16.4 Parameters Influencing Immobilization
When planning enzyme immobilization some parameters should be carefully considered. Especially physical properties of the selected carrier, i.e., the particle size,
shape, porosity, and surface area, are very important. The type of the carrier
consisting of organic or inorganic material with hydrophobic or hydrophilic properties and carrying surface charge and functionalization should be considered before
starting the immobilization procedure. Mechanical and chemical stability of the
carrier is important when selecting the type of reactors, reaction media, and reaction
conditions (Cao 2006; Hanefeld et al. 2009).
Catalytic properties are linked to the enzymes and involve the turnover rate,
selectivity, substrate specificity and stability at various pH values, extreme temperatures, and in different aqueous and organic media. Some other parameters, such as
the size of the enzyme, its isoeletric point, conformational flexibility, surface functional groups, surface charge, the presence of hydrophobic and hydrophilic domains,
should be taken into account when planning the immobilization. Catalytic functions
are usually designed to reach high productivity, long-term stability, and broad
applicability of the catalysts (Cao 2006; Hanefeld et al. 2009).
The third group of important parameters are specific factors related to the reaction
system. Composition and viscosity of the reaction medium, reaction thermodynamics, mass transfer limitation, enzyme inhibition or precipitation, non-specific solutesupport interactions represent only a few examples (Hanefeld et al. 2009).
Immobilization procedure should lead to the production of robust catalysts.
Proper selection of the carrier, enzyme, and reaction parameters is crucial to achieve
success. The resulting biocatalytic activity is influenced by the enzyme density on
the carrier, enzyme orientation and conformation (Ding et al. 2015).
Several analytical methods have been developed to control the immobilization
process and track the post-immobilization changes in the enzymes. These techniques
are commonly based on surface analysis and involve, e.g., scanning electron microscopy, surface plasmon resonance, circular dichroism, and Förster resonance energy
transfer (Mohamad et al. 2015). Time-of-flight secondary ion mass spectroscopy
(TOF-SIMS) represents one of the most powerful analytical tools that can provide
detailed surface characterization including the composition, structure, orientation,
and spatial distribution of the molecules on the surface (Kim et al. 2015). Conformational analysis of the immobilized enzymes is very important and helps to
develop and improve the enzyme immobilization strategies (Secundo 2013).
16.5 Basic Immobilization Techniques
Selection of the appropriate technique is crucial for effective immobilization of
enzymes. The most common techniques involve adsorption, covalent binding,
entrapment, encapsulation, and cross-linking. The prepared nanobiocatalysts are
348
M. Čvančarová et al.
When planning enzyme immobilization some parameters should be carefully considered. Especially physical properties of the selected carrier, i.e., the particle size,
shape, porosity, and surface area, are very important. The type of the carrier
consisting of organic or inorganic material with hydrophobic or hydrophilic properties and carrying surface charge and functionalization should be considered before
starting the immobilization procedure. Mechanical and chemical stability of the
carrier is important when selecting the type of reactors, reaction media, and reaction
conditions (Cao 2006; Hanefeld et al. 2009).
Catalytic properties are linked to the enzymes and involve the turnover rate,
selectivity, substrate specificity and stability at various pH values, extreme temperatures, and in different aqueous and organic media. Some other parameters, such as
the size of the enzyme, its isoeletric point, conformational flexibility, surface functional groups, surface charge, the presence of hydrophobic and hydrophilic domains,
should be taken into account when planning the immobilization. Catalytic functions
are usually designed to reach high productivity, long-term stability, and broad
applicability of the catalysts (Cao 2006; Hanefeld et al. 2009).
The third group of important parameters are specific factors related to the reaction
system. Composition and viscosity of the reaction medium, reaction thermodynamics, mass transfer limitation, enzyme inhibition or precipitation, non-specific solutesupport interactions represent only a few examples (Hanefeld et al. 2009).
Immobilization procedure should lead to the production of robust catalysts.
Proper selection of the carrier, enzyme, and reaction parameters is crucial to achieve
success. The resulting biocatalytic activity is influenced by the enzyme density on
the carrier, enzyme orientation and conformation (Ding et al. 2015).
Several analytical methods have been developed to control the immobilization
process and track the post-immobilization changes in the enzymes. These techniques
are commonly based on surface analysis and involve, e.g., scanning electron microscopy, surface plasmon resonance, circular dichroism, and Förster resonance energy
transfer (Mohamad et al. 2015). Time-of-flight secondary ion mass spectroscopy
(TOF-SIMS) represents one of the most powerful analytical tools that can provide
detailed surface characterization including the composition, structure, orientation,
and spatial distribution of the molecules on the surface (Kim et al. 2015). Conformational analysis of the immobilized enzymes is very important and helps to
develop and improve the enzyme immobilization strategies (Secundo 2013).
16.5 Basic Immobilization Techniques
Selection of the appropriate technique is crucial for effective immobilization of
enzymes. The most common techniques involve adsorption, covalent binding,
entrapment, encapsulation, and cross-linking. The prepared nanobiocatalysts are
348
M. Čvančarová et al.