Immobilization of Cellulase onto Core-Shell Magnetic Gold Nanoparticles Functionalized by Aspartic Acid and Determination of its Activity.

New support was fabricated to enhance the enzyme activity of cellulase following immobilization. Functionalized core-shell magnetic gold nanoparticles were prepared and characterized by X-ray diffraction (XRD), vibrating sample magnetometer (VSM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Cellulase enzyme was immobilized on support via covalent bonding. The successful binding of the enzyme was chemically confirmed by Fourier-transform infrared spectroscopy (FTIR). The binding efficiency was 84% determined by Bradford assay. Filter Paper Activity (FPase) method was used to measure the enzyme activity at different temperatures (35-75 °C) and pH (2-8). The immobilized cellulase maintained 73% of its initial catalytic activity after 9 h and its activity is 0.78 mmol.ml-1. The newly designed nano-system also enhanced the thermal stability of immobilized cellulase in comparison to free cellulase and facilitated its long term storage.