Magnetic Amine-Functionalized ZIF-8 with Hierarchical Pores for Efficient Covalent Immobilization of α-Amylase

Abstract

The immobilization strategy between ZIF-8 and different enzymes has focused on in situ encapsulation and pore infiltration, while the surface attachment has been seldom reported because of less functional groups on the ZIF-8 surface. Here, a magnetic amine-functionalized ZIF-8 with hierarchical pores was designed for efficient covalent immobilization of α-amylase (α-Amy). By using Fe3O4 nanoparticles as the core and ZIF-8 as the shell, followed by Au3+–Zn2+ exchange reaction and β-mercaptoethylamine modification, the magnetic hollow ZIF-8 nanoparticle with amine groups on the surface was synthesized. With the assistance of glutaraldehyde, an α-Amy-magnetic hollow ZIF-8 composite was prepared and fully characterized by scanning electron microscopy, transmission electron microscopy, Fourier transform infrared spectrometry, X-ray photoelectron spectroscopy, energy-dispersive X-ray spectroscopy element mapping analysis, and vibration sample magnetometry. Then, the catalytic activity of immobilized α-Amy was explored with a K m of 2.307 mg/mL and V max of 0.506 mg/mL·min, indicating excellent catalytic activity. The study about stability and reusability demonstrated that the catalytic activity of immobilized α-Amy remained above 50% after 10 times of reuse. Thus, the designed magnetic amine-functionalized ZIF-8 was verified to be a nice carrier for covalent enzyme immobilization.

A Hydrophilic Metal Azolate Coordination Polymer for In Situ Encapsulation of Haloalkane Dehalogenase with Enhanced Enzymatic Performance

“…However, the fragile nature of enzymes (low stability at high temperature, poor tolerance to organic solvents, and difficulty in separation and reusability) increases cost and impairs catalytic effects, consequently limiting broader applications of the biocatalysts . A variety of approaches including chemical modification, cross-linking, and immobilization have been used to improve the catalytic performance of enzymes under harsh conditions. , In the past decade, metal–organic frameworks (MOFs), a class of materials that are synthesized via coordination between metal ions and organic ligands, have become a valuable platform for enzyme immobilization, − and some of the MOF-immobilized enzymes exhibited extraordinary stability as well as maintained the initial activity for multiple cycles. − …”