Chemistry Reference
In-Depth Information
Table 4.2
Summary and schematic illustration of enzyme immobilisation techniques
Approach
Illustration
Description
Covalent Binding
Enzymes immobil-
ised onto support
through covalent
bonds
Adsorption:
Ionic Binding
Enzyme ionically
bonded onto sup-
port through elec-
trostatic interactions
(dotted line)
Physical Adsorption
Enzyme physically
adsorbed onto sup-
port through inter-
actions such as van
der Waals forces,
hydrogen bonding
and hydrophobic
interactions
Cross-Linking/
Aggregation
Additional reagents
cause inter-molecu-
lar cross-linking. If
significant enough,
enzymes become
insoluble
Entrapment/
Encapsulation
Enzyme becomes
entrapped in a
surrounding lattice/
matrix structure or
becomes 'encapsu-
lated' in small cap-
sule like structures
necessary [
2
]. In industry, pre-manufactured resin supports are commonly encoun-
tered due to their effectiveness, but their cost is a major hindrance. Manufactured
ranges include Sepabeads, Amberlite, Lewatit and Eupergit [
13
]. They largely come
in bead form due to their large surface area. Furthermore, a range of inorganic sup-
ports are commonly utilised and these include nanoparticles, gels and beads pre-
pared from ceramics (silica, titania, calcium-compounds) and metals [
14
,
15
].
