Table 1

3.9 Morphology analysis

The morphology of the immobilized-DAADH was studied. SEM image indicated a mesoporous structure with pore sizes of different scales (Fig.9). This mesoporous structure probably facilitates the substrate’s diffusion. ZIF-8 provides a biocompatible carrier for DAADH immobilization. The interaction of ZIF-8 and the peptide linker improved the stability of the immobilized enzyme. With the addition of RGO, the immobilized enzyme DAADH/ZIF-8/RGO showed amorphological layers.
The addition of RGO can form hybrid material (ZIF-8/RGO) with higher biocompatibility, which may due to hydrophobic interaction between RGO and DAADH [24]. ZIF-8/RGO composites can effectively protect the active conformation of enzymes and improve the stability of enzymes in extreme conditions such as high temperature and high pH value. The DAADH/ZIF-8/RGO is expected to be further applied in biocatalysis [29].