In situ and post-synthesis immobilization of enzymes on nanocrystalline MOF platforms to yield active biocatalysts

BACKGROUNDVery recently, metal-organic framework (MOF) materials have been postulated as emerging supports to achieve solid-state enzyme-contained biocatalysts. In this work, post-synthesis and in situ strategies to immobilize -glucosidase and laccase on different MOF materials were studied. The MOF-based supports, i.e. MIL-53(Al), NH2-MIL-53(Al) and Mg-MOF-74, were prepared under soft and sustainable conditions (room temperature and pH values compatible with enzymatic activity), allowing development of the in situ strategy. RESULTSIn both post-synthesis and in situ approaches, the intercrystalline mesoporosity of the MOF-based support favored the immobilization efficiency or the specific activity. The latter expressed as units per milligram of immobilized enzyme was higher in the post-synthesis immobilization, whereas the biocatalysts prepared in situ gave much higher enzyme loading (over 85%) and lower enzyme leaching (around 5%). The in situ approach even worked in a non-aqueous (N,N-dimethylformamide) media in which the free enzyme was completely inactive. The immobilized enzymes are much larger than the structural pores of the MOFs. CONCLUSIONSEnzymes can be efficiently immobilized on nanocrystalline MOFs prepared under soft and sustainable conditions despite the supports lacking large enough pores to host the enzymes. The in situ approach is very efficient capturing enzymes and preserving some of their activity even under adverse conditions. (c) 2017 Society of Chemical Industry