Immobilization of laccase onto functionalized ionic liquid-modified mesoporous silica SBA-15

Abstract

The enzyme’s immobilization from different sources on various supports can increase the stability of the enzyme. In addition, immobilization can decrease the cost of separation and facilities the reuse of the enzymes. Therefore, the design of new immobilization enzyme supports has become a popular field in modern biotechnology. Here, we prepared a series of functionalized ionic liquid (FIL) supports and successfully grafted onto the mesoporous molecular sieve (SBA-15). According to the cation C1 group and the anion X– (BF4 and PF6) in the imidazole group of the FIL, the FIL was represented by C1/BF4 and C1/PF6, etc. A new FIL modified mesoporous molecular sieve was obtained (FIL-SBA-15: C1/BF4-SBA-15 and C1/PF6-SBA-15), and it was proved by Fourier transform infra-red (FTIR) spectroscopy, scanning electron microscope (SEM) and X-ray diffraction (XRD). Then laccase was immobilized on FIL-SBA-15 by adsorption to obtain a series of more stable and active laccase preparations, of which laccase-C1/BF4-SBA-15 performed best. The higher activity of the laccase-C1/BF4-SBA-15 occurred under a wider pH range of 6.0–8.0 and the laccase activity remains 75% at 85 °C. It was also recyclable and could maintain 85% of its initial activity after reusing it four times. These results showed that the catalytic performance of laccase had improved significantly by immobilization on the laccase-C1/BF4-SBA-15.