The effects of NaCl on enzyme encapsulation by zeolitic imidazolate frameworks-8

Metal-organic framework (MOF) has generated a lot of research interests for it can be employed as immobilization material for enzyme. There are many small molecules in enzyme solution during the extraction process, such as NaCl. It is important to study the effects of the small molecules on MOFs. Here we report a facile and efficient method to encapsulate (R)-1-phenylethanol dehydrogenase ((R)-PEDH) into zeolitic imidazolate framework-8 (ZIF-8). In this work, the effects of NaCl on shape of ZIF-8 and enzyme encapsulation have been investigated. The scanning electron microscope (SEM) results showed that 0.1 M NaCl affect the morphology of ZIF-8 while the crystal structure was not changed analyzed by X-ray diffraction (XRD), and 0.1 M NaCl consisted in the encapsulation system of (R)-PEDH@ZIF-8 enhanced the activity up to 2.5 folds than no NaCl consisted during prepared (R)-PEDH@ZIF-8. The (R)-PEDH@ZIF-8 (prepared with 0.1 M NaCl) enhanced the storage stability and resist ability against trypsin, and the (R)-PEDH@ZIF-8 has been successfully reused.