Coating adsorption, passive

Figure 8. Calibration curve for HBsAg using the polystyrene cuvette coated by passive adsorption of anti-HBsAg and the conventional EIA The brackets denote the 0 ng/ml standard HBsAg.

Preparation of microtiter plates. A constant amount of the coating antigen is bound to the surface of polystyrene microtiter plate wells by passive adsorption. After a predetermined incubation time, the plate is washed to remove unbound coating antigen. 

Yields of EUPb are therefore constricted by adsorption and formation of passivating coatings, and rates are affected by side reactions of partially alkylated intermediates ... 

The adsorption of hydrocarbon molecules on Si surfaces is an interesting topic of study under various viewpoints. For example, a thin hydrocarbon film coating Si may be applied as a low dielectric in microelectronics and may passivate the surface if covalent bonds are formed between Si atoms and the adsorbate species. Further, unsaturated hydrocarbons play an important role as precursor species for chemical vapor deposition (CVD) of diamond - like films on the Si surface, and of silicon carbide (SiC). 

Usually, immobilization of antibodies can be performed either directly by passive adsorption, covalent coupling, or indirectly by using a solid surface pre-coated with protein A or G [25] or a secondary immunoglobulin (Ab2, anti-Abi) [26] for a favourable orientation of the antibody on the solid surfece with the binding sites towards the sample solution. This orientated immobilization of antibodies is important for the assay performance, taking into account the special characteristics of solid-phase immunoassays (see Section 9.3.4.4). 

Coating Buffer The first step in an ELISA is immobilization of the analyte antianalyte antibody on the microtiter plate. Immobilization occurs passively through van der Waals forces and hydrophobic interactions between the protein and the plastic surface. Proteins have minimum net charge and maximum hydrophobicity near their isoelectric points (IEPs) thus, a coating buffer with a pH close to the IEP of the protein aids in its adsorption to the plate. Unfortunately, information about the IEP of the protein may not be available. In such situations, one should evaluate the suitability of commonly used coating buffers such as lOOmM bicarbonate carbonate buffer (pH 8 10), 50mM PBS (pH -7.4), or 50 mM acetate buffer (pH 5) [17,18],... 

Sohds are exposed to the environment via their surfaces. Adsorption and reactions at the surface of various materials used in technology and everyday life are responsible for many important desired and undesired phenomena, including coating, passivation, corrosion, and heterogeneous catalysis. Surface interactions also offer a way to create novel advanced materials with tailored structural, electronic, magnetic and chemical properties. High-level quantum chemistry methods, together with the rich arsenal of experimental surface science techniques... 

Corrosion inhibitors are substances whose introduction in small amounts into a corrosion system (aggressive medium, polymer coating, lubricating or packing material, etc.) produces noticeable corrosion abatement in metals. Cl are subdivided into adsorption and passivating Cl by their action mechanism. The former protect metals by affecting the kinetics of the electrode corrosion processes. The latter promote the formation of an oxide or other films on a metal product to transfer the metal into the passive state. 

A key feature of the solid-phase ELISA is that antigens or antibodies can be attached to smfaces easily by passive adsorption. This proeess is commonly called coating. Most proteins adsorb to plastic smfaces, probably as a result of hydrophobie interactions between nonpolar protein substructures and the plastie matrix. The interactions are independent of the net charge of the protein, and thus each protein has a different binding constant. The hydrophobieity of the plastic/protein interaction can be e qjloited to increase binding since most of proteins hydrophilic residues are at the outside and most of the hydrophobic residues orientated towards the inside (1). 

Pratten MK, Duncan R, Lloyd JB. Adsorptive and passive pinocytic uptake. In Ockleford CJ, Wh3dn A, eds. Coated Vesicles. Cambridge Cambridge University Press, 1980 179-218. 

Hydrophilic coatings have also been popular because of their low interfacial tension in biological environments [Hoffman, 1981]. Hydrogels as well as various combinations of hydrophilic and hydrophobic monomers have been studied on the premise that there will be an optimum polar-dispersion force ratio which could be matched on the surfaces of the most passivating proteins. The passive surface may induce less clot formation. Polyethylene oxide coated surfaces have been found to resist protein adsorption and cell adhesion and have therefore been proposed as potential blood compatible coatings [Lee et al., 1990a]. General physical and chemical methods to modify the surfaces of polymeric biomaterials are listed in Table 40.7 [Ratner et al., 1996]. 

These equations assume equilibrium adsorption exists at the passive film interface. Island-type adsorption instead of the uniform adsorption assumed in these equations has also been suggested. The standard coating based on chromate conversion layers is used to protect high-strength A1 alloys. The primer may contain chromate pigments that enhance protection. The chromium protection mechanism is described by Edeleanu and Evans [89]. 

Electrochemical inhibitors retard or prevent the anodic and/or cathodic partial reactions (i.e they influence the reaction at the metal/corrosive medium interface). Chemical inhibitors can react both with the material and form protective coatings and with the medium itself or its constituents and thus diminish its aggressiveness. Physical inhibitors form adsorption layers on the metal surface, which block the corrosion reaction. Inhibitors that influence the electrochemical electrode reactions are subdivided according to their mode of action and site of action in the area of the metal/ medium phase boundary, with the subdivision being between interface inhibitors, electrolyte film inhibitors, membrane inhibitors, and passivators. 

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