Alpha-Glucosidase Enzyme Immobilized Dextran-Co Metal Nanoparticle Cryogel Composite Systems as Dual Catalyst with Enhanced Stability and Catalytic Activity

Abstract

Here, dextran (Dex) cryogels were prepared and used for the immobilization of α-Glu enzyme via two different techniques of entrapment and covalent linking. The entrapment of α-Glu enzyme within Dex cryogels (α-GluE@Dex) during the synthesis process caused almost 70 % activity loss. On the other hand, the Dex cryogels with α-Glu enzyme immobilized via covalent linking (α-GluC@Dex) maintained 91±1.1 % activity and afforded 10 consecutive usages and could be stored at 25 °C for 10 days with more than 50 % activity. Moreover, we prepared Cobalt (Co) metal nanoparticle containing Dex-Co cryogel composite to be used to immobilize the α-Glu enzyme via covalent linking to attain an α-GluC@Dex-Co catalyst system with dual catalytic performance e. g., enzymatic and chemical reduction of the substrate and its’ by-product for the first time. The prepared α-GluC@Dex-Co cryogels system was used for enzymatic hydrolysis of 4-nitrophenyl-α-D-glucopyranoside to glucose and 4-nitrophenol, and then the reduction of 4-nitrophenol to 4-aminophenol catalyzed by the Co metal nanoparticles present as co-catalyst within the cryogel network. The enzymatic activity of α-GluC@Dex-Co cryogels was calculated as 72±3.1 % and the cryogel reduced the enzymatic reaction by-product of 4-nitrophenol to 4-aminophenol in 7 min in the presence of NaBH4.