A two-step method for the synthesis of magnetic immobilized cellulase with outstanding thermal stability and reusability

Abstract

In order to make better use of cellulase, a simple and fast method using electrostatic attraction and silica embedment was proposed for enzyme immobilization. Firstly, cellulase was adsorbed on the surface of support material Fe₃O₄@C to achieve the preliminary fixation at pH 5.5. Then the embedment of cellulase was achieved in 1 h by forming a thin silica shell. The loading capacity of cellulase can reach 200 mg g⁻¹. The immobilized cellulase was characterized by various methods, such as FT-IR, TGA, SEM, TEM and surface Zeta potential measurement. The thermal and recycling stability of the as-prepared Fe₃O₄@C@cellulase-SiO₂ can be greatly enhanced by the protection of the thin silica shell. The relative activity of immobilized cellulase can be maintained at more than 80% after 30 minutes at 80 °C. At the same time, due to the influence of silica embedment, the immobilized cellulase can still maintain about 80% relative activity after 9 times of reuse. The stability assays show that the immobilized cellulase exhibits higher reusability, thermal stability and storage stability compared with free cellulase.