Immobilization of Enzymes on Magnetic Particles

Magnetic particles have been increasingly used as carriers for binding proteins, enzymes, and drugs. Such immobilization procedures for proteins, enzymes, antibodies, and other biologically active compounds have a major impact in different areas of biomedicine and biotechnology. The immobilized biomolecules can be used directly for a bioassay or as affinity ligands to capture or modify target molecules or cells. This chapter details immobilization procedures for proteins and enzymes onto various magnetically responsive carriers such as naked magnetic particles, carboxyl-modified microspheres, and aminomodified microspheres using direct binding procedure in the presence of coupling agents such as carbodiimide. The physical and chemical properties of freshly prepared magnetic particles were determined by magnetic measurements (VSM magnetometer), transmission electron microscopy (TEM), and atomic force microscopy (AFM). The extent of immobilization and enzyme activities were spectrophotometrically measured in order to find the retained activity after immobilization onto magnetic particles. The binding of proteins and enzymes was also confirmed by TEM microscopy.