Characterization of antibody labelled colloidal gold particles and their applicability in a sol particle immuno assay (SPIA).

This study describes the characterization of antibody labelled colloidal gold particles and their applicability in a sol particle immuno assay (SPIA) to quantify murine monoclonal antibodies of all IgG isotypes. Two physical methods (transmission electron microscopy (TEM) and dynamic light scattering (DLS], were used to obtain information about particle size and morphology of the gold sols, but only with DLS antibody labelling could be detected. In addition, electrophoretic methods like agarose electrophoresis and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) showed also that antibody labelling was successful. The biological activity of the antibody gold conjugates was determined by using them in a SPIA and as an electrondense marker in an immunogold labelling procedure to visualize meningococcal surface exposed outer membrane proteins labelled with monoclonal antibodies. The SPIA was applicable to determine murine monoclonal antibodies of all IgG isotypes with a sensitivity of 20-80 ng/ml and a coëfficiënt of variation of 6.7 +/- 2.2%.