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‐Glu E @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‐Glu C @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 NaBH 4 .