Page 83 - Advances in Textile Biotechnology

62 Advances in textile biotechnology

range of materials such as metals and plastics. Pronase and alpha-chymo-
trypsin were successfully immobilized with this approach and thermostabil-

ity was even enhanced. When attached to filters, antifouling properties were
imparted. Since conventional antifouling paints contain toxic agents, such
bioactive coatings offer great opportunities for food-processing equipment,

ship hulls, medical implants, ultrafiltration membranes, and many other
devices.
Plasma treatment has been used for activation of polyethylene (Alvarez
et al., 2003) whereas PET and PA were activated photochemically before
cross-linking with diallylphthalate or cyclohexane-1,4-dimethanol divinyl
ether (Opwis et al., 2005). Polypropylene-based ion-exchange textiles
were constructed by UV-induced graft polymerization for immobilization
of urease coupled with N-(3-dimethylaminopropyl)-N′-ethylcarbodiimide
hydrochloride, N-cyclohexyl-N′-[β-(N-methylmorpholino)ethyl]carbodi-
imide p-toluenesulfonate or glutaraldehyde (Yeon and Lueptow, 2006).
Another strategy involves activation of polypropylene membranes with
polyaniline using ammonium persulfate as the oxidizer. This pretreatment
greatly facilitated both adsorptive and covalent immobilization of proteins
such as HRP (Piletsky et al., 2003). Limited enzymatic hydrolysis of poly-
amide by protease has been used to insert anchor groups for covalent
immobilization of laccase using glutaraldehyde together with 1,6-hexanedi-
amine as a spacer (Fig. 3.1) (Silva et al., 2007). In general, enzymatic surface
modifi cation is a new strategy to activate the surface of synthetic polymers
including polyamide (Heumann et al., 2009), polyalkyleneterephthalates
(Brückner et al., 2008, Eberl et al., 2008) and polyacrylonitriles (Fischer-
Colbrie et al., 2007).

Highly specific interaction of the glycoproteins avidin or streptavidin to
biotin can be exploited for enzyme immobilization on surfaces. Biotin binds
−1
15
almost irreversibly to streptavidin with a K a = 1 × 10 M , which is similar
to that of covalent bonds (Wilchek et al., 1988). Use of this interaction
involves multiple attachment of biotin to the target proteins (i.e. enzymes)
which consequently can bind several molecules of avidin (Fig. 3.2). These
interactions are exploited in bioanalytics or affinity chromatography involv-

ing labeled or immobilized avidin, respectively. Alternatively, avidin is
bound to biotinylated surfaces followed by immobilization of biotinylated
enzymes (Janolino and Swaisgood, 2002). Usually this process can be carried
out under mild conditions, which are benefi cial for preservation of enzyme
activity. Using this approach, urease was immobilized on cellulose fabrics
(Magne et al., 2002).
Similarly, trypsin was immobilized on cellulose beads biotinylated with
sulfosuccinimidyl-6-(biotinamido) hexanoate (NHS-LC-biotin) resulting in
−1
a biotin content of 1.15 μmol g (Janolino and Swaisgood, 2002).

Specific binding modules of polymer-modifying enzymes also offer a
potential for enzyme immobilization. Many (hemi)cellulolytic enzymes

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