Laccase Immobilization onto Magnetic β-Cyclodextrin-Modified Chitosan: Improved Enzyme Stability and Efficient Performance for Phenolic Compounds Elimination

Three types of improved Fe3O4 magnetic nanoparticles (MNPs), including poly(amidoisophthalicacid) coated magnetite nanoparticles (Fe@PA), cyclodextrin (CD) anchored Fe@PA (Fe@PA-CD), and chitosan (Cs) coated Fe@PA-CD (Fe@PACD-Cs) were successfully developed and characterized. Laccase immobilization onto MNPs was carried out via physical adsorption. The maximal and minimal loading capacity were obtained for Fe@PA and Fe@PA-CD-Cs, respectively. Fe@PA-CDCs-laccase exhibited around 100% of the maximum activity at pH 4 and maintained 70% of its initial activity within the temperature range of 15-55 degrees C; and Cs coated nanoparticles were more efficient than non-coated. Fe@PA-CD-Cs-laccase maintained 70% of its initial activity up to 12 d from the first day of storage at 25 degrees C whereas the free laccase, Fe@PA-laccase, and Fe@PA-CD-laccase kept 10%, 28%, and 33% of initial activity, respectively. Furthermore, bio-removal of phenolic compounds was performed by the free and immobilized enzyme. Fe@PA-CD-Cs-laccase showed maximal removal with 96.4% and 85.5% for phenol and bisphenol A, respectively. It seems that Fe@PA-CD-Cs could be an appropriate support for immobilization of other enzymes in various industrial application especially bioremoval of phenolic compounds.