Laccase Immobilisation on Poly(ethylene) Terephthalate Grafted with Maleic Anhydride (PET-g-MAH) Nanofiber Mat

Abstract

A comparative study was carried out on three different enzyme immobilisation methods which were physical adsorptions (PA), covalent bonding (CV) and covalent bonding of cross-linked enzyme aggregates (CL) for laccase immobilisation on Poly(ethylene) Terephthalate (PET) grafted with Maleic Anhydride (MAH) nanofiber mats. The chemically inert PET was successfully grafted with MAH at temperature between 40 - 45 C and used as the carrier to immobilised laccase in the form of electrospun nanofiber mats. The peaks from carbonyl (C=O) and alkene (C=C) groups appeared on the spectral subtraction between PET and PET-g-MAH nanofiber mats. These groups might be the potential group to form covalent bond between the amine groups of laccase enzyme. Laccase immobilised on the PET-g-MAH nanofiber mats using CL methods using glutaraldehyde as crosslinker gave the best performance with the highest enzyme loading and immobilisation yield which were 40.88 µg/mg and 48.37 %. On top of that, the immobilised laccase on PET-g-MAH nanofiber mats also managed to retain 69.01 % of its initial activity after 10 repeated cycles of 2, 2-azino-bis 3-ethylbenzothiazoline-6-sulfonic acid (ABTS) oxidations. These results demonstrate that PET-g-MAH nanofiber is a good material to be considered as laccase carrier.