Fe3O4@SiO2 nanocomposite immobilized with cellulase enzyme: Stability determination and biological activity

The preparation of biocatalysts based on immobilized cellulase is of great importance for proteomic research, industrial applications, and organic synthesis. Herein, Fe3O4 magnetic nanoparticles were synthesized by the coprecipitation method to immobilize the cellulase enzyme and modified to increase its efficiency and stability. Hence, Fe3O4 MNPs were coated with silica by the Stober method, and the surface of Fe3O4@SiO2 nanocomposite was modified with an organosilane. To prevent surface adhesion, the nanocomposite was modified by APTES, and TCT was used as a linker for the immobilization of cellulase. The cellulase enzyme was covalently bonded to the nanocomposite via physical adsorption to synthesize cellulose-Fe3O4@SiO2-NH2 NC and increase its activity and stability. The maximum immobilization of the enzyme occurred at pH = 5, which was close to the isoelectric pH, and the optimum time and temperature for enzyme activity were 1 h and 50 °C. The binding efficiency was around 99 % by using the Bradford method. The maximum activity of the enzyme calculated by the CMC method was 0.08 μmol/min.ml. The adsorption capacity of immobilized cellulase was 33 mg/g toward bovine serum albumin (BSA). The results indicated that the activity and stability of the immobilized enzyme were enhanced in comparison with the free enzyme.