Immunoprecipitation & IgG purification: magnetic particles protein A magnetic silica particles contain high quality recombinant protein A covalently bound to the particle surface. These particles are available in 600 nm, 1.0 µm and 3.0 µm Protein A binds to the Fc regions of immunoglobulins. After binding onto a magnetic bead with a coating of protein A, immobilized immunoglobulins can be used for immunoprecipitation of various biomolecules, or can be eluted in a native or denaturated state. The magnetic particles with a mean size of 600 nm or 1.0 µm are best used for IgG purification and immunoprecipitation. The magnetic particles protein A particles with a mean diameter of 3.0 µm are especially suitable for cell capture research.