Immobilization of Burkholderia cepacia lipase on functionalized ionic liquids modified mesoporous silica SBA-15

Mesoporous silica SBA-15 was modified by imidazole based ionic liquids (ILs) with various functional groups such as alkyl, amino, and carboxyl. Prepared supports (IL-SBA) were characterized by nitrogen adsorption-desorption (BET), small-angle X-ray diffraction (XRD), C-13 solid-state nuclear magnetic resonance (NMR), Fourier transform infrared (FTIR), elemental analysis, and scanning electron microscopy (SEM), transmission electron microscope (TEM), and applied to immobilize Burkholderia cepacia lipase (BCL). Results revealed that modification of mesoporous material SBA-15 with ILs was a novel and efficient method to improve the properties of immobilized BCL (BCL-IL-SBA). Improved thermal stability, reusability, storage stability and stability in organic solvent of BCL-IL-SBA were obtained. BCL-IL-SBA was also less sensitive to temperature and low pH than BCL-SBA-15. Moreover, BCL-IL-SBA showed relatively high specific activity, thereinto, BCL-NH2-IL-SBA had the highest specific activity, which improved 12.39-folds compared with BCL-SBA-15. Additionally, Michaelis-Menten constant Km and the initial maximum reaction velocity V-max of the immobilized BCLs were calculated by using Lineweaver-Burk plots and the results showed BCL-IL-SBA had better affinity towards the substrate. These improvements were associated with changes in pore structure and stronger enzyme support surface interactions. (C) 2012 Elsevier Ltd. All rights reserved.