Study on Improving the Stability of Adsorption-Encapsulation Immobilized Laccase@ZIF-67

Abstract Laccase (Trametes versicolor) was immobilized onto/into zeolite imidazolate framework-67 (ZIF-67) for the first time, materials were performed by assisting one-pot synthesis strategy in aqueous solution at room temperature. The resulting laccase@ZIF-67 composite was characterized by powder X-ray diffraction (PXRD), fourier transform infrared (FT-IR) spectroscopies, field emission scanning electron microscopy (FE-SEM) and energy dispersive X-ray (EDX), thermal gravimetric analyses (TGA). The results showed that laccase could be well immobilized on ZIF-67 materials. Laccase@ZIF-67 was stable on storage stability and reuseablility, retaining 88 % (15 days at 4 °C) and 59% (five reaction cycles) of residual enzyme activity. Laccase@ZIF-67 exhibited relatively stable activity at pH 3 to 5. In addition, the thermal deactivation kinetic studies of laccase@ZIF-67 showed a lower k value, higher t1/2 and ΔG values along with the enhancement of thermodynamic parameters than that of free laccase, and laccase@ZIF-67 had excellent level of thermostability.