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M Stenberg

Publications and source records attributed to M Stenberg.

28 records · Page 2Linked to original sources
PubMed1982

Diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA). Quantification of antigen by diffusion over an antibody-coated surface.

The diffusion-in-gel enzyme-linked immunosorbent assay (DIG-ELISA) has previously been used for quantification of antibodies. In the present study, using bovine serum albumin as antigen and a corresponding rabbit antiserum as antibody source, the DIG-ELISA principle was used for quantification of antigen. Antibodies were immobilized on a plastic surface, over which the antigen was allowed to diffuse in an agarose gel. The antigen-antibody reaction zones were then detected by binding of an enzyme-labelled antibody directed against the antigen. The enzyme-substrate reaction, yielding a coloured reaction product, was visualized in a substrate-containing gel. The density and quality of immobilized antibody on the surface was found to be critical. Reproducible results were obtained only when antibodies purified with affinity chromatography on immobilized antigen were used. After 46 h of diffusion the diameter of the reaction zones was directly proportional to the logarithm of the antigen concentration in the range 0.4 mg/1-1 g/1. The variability of the method (CV) was 3%.

Animals↗
PubMed1981

Biospecific bimolecular binding reactions - a new ellipsometric method for their detection, quantification and characterization.

A new ellipsometric method for detection, quantification and characterization of bimolecular, specific interactions on solid surfaces, e.g., binding between antigen and antibody and between ligand and receptor, is described. In the method, which we have called diffusion-in-gel (DIG) ellipsometry, one of the binding components is placed in a trough in a gel which has been poured over a solid surface coated with the other binding component. After diffusion, the gel is removed from the surface and ellipsometric measurement of thickness of adsorbed bimolecular layers is performed at different distances from the site of the diffusion trough. Bimolecular binding on the solid surfaces was also studied by wettability determinations with a water condensation technique. Three bimolecular binding systems were studied: bovine serum albumin (BSA)-anti-BSA, ganglioside GM1-cholera toxin, and C-polysaccharide-C-reactive protein. There was no tendency to saturation in the anti-BSA adsorption profile, which was steep with an endpoint thickness of about 16 nm. In contrast, the cholera toxin profile, within a narrow concentration range, rose to a plateau level of about 3 nm thickness of adsorbed cholera toxin. The C-reactive protein profile formed an intermediate pattern. Good agreement was observed between the thickness of the adsorbed ligand layers and wettability as determined by water condensation. Compared with other methods, the DIG ellipsometry technique has several theoretical and practical advantages for the detection and investigation of biospecific bimolecular binding.

Adsorption↗
PubMed1979

The isoelectric point of thrombin and its behaviour compared to prothrombin at some solid surfaces.

We have shown that the isoelectric point of thrombin is high and that thrombin is a cation at the pH of blood. On the other hand, prothrombin has a low isoelectric point, being more anionic at the pH of blood. It was also found that thrombin adsorbs readily to surfaces, especially negatively charged surfaces, like behenic acid surfaces at pH 8.2. Furthermore, thrombin adsorbed onto behenic acid was active in the sense that it coagulated fibrinogen. The significance of the electric charge of the thrombin molecule in the mechanism of atherosclerosis is discussed.

Adsorption↗