Use of supramolecular chemistry based on β-cyclodextrin-grafted chitosan beads to prepare green biocatalytic materials†

The use of biomass-derived materials as supports for enzyme immobilization is of interest for developing biocatalytical processes based on renewable resources. Reversible immobilization offers a solution to the problem of enzyme activity loss over time, as it allows for the removal of deactivated enzymes and their replacement with fresh ones using a renewable biopolymer. In this work, β-cyclodextrin-grafted chitosan (Ch-CD) has been prepared and used as support to reversibly immobilized adamantane-modified enzymes via supramolecular host–guest interactions in an environmentally friendly aqueous medium. The prepared Ch-CD beads were characterized by solid-state ¹³C and ¹⁵N CP/MAS (cross-polarization/magic angle spinning) NMR spectroscopy. The performance of three types of enzymes immobilized by this method has been studied: β-galactosidases in the hydrolysis of β-galactopyranosides, one glucose oxidase in the oxidation of glucose, and one peroxidase in the oxidation of 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid). A double sequential enzyme reaction catalyzed by immobilized glucose oxidase/peroxidase was performed, showing the possibility to develop a glucose test by means of this sustainable biocatalysis. The reusability of the biocatalytic materials was dependent on the type, source of enzyme and the linker used in the preparation. The enzymes bound to cyclodextrin-grafted chitosan beads were desorbed after washing with a β-CD solution, thus being able to recycle the Ch-CD beads for a new enzyme immobilization.