Construction of Magnetic Nanoparticle–Enzyme Complexes with High Loading Efficiency by In Situ Embedding Iron Oxide into Enzymes

Novel Fe–enzyme complexes featuring magnetic nanoparticles (MNPs) embedded in/on enzymes in situ were fabricated for high-efficiency catalysis and separation. Fe(III) was immobilized on the inside or surface of an enzyme by metal coordination interactions and dopamine polymerization; after that, the MNPs were formed around Fe ions induced by aqueous NH3 solution. The as-prepared complexes could function as catalysts in their free state and then be separated and collected by a magnetic field after the catalytic reaction. The formation mechanism and catalytic activity of the complexes were investigated to evaluate their performance. The proposed strategy produces complexes mainly composed of the enzyme (ca. 77 wt %) and MNPs (ca. 23 wt %), and the preparation process is controllable under mild conditions to retain enzyme activity. The complex could effectively avoid the problem of steric hindrance encountered in the use of many carriers during catalysis, and the device space and mixing energy for mixing were further conserved for carrier weight inducement. This approach may open a facile and general way to prepare MNP–biomacromolecule complex with efficient load.