Preparation of 3D porous cellulose‐chitosan hybrid gel macrospheres by alkaline urea system for enzyme immobilization

Abstract

In order to find a low-cost, green and sustainable immobilized enzyme carrier, cellulose material has been widely used in the field of immobilized enzyme, but the low specific surface area and apparent porosity limit its further application. In this article, cellulose and chitosan are dissolved in alkaline urea system through freeze-thaw cycle, then regenerate in weakly alkaline by sol-gel method and solvent exchange. A novel 3D porous cellulose-chitosan hybrid gel macrospheres (CCMs) with high specific surface area (235.4-325.3 m 2 /g) are obtained after lyophilization. The cellulosechitosan macrospheres are characterized by Fourier transform infrared (FTIR) spectroscopy, thermogravimetric analysis (TGA), and X-ray diffractive analysis (XRD) and the size, surface, and internal morphology of CCMs are observed by scanning electron microscopy (SEM). Furthermore, it is found that α-amylase (AMY) could be successfully immobilized on the hybrid gel microspheres by glutaraldehyde regent.Compared with free α-amylases, immobilized enzymes exhibit higher thermal stability, more broadly pH adaptive, and improved storage stability. After 10 cycles, the immobilized enzymes retain 77.5% of their initial activity.

Enzyme Immobilization on a Delignified Bamboo Scaffold as a Green Hierarchical Bioreactor

“…This result implied the excellent efficiency of the immobilization method for delignified bamboo. As shown in Figure and Table S3, the protein loading capacity of the OBS (8.09 mg/m 2 ·g –1 ) is 3–20 times that of delignified wood and other cellulose-based supports with comparable or much bigger specific surface area. − Furthermore, when a high concentration of F-BSA (i.e., 1.0 mg/mL) was used, the protein loading was ∼6-fold that at low concentrations (0.1–0.4 mg/mL, Table S4 and Figure S6), indicating the diffusion rate as an important factor affecting the immobilization process. Similarly, when 1.0 mg/mL BGUs was used for immobilization, 4.4 ± 0.2 mg/g loading capacity was identified (Figure S7 and Table S4), which was close to the calculated theoretical capacity (4.8 mg/g, Table S4).…”

“…Comparison of immobilized efficiency versus specific surface area of different cellulose-based systems. − BSA (MW: 66.5 kDa) was used for the measurement in this work.…”

“…To date, both covalent and noncovalent strategies have been explored to immobilize enzymes on a cellulose scaffold and other solid supports. − Multiple types of interactions and multipoint interactions could occur during and after the protein immobilization, − which should be considered for the design of the immobilization method and process optimization. , The amine groups at the side chain of lysine residues and the N-terminal of the proteins are commonly used for enzyme immobilization since the majority of proteins have such amine groups on their surface, which are usually exposed to medium and accessible for derivatization . The amine group can react with the aldehyde group of the oxidized cellulose unit to form a Schiff base. , However, the Schiff base is not stable, while once reduced to the C–N bond, the formed alkylamine linkage is highly stable .…”