An investigation of factors associated with the preparation of immunomagnetic beads

Parameters affecting antibody conjugation with immunomagnetic beads (IMB) are investigated when Goat antiMouse IgG/HRP is used as a model antibody. Results found that antibody could be conjugated on the surface of magnetic beads (MB) by physiochemical adsorption and covalent bonds. The polystyrene/acrylamide magnetic beads (amino-MB) could bind more antibodies than polystyrene/acrylic acid magnetic beads (carboxyl-MB) when the concentration of antibodies ranged from 0.25 to 1.0mg/L. For amino-magnetic beads, the conjugation amount of antibodies increased gradually as the antibody to MB ratio increased from 5 to 20mg/g, while the value of antibodies kept stable when the ratio increased to 30 from 20mg/g. It is also found that the conjugation amount of antibodies increased rapidly in the first 1h and then kept unchanged the followed 1hr at the ratio of 20mg/g. There is a significant difference between conjunction amount of antibodies of IMB prepared with Tris buffer and Carbonate buffer solution (CBS). The maximal conjugation amount of antibodies on the amino-magnetic beads´ surface is 3.66mg/g when 2h incubation supplied with Tris buffer. The buffer also affects the dispersion of IMB. The dispersion of IMB prepared with CBS is better than that with Tris buffer before washing by TBST, while it is adverse after washing.