Application of novel chromium dioxide magnetic particles to immunoassay development.

We have used chromium dioxide magnetic particles as the solid support in developing a series of immunological tests. The high surface area (greater than 40 m2/g) available on the magnetic particles and their easy dispersion throughout a solution allow for rapid and complete capture of the target antigen. The magnetic responsiveness of the particles allows for rapid, high-efficiency washing to reduce nonspecific binding, which often limits the sensitivity of serological assays.

Determination of relative antigen-antibody affinities by quantitative immunoelectrophoresis.

The relative affinities of an antibody population of different antigens or of different antibody populations for one antigen can be determined by quantitative immunoelectrophoresis. Antigen-antibody interactions of greater average affinity result in a greater increase in rocket area as a function of the amount of antigen applied to the wells. This is measured as the slope of the line in plots of rocket area versus antigen amount.