Ester synthesis using Candida rugosa lipase immobilized on magnetic nanoparticles

Magnetic nanoparticles were synthesized by co-precipitation under hydrothermal conditions. The average diameter of the magnetic nanoparticles was found to be in the range of 15 +/- 5 nm with an average surface area of 112.15 m(2) g(-1). Immobilization of lipase on magnetite nanoparticles was confirmed by FTIR, differential scanning calorimetry and thermal gravimetric analysis. The activation energy of the free enzyme was 1.9-fold higher than that of the immobilized lipase for hydrolytic reactions. Additionally, the lower K-M and higher V-max values of the immobilized enzyme for hydrolysis of 4-nitrophenyl palmitate indicated an increased efficiency of the immobilized lipase.The immobilized lipase exhibited higher esterification efficiency compared with free lipase for synthesis of ethyl isovalerate. It also exhibited fairly good reusability, with about 8.5% reduction in esterification efficiency for ethyl isovalerate synthesis over ten cycles of reuse.