Covalent immobilization of amyloglucosidase on magnetic-silver nanoparticles for rapid and reusable saccharification of cassava peel.

Efficient conversion of agricultural waste into fermentable sugars is central to sustainable second-generation biofuel technologies. This study reports the covalent immobilization of amyloglucosidase onto a magnetic silver nanoparticle (Ag-MNP) hybrid support for the saccharification of cassava peel. The Ag-MNP hybrid support was employed to combine magnetic recovery with a favourable immobilization microenvironment for enhanced catalytic performance during cassava peel saccharification. X-ray diffraction identified a multi-phase iron oxide system comprising maghemite, hematite, and goethite, with a mesoporous architecture of 18-20 nm pore diameter. Covalent enzyme attachment via glutaraldehyde-mediated imine bond formation was confirmed by infrared spectroscopy. The immobilized biocatalyst achieved 92.32% total reducing sugar recovery within 50 min, surpassing the free enzyme performance of 86.87% under identical conditions. Kinetic analysis revealed an elevated maximum reaction rate of 6.4 μmol min-1, compared with 5.0 μmol min-1 for the free enzyme, attributed to favourable active-site orientation and the physicochemical properties of the Ag-MNP hybrid support. Chromatographic analysis confirmed glucose as the dominant hydrolysate product at 90.26%. The biocatalyst retained 54% of its initial activity after seven operational cycles at pH 5.0 and 65 °C. No inhibitory byproducts were detected under the conditions tested, supporting its potential as a reusable biocatalyst for generating fermentable sugars for bioethanol production.