Immobilization of lipase on magnetic nanoparticles and magnetic nanocomposites for application in biotransformation reaction

Magnetic nanoparticles (Fe₃O₄) were synthesized by co-precipitation from a solution of di and trivalent iron ions (molar ratio 1:2). The particles were characterized by Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FTIR) and X-ray Diffraction  (DRX). Burkholderia cepacia lipase was immobilized onto support synthesized using two different methods of immobilization physical adsorption and covalent binding on nanoparticles silanized with 3-aminopropyltriethoxysilane and activated with glutaraldehyde. Immobilized biocatalyst was used in the hydrolysis reaction of olive oil for evaluation of yield immobilization and operational stability. The lipase immobilized onto magnetic nanoparticles by physical adsorption and covalent binding showed a yield of immobilization of 86.14% and 97.48%, respectively. The lipase immobilized by physical adsorption presented an operational stability of seven cycles, while the fixed by covalent presented nine cycles. Magnetic chitosan nanocomposites were synthesized by addition of the gel of chitosan (5 or 10%) obtaining an average yield of immobilization by physical adsorption of 93.09%, while by covalent binding, if obtained an average yield of 90.95%. The immobilized lipase in 5% chitosan by physical adsorption and covalent binding, showed stable operation for nine cycles each. While the immobilized lipase in 10% of chitosan by physical adsorption, presented an operational stability of 6 cycles while the immobilization by covalent presented seven cycles. The SEM was applied to analyses the morphology of the nanocomposite, FTIR showed the higher absorption bands and by DRX it was possible to estimate the crystallite size of the particles of 8.23 nm and magnetization curve of 57.49 emμ/g.