The discovery of uniform latex particles by polymer chemists of the Dow Chemical Company nearly 50 years ago opened up new exciting fields for scientists and physicians and established many new biomedical applications. Many in vitro diagnostic tests such as the latex agglutination tests, analytical cell and phagocytosis tests have since become rou tine. They were all developed on the basis of small particles bound to biological active molecules and fluorescent and radioactive markers. Further developments are ongoing, with the focus now shifted to applications of polymer particles in the...