects. For its simphcity, however, many theories [18-22] and simulation studies [23-25] have been made based on the primitive model for the bulk electrolyte. Ap-phcations to electrolyte interfaces have also been widely reported [26-30]. 

The experimental data bearing on the question of the effect of different metals and different crystal orientations on the properties of the metal-electrolyte interface have been discussed by Hamelin et al.27 The results of capacitance measurements for seven sp metals (Ag, Au, Cu, Zn, Pb, Sn, and Bi) in aqueous electrolytes are reviewed. The potential of zero charge is derived from the maximum of the capacitance. Subtracting the diffuse-layer capacitance, one derives the inner-layer capacitance, which, when plotted against surface charge, shows a maximum close to qM = 0. This maximum, which is almost independent of crystal orientation, is explained in terms of the reorientation of water molecules adjacent to the metal surface. Interaction of different faces of metal with water, ions, and organic molecules inside the outer Helmholtz plane are discussed, as well as adsorption. 

The interaction between bare mica surfaces in 0.1 M KNO3 (pH 5.5) aqueous electrolyte is shown in figure 6a. The straight line (curve (a)) indicated on the logarithmic-linear plot is in accord with the exponential relation... 

M.L. Fielden, R.A. Hayes, and J. Ralston Surface and Capillary Forces Affecting Air Bubble-Particle Interactions in Aqueous Electrolyte. Langmuir 12, 3721 (1996). 

The acidic or basic character of a semiconductor surface gives rise to interaction with or OH ions of an aqueous electrolyte ... 

The oxide redox energy levels for all elements except gold are cathodic to the redox level of the H2O/O2 couple. Gold, however, is an impractical component for compound semiconductors. All other compound semiconductors employed as electrolysis photoanodes will undergo surface oxidation in aqueous electrolytes to produce a surface oxide film which normally constitutes the stable surface of the photoelectrode. Our proposed mechanism indicates that the proton induced oxide dissolution reaction arises from product ir ion interactions with the oxide anion (0=). 

V at 40°. This AV. /pCl" value for the (100) orientation n-GaAs is approximately one-half that obtained with (111) n-GaAs crystals (2), indicating that the crystal surface atom density and type can be a significant factor in the interactions between substrate and electrolyte. Flat-band potential values for (100) and (111) n-GaAs/molten salt interphases and for the (111) n-GaAs/aqueous electrolyte interphase are compared in Table I. 

For measurements between crossed mica cylinders coated with phospholipid bilayers in water, see J. Marra andj. Israelachvili, "Direct measurements of forces between phosphatidylcholine and phosphatidylethanolamine bilayers in aqueous electrolyte solutions," Biochemistry, 24, 4608-18 (1985). Interpretation in terms of expressions for layered structures and the connection to direct measurements between bilayers in water is given in V. A. Parsegian, "Reconciliation of van der Waals force measurements between phosphatidylcholine bilayers in water and between bilayer-coated mica surfaces," Langmuir, 9, 3625-8 (1993). The bilayer-bilayer interactions are reported in E. A. Evans and M. Metcalfe, "Free energy potential for aggregation of giant, neutral lipid bilayer vesicles by van der Waals attraction," Biophys. J., 46, 423-6 (1984). 

No. Compound Electrode material Aqueous electrolyte AG ads solution (M) kcal mol 1 Estimated" orientation (charge on surface) Assumed interaction... 

The fundamental understanding of electrostatic interactions in aqueous media is still incomplete, particularly when the interacting surfaces are highly charged or the electrolyte in solution is not symmetric. However, since the pioneering work of Derjaguin, Landau, Verwey and Overbeek [1,2] some... 

We shall further consider the interaction between two flat plates immersed into an aqueous electrolyte solution with an emphasis on the dielectric colloid material. These dielectric plates bear the surface charge of a constant density. All these assumptions simplify the boundary conditions (33)-(36) sufficiently, yielding... 

Another important result is that the flatband potentials and therefore the position of the energy bands at the semiconductor surface contacting an aqueous electrolyte, are usually independent of any redox system added to the solution. Hence, the interaction between semiconductor and H2O determines the Helmholtz layer and the position... 

Israelachs ili, J. N. Pashley, R. M. (1984). Measurement of the hydrophilic interaction between two hydrophilic surfaces in aqueous electrolyte solutions. J. Colloid Interface Sci. 98,500-514. 

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