LAUSR

Abstract In the present work, the preparation of magnetic maghemite nanoparticles (MNPs), functionalized with amino-organosilanes and chitosan was investigated for a successful immobilization of enzyme β-galactosidase from Aspergillus oryzae. MNPs were synthesized by co-precipitation of Fe2+ and Fe3+ ions in the presence of ammonium. Immobilization techniques on both carriers were optimized by differing concentration of cross-linking reagent glutaraldehyde (GA) and pentaethylenehexamine (PEHA), where their influence on immobilization efficiency and residual activity of β-galactosidase was studied. Compared to the free enzyme, hyper-activation of enzyme was achieved in both immobilization methods. When functionalizing with amino-organosilanes, residual activity of 154%, 138% and 125% was achieved, using PEHA (20% (v/v)), GA (2.5% (v/v)) and combination of PEHA and GA (30% and 2% (v/v)), respectively. When functionalizing with chitosan, 129% of residual activity was achieved, with combination of PEHA and GA (30% and 0.5% (v/v)), respectively. Such immobilized β-galactosidase opens up a wide range of possibilities for implementation in various cleaner technologies, mostly benefiting in diary industries.