A novel method for the immobilization of urease on phosphonate grafted iron oxide nanoparticle

The development of simple and reliable technique for the immobilization of enzymes is an important part of biotechnology. We demonstrate herein the modification of magnetic nanoparticles and its use in the immobilization of the urease enzyme. Magnetite particles were prepared by simple co-precipitation method in aqueous medium and then subsequently coated with phosphonomethyl iminodiacetic acid. Urease was immobilized on the magnetic nanoparticles through a carbodiimide reaction. Surface functional groups and surface composition were analyzed by Fourier transform infrared (FTIR) spectroscopy and thermo gravimetric analysis (TGA), respectively. The structural characteristics of the powders were studied by XRD. These modified nanoparticles were characterized by dynamic light scattering (DLS) and high resolution transmission electron microscopy (HRTEM). Vibration sample magnetometry (VSM) measurements showed the superparamagnetic nature of the particles at room temperature. The catalytic activity of the immobilized urease was comparable to that of the free enzyme in solution. The immobilized urease exhibited excellent catalytic activity over six times successive reuse as well as the stability. By using immobilization technique on this magnetic nanoparticle it is easy to isolate product from reaction mixture enabling to control the reaction and simultaneously lowers the cost of enzyme. (C) 2011 Elsevier B.V. All rights reserved.