Cyclodextrin glucosyltransferase immobilization on polydopamine-coated Fe3O4 nanoparticles in the presence of polyethyleneimine for efficient β-cyclodextrin production

An enzymatic approach to β-cyclodextrin synthesis attracts the attention of food engineers and chemists because of the broad applications of β-cyclodextrin in the food industry and the demand for a green process for β-cyclodextrin production. Achieving a high recovery of cyclodextrin glycosyltransferase through immobilization and a high proportion of β-cyclodextrin in a product mixture of cyclodextrins would improve the purification process of β-cyclodextrin. In this study, a recombinant cyclodextrin glycosyltransferase (CGTase) was immobilized on polydopamine-Fe 3 O 4 (PDA-Fe 3 O 4 ) nanoparticles in the presence of polyethyleneimine (PEI). After optimization of the preparation of the PDA-Fe 3 O 4 nanoparticles and the CGTase immobilization step, 77.9% of the CGTase was recovered. The immobilized CGTase exhibited good thermal and operational stabilities, and gave a ratio of 88.9% β-cyclodextrin when the reaction temperature and kinetic parameters were optimized. Immobilized CGTase was recycled nine times and retained 19.1% β-activity and 0% γ-activity. This study has established a reliable approach to the high recovery of CGTase during efficient β-cyclodextrin production.