Synthesis of Biohybrid Material Based on Magnetic Zn–Al Hydrotalcite and Cellulase: Structural and Enzymatic Activity Characterizations

Abstract

Magnetic Zn–Al hydrotalcite (mHT) was synthesized by co-precipitation of Zn²⁺/Al³⁺ salt mixture in the presence of Fe₃O₄. mHT nanomaterials were characterized by Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray diffraction, vibrating-sample magnetometer, and nitrogen adsorption isotherm. Then, mHT was used as support for immobilizing cellulase under an adsorption mechanism to form cell@mHT. The effect of pH, cellulase concentration, the amount of mHT, and immobilization time on the immobilization of cellulase onto mHT were carefully investigated. The enzyme activity of both free cellulase and cell@mHT as well as immobilization efficiency, was analyzed by determination of reduced glucose using DNS as a color indicator. The immobilization process obtained the highest loading efficiency with 99.0% when carried out at pH 5, with a cellulase concentration of 0.1 mg/ml and using 0.1 g of mHT. Cell@mHT shows good enzyme activity when reacting with 1 mass% CMC solution at 50°C after 45 minutes with relative enzyme activity of 80.8%.

Fig. 6 Effect of pH (a) and temperature (b) of the reaction medium on the activity of free cellulase and cell@HT.