Study on the Preparation of the AOPAN/MMT Composite Nanofibers and Their Application for Laccase Immobilization

Abstract

In this paper, a novel nano-material was prepared, and then was applied for enzyme immobilization. Amidoxime ployarcylonitrile /montmorillonite (AOPAN/MMT) composite nanofibrous membranes were generated by electrospinning and amidoxime modification, then the nanofiber membranes were modified by glutaraldehyde; the modified AOPAN/MMT composite nanofibers were applied in laccase immobilization by adsorption and crosslinking method. Scanning electron microscopy was used to visualize the morphology of the nanofibers, and Fourier transform infrared spectroscopy was used to provide information on the surface chemistry of original and modified nanofibers. At the same time, the optimization of immobilization conditions and the relative properties of the immobilized laccase were also studied in this thesis. According to the experimental results the optimum conditions of laccase immobilization were obtained: glutaraldehyde concentration, crosslinking time, enzyme immobilization time were determined as 5%, 10 h and 12 h, respectively. The immobilized laccase showed a better stability resistance to temperature and pH change. Comparison of storage stabilities showed that the immobilized laccase retained more than 62.6% of its initial activity when stored at 4°C for 20 days. However, the free laccase lost most of its activity under the same conditions. The immobilized laccase retained 64.5% of its initial activity after 10 repeated batches of reaction.

Degradation of chlortetracycline using immobilized laccase on Polyacrylonitrile-biochar composite nanofibrous membrane

“…Also, Jiang et al immobilized laccase onto chitosan microspheres and observed 70% of activity retention after one month storage at 4±1 °C, while free enzyme resulted in 30% of its initial activity [27]. and laccase and therefore lost only 30% of laccase activity after 7 cycles of ABTS oxidation [29]. Likewise, Xu et al immobilized laccase onto PAN nanofibers through amidination process and reported that the immobilized laccase lost 30 % of the initial activity after 7 cycles [25].…”

Covalent Immobilization of Laccase onto Nanofibrous Membrane for Degradation of Pharmaceutical Residues in Water

“…reported a slight improvement in thermal stability of immobilized laccase (20-45%)21,25 , Jiang et al observed higher sensitivity of laccase after immobilization onto chitosan compared to free laccase (up to 65 %)14 .…”

A Perspective Review on the Application of Polyacrylonitrile‐Based Supports for Laccase Immobilization

“…[42] Thus, it is possible to see the influence of the concentration of glutaraldehyde as a parameter for laccase immobilization. This was reported by Feng et al (2016) when they covalently immobilized the laccase on amidoxime polyacrylonitrile/montmorillonite (AOPAN/ MMT) nanofibrous membrane. The researchers noticed that the increase in the concentration of glutaraldehyde provided an increase in the amount of immobilized laccase until reaching a saturation point of 5 %, where the amount of laccase reached 89.12 mg/g, maximum retention of enzyme in the support.…”

“…The researchers noticed that the increase in the concentration of glutaraldehyde provided an increase in the amount of immobilized laccase until reaching a saturation point of 5 %, where the amount of laccase reached 89.12 mg/g, maximum retention of enzyme in the support. [43] Another method used is the activation of the PAN surface by amidination (Figure 2b), where the nitrile groups of polyacrylonitrile are activated in a medium containing ethanol/ HCl resulting in the production of imidoester, which in turn reacts with the amino groups present in the enzyme to form amidino bonds. [44] The laccase was immobilized on amidina-tion activated nanofiber PAN and successfully applied to remove 2,4,6-trichlorophenol (TCP) from the water.…”