Suo_2019_Mater.Sci.Eng.C.Mater.Biol.Appl_96_356

We developed magnetic chitosan nanoparticles (CSFe3O4) with mean diameter of 15-20nm. Subsequently, these inorganic-organic composite nanoparticles were modified using an imidazole-based functional ionic liquid (IL). The prepared support (ILCSFe3O4), which was used to immobilize porcine pancreatic lipase (PPL), was characterized using Fourier transform infrared (FTIR) spectroscopy, vibrating sample magnetometry (VSM), thermogravimetry (TG), transmission electron microscopy (TEM) and X-ray diffraction (XRD). Circular dichroism (CD) was used to analyze the secondary structure of immobilized PPL. The immobilized PPL (PPLILCSFe3O4) exhibited 1.93-fold higher specific activity than PPLCS-Fe3O4 when triacetin was used as the substrate, and showed 95mg/g of lipase immobilization capacity and 382% of activity recovery. The residual activity of PPLILCSFe3O4 was above 60% of the initial activity after incubation at 50 degrees C for 6h, as was higher than that of PPLCSFe3O4 which showed 40% of the initial activity. In addition, PPLILCSFe3O4 retained 84.6% of the initial activity after 10cycles, whereas PPLCSFe3O4 retained only 75.5% activity. Furthermore, the kinetic parameters, apparent Km and Vmax of PPLILCSFe3O4 were 2.51mg/mL and 1.395U/mg respectively, these results indicated that the immobilized PPL had better affinity towards the substrate, especially when the nanoparticles were modified by functional IL. Besides, the magnetic chitosan nanoparticles loaded with PPL were easily recovered. A novel, efficient, and practical method for enzyme immobilization was developed.