Synthesis of superparamagnetic carboxymethyl chitosan/sodium alginate nanosphere and its application for immobilizing α-amylase

• Nano Fe3O4/CMC/SA can exert the advantages of nano Fe3O4 and SA. It has an important research value for immobilized enzyme.
• In this study, α-amylase was selected as a simulation object to manufacture an immobilized enzyme (SM/CMC/CA/α-Amy).
• Immobilization increased 4.67 times to catalytic activity, slowed down release rate and improved reusable performance.
• The stabilities of pH, thermal and storage for SM/CMC/CA/α-Amy were improved remarkably.
• All these results indicated that SM/CMC/SA was an ideal carrier for immobilizing enzyme.

In order to improve catalytic activity, increase recycling times, reduce use cost for enzyme, superparamagnetic carboxymethyl chitosan/sodium alginate nanosphere (SM/CMC/SA) has been synthesized via an improved hydrothermal method, molecular self-assembly technology, electrostatic interaction and amide linkage. Its mean diameter was 65 nm, zeta potential was −36.9 mV and BET was 53.8 m2/g. α-Amylase was selected as a simulation object to manufacture an immobilized enzyme (SM/CMC/CA/α-Amy), and its catalytic activity, release behavior, reusability and stability were researched. Immobilization increased 4.67 times to catalytic activity, slowed down release rate and improved reusable performance. SM/CMC/CA/α-Amy showed higher activity over a wider pH range, especially in strong acidic and alkaline environments. The thermal stability and storage stability were improved remarkably too. All these results indicated that SM/CMC/SA was an ideal carrier for immobilizing enzyme.