Electrostatic interactions of surfaces

Heller, J. and Heller, A. Loss of activity or gain in stability of oxidases upon their immobilization in hydrated silica significance of the electrostatic interactions of surface arginine residues at the entrances of the reaction channels. J. Am. Chem. Soc., 1998,120, 4586 1590. 

Significant advances have been made over the last three decades in our understanding of steric stabilization, and recently measurements have been reported on the force between two surfaces containing adsorbed polymer ". Data on the measurement of the force due to the electrostatic interaction of surfaces have also been presented, as well as those arising from non-DLVO interactions. 

Paschual-Ahuir J L, E Silla, J Tomasi and R Bonaccorsi 1987. Electrostatic Interaction of a Solute with a Continuum. Improved Description of the Cavity and of the Surface Cavity Bound Charge Distribution. Journal of Computational Chemistry 8 778-787. 

The deposition-reduction (DR) method is based on the weak electrostatic interactions of polymer surfaces with the oppositely charged Au(III) complex ions, leading to the reduction of Au(III) exclusively on the polymer surfaces. Appropriate anionic or cationic Au(III) precursors are chosen based on the zeta potentials of polymer supports (Figure 3.6) [43]. 

The stability of colloids can also be dramatically altered by inclusion of polymeric materials. If the polymer interacts favourably with the particle surfaces, i.e. it adsorbs, then both an increase and a reduction in stability is possible, via modification of the electrostatic interaction of the polymer is charged or a reduction in the van der Waals attraction. 

The control parameter in an STM, the current in the tunneling junction, is always due to the same physical process. An electron in one lead of the junction has a nonvanishing probability to pass the potential barrier between the two sides and to tunnel into the other lead. However, this process is highly influenced by (i) the distance between the leads, (ii) the chemical composition of the surface and tip, (iii) the electronic structure of both the systems, (iv) the chemical interactions between the surface and the tip atoms, (v) the electrostatic interactions of the sample and tip. The main problem, from a theoretical point of view, is that the order of importance of all these effects depends generally on the distance and therefore on the tunneling conditions [5-8]. 

HTAC cationic micelles also markedly enhance the CL intensity of fluorescein (FL) in the oxidation of hydrogen peroxide catalyzed by horseradish peroxidase (HRP) [39], However, no CL enhancement was observed when anionic micelles of sodium dodecyl sulphate (SDS) or nonionic micelles of polyoxyethylene (23) dodecanol (Brij-35) were used (Fig. 9). CL enhancement is attributed to the electrostatic interaction of the anionic fluorescein with the HTAC micelles. The local concentration of fluorescein on the surface of the micelle increases the efficiency of the energy transferred from the singlet oxygen (which is produced in the peroxidation catalyzed by the HRP) to fluorescein. This chemiluminescent enhancement was applied to the determination of traces of hydrogen peroxide. The detection limit was three times smaller than that obtained in aqueous solution. 

Surface adsorption. Foreign ions are kept in a diffuse sheet at the surface of the crystal, as a result of electrostatic interaction with surface atoms whose bonds are not completely saturated. 

The immobibzation of NAs onto these membranes is usually achieved through electrostatic interactions of the NA and surface under chaotropic conditions. However, chemical activation of the membrane by silanization is also possible and would allow covalent linkage of NAs to the support surface. 

The immobilisation by electrostatic interactions of longer, 26 bp ssDNA strands on hard, poly(lysine)-coated glass resulted in aggregates of 63 nm (Fig. 26) [163]. Finally, when DNA molecules of the same length (26 bp) were covalently immobilised on the surface of plasma-induced, NHS-... 

The phosphate backbone of DNA molecules often results in undesirable electrostatic interactions with the substrate. Although the electrostatic interactions of DNA can be utilized for physical adsorption of DNA to the surface, this process can also lead to the nonspecific physical adsorption of target DNA on the surface. Rather than sample DNA hybridizing to the probe, it can adsorb to the surface and lead to interferences with the final detection call. Nonspecific adsorption effects have primarily been examined by the microarray community. Blocking strategies have been developed to prevent these nonspecific interactions. Succinic anhydride (SA) and bovine serum albumin (BSA) are two common methods to prevent nonspecific adsorption on amine modified surfaces. Blocking strategies are desired to react with or pas-... 

Interactions between the solutes and the capillary wall also have a negative effect on the efficiency in capillary zone electrophoresis. Both hydrophobic interactions and electrostatic interactions of cations with the negatively charged capillary wall can be the cause of solute adsorption. Significant adsorption has been found for high-molecular-weight species, e.g., peptides and proteins. Because of the increased surface-area-to-volume ratio of narrow-bore capillaries, this effect is even more pronounced. 

As the ionic strength increases, the Debye screening length decreases, resulting in interparticle electrostatic interactions of shorter range. The theoretical surface potential can be further related to the net protein charge Q (Home et al, 2007) ... 

The third factor, ZR, in Eq. (5.1) is called the residual contribution in the chemical engineering notation and it arises from all kinds of non-steric interactions between molecules, i.e., usually from vdW, electrostatic, and hydrogen bond interactions. Despite its name, it is the most important contribution in most liquids. The basic assumption of surface-pair interaction models is that residual—i.e., non-steric—interactions can be described as local pairwise interactions of surface segments. The residual contribution is just the partition sum of an ensemble of pairwise interacting surface segments. 

The mutual polarization process between the solute and the polarizable medium is obtained by solving a system of two coupled equations, i.e., the QM Schrodinger equation for the solute in presence of the polarized dielectric, and the electrostatic Poisson equation for the dielectric medium in presence of the charge distribution (electrons and nuclei) of the solute. The solute occupies a molecular shaped cavity within the dielectric continuum, whose polarization is represented by an apparent surface charge (ASC) density spread on the cavity surface. The solute-solvent interaction is then represented by a QM operator, the solvent reaction potential operator, Va, corresponding to the electrostatic interaction of the solute electrons and nuclei with the ASC density of the solvent. 

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