Fig.3

3.3 Recovery rate of immobilized enzyme

MOF ZIF-8 was selected for enzyme immobilization for its low cost and biocompatibility. DAADH were encapsulated into the ZIF-8 framework by a biomimetic mineralization. Enzyme immobilization by ZIF-8 and hybrid material of ZIF-8 with graphene (ZIF-8/RGO) were investigated. The loading rate of enzyme to both carriers are above 99%. Compared with free DAADH, the activity DAADH/ZIF-8 was only 60.0% while the activity of DAADH/ZIF-8/RGO was enhanced by 165.6% (Fig.4).
The results indicated that the addition of RGO can form hybrid material with higher biocompatibility, probably due to hydrophobic interaction between RGO and DAADH [24], which can increase the stability of DAADH/ZIF-8/RGO. ZIF-8/RGO is a good carrier because MOF ZIF-8 encapsulate DAADH to restrict the movements related to unfold [25] and RGO increase enzyme stability.