Motevalizadeh_2015_J.Mol.Catal.B.Enzym_120_75

In this study, polyethylenimine coated Fe3O4 magnetic nanoparticles (Fe@PEI) were prepared and used for three metal ions (Co2+, Cu2+ and Pd2+) chelation. The metal chelated magnetic nanoparticles (Fe@PEI-M) were characterized by using different spectroscopic and analytical techniques. The metal contents were analyzed by inductively coupled plasma atomic emission spectroscopy (ICP) and energy-dispersive X-ray spectroscopy (EDX). Thermomyces lanuginosa lipase (TLL) was then immobilized onto the modified magnetic supports by physical adsorption. Fe@PEI-Co and Fe@PEI-Cu showed better activity at extreme temperature and pH values than of the free enzyme. After 10 cycles of successful biocatalytic activity performed by immobilized lipase on Fe@PEI-Co, more than 60% of initial activity was reserved. Furthermore, the immobilized lipase onto Fe@PEI-Co retained about 80% of its initial activity after 14 days of storage. The immobilized lipase on the selected nanocomposite was then used for synthesis of ethyl valerate. After 24 h incubation time, the extent of esterification was found to be 70 and 60% in n-hexane and DMSO media, respectively.