Synthesis of polyethyleneimine (PEI) andβ-cyclodextrin grafted PEI nanocomposites with magnetic cores for lipase immobilization and esterification

BACKGROUND Fabrication of nanocomposites with a magnetic core and their applications for enzyme immobilization has been introduced as an intresting trend during recent decades. The present study described the synthesis of polyethyleneimine (PEI) and β-cyclodextrin grafted PEI nanocomposites with magnetic cores and their applications for lipase immobilization. Fe3O4 magnetic nanoparticles (MNPs) were prepared by co-precipitation of Fe (III) and Fe (II) ions and then coated with polyethylenimine and/or hydroxyapatite/polyethylenimine, followed by grafting β-cyclodextrin onto the surface of the prepared nanocomposites. The nanocomposites were then characterized using Fourier transform infrared spectroscopy, X-ray diffraction, thermogravimetric analysis, vibrating sample magnetometry, and scanning and transmission electron microscopy and consequently applied for the immobilization of lipase. RESULTS The results obtained for thermal and pH stability, reusability, and storage stability showed that the MNPs@hydroxyapatite/polyethylenimine/β-cyclodextrin was the best nanocomposite for lipase immobilization. Application of the immobilized lipase onto the selected nanocomposite for the synthesis of ethyl valerate (green apple flavor) revealed esterification rates of 79% and 62% in n-hexane and dimethyl sulfoxide, respectively, after 24 h incubation. CONCLUSION The results obtained demonstrate good stability, reusability, and potential application of immobilized lipase on magnetic nanocomposite of MNPs@hydroxyapatite/polyethylenimine/β-cyclodextrin for synthesis of ethyl valerate especially in organic medium. © 2014 Society of Chemical Industry