A Facile Preparation Process of Magnetic Aldehyde-Functionalized Ni(0.5)Zn(0.5)Fe₂O4@SiO₂ Nanocomposites for Immobilization of Penicillin G Acylase (PGA).

A facile sol combustion and gel calcination process has been reported for the preparation of core– shell magnetic Zn0.5Fe₂O₄@SiOnanocomposites. The morphology, chemical composition, structure and magnetic property of as-prepared nanocomposites were investigated by XRD, VSM, BET, SEM, and TEM, and the magnetic Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites were characterized with average size of about 25 nm, saturation magnetization of 90.8 Am²/kg and the specific surface area of 67.1 m2/g. The surface of Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites was functionalized with glutaraldehyde to form the aldehyde-functionalized magnetic Ni0.5Zn0.5Fe₂O4@SiO₂ nanocomposites, and penicillin G acylase (PGA) was successfully immobilized onto them. And the immobilized PGA exhibited high effective activity, good stability of enzyme catalyst and good reusability, and could retain 63.5% of initial activity after 12 consecutive operations. The kinetic parameters were determined, and the value of K m for the immobilized PGA (161.7 mmol/L) is higher than that of the free PGA (3.5 mmol/L), while v max (1.626 mmol/min) is also larger than that of the free PGA (0.838 mmol/min), which revealed that the immobilization of PGA onto Ni0.5Zn0.5Fe₂O₄@SiO₂ nanocomposites was an efficient and simple way for preparation of stable PGA.