posted on 2021-01-13, 20:35authored byWeibin Liang, Peter Wied, Francesco Carraro, Christopher J. Sumby, Bernd Nidetzky, Chia-Kuang Tsung, Paolo Falcaro, Christian J. Doonan
Because of their efficiency, selectivity,
and environmental sustainability,
there are significant opportunities for enzymes in chemical synthesis
and biotechnology. However, as the three-dimensional active structure
of enzymes is predominantly maintained by weaker noncovalent interactions,
thermal, pH, and chemical stressors can modify or eliminate activity.
Metal–organic frameworks (MOFs), which are extended porous
network materials assembled by a bottom-up building block approach
from metal-based nodes and organic linkers, can be used to afford
protection to enzymes. The self-assembled structures of MOFs can be
used to encase an enzyme in a process called encapsulation when the
MOF is synthesized in the presence of the biomolecule. Alternatively,
enzymes can be infiltrated into mesoporous MOF structures or surface
bound via covalent or noncovalent processes. Integration of MOF materials
and enzymes in this way affords protection and allows the enzyme to
maintain activity in challenge conditions (e.g., denaturing agents,
elevated temperature, non-native pH, and organic solvents). In addition
to forming simple enzyme/MOF biocomposites, other materials can be
introduced to the composites to improve recovery or facilitate advanced
applications in sensing and fuel cell technology. This review canvasses
enzyme protection via encapsulation, pore infiltration, and surface
adsorption and summarizes strategies to form multicomponent composites.
Also, given that enzyme/MOF biocomposites straddle materials chemistry
and enzymology, this review provides an assessment of the characterization
methodologies used for MOF-immobilized enzymes and identifies some
key parameters to facilitate development of the field.