Blood interface biomaterials - Biomaterials and Devices for the Circulatory System - page 37

Polymeric biomaterial

Hydrogel or
hydrogel-
forming
monomer

Surface coating Polymer blending IPN formation

Surface
crosslinking

Melting

Hydrogel-modified polymeric surface

2.2 Molecular design of hydrogel-modifi ed surface.

during their insertion into the vessels of the patient (Nurdin et al. , 1996).
Glutaraldehyde-crosslinked PVA hydrogel with and without heparin
(Sefton et al. , 1987) were reported to modify the surface of a substrate to
achieve improved blood compatibility.
Polysaccharides are very promising modifi ers of biomaterials because of
their abundant availability, structural diversity, high hydrophilicity, plausible
degradability and likely biocompatibility (Zdrahala, 1996). By coating poly-
saccharides, such as dextran (Österberg et al. , 1995) and a dextran-contain-
ing copolymer (Marchant et al. , 1998), the modifi ed surfaces show resistance
to protein deposition. Cyclodextrins have been used to modify polymeric
biomaterials for improved blood compatibility (Zhao & Courtney, 2007,
2009).
In addition to the hydrogel coating approach, the surfaces modifi ed
with hydrogel can be achieved by polymer blending and interpenetrating
network (IPN) formation. Lee et al. (1995) modifi ed a poly(ethylene tere-
phthalate) (PET) textile vascular graft using a semi-IPN formation tech-
nique to achieve an alginate-modifi ed surface. Gutowsky & Kim (1997)
reported an IPN coating technique using a thermosensitive hydrogel for
controlled delivery of heparin. According to this report, a hydrophobic
surface was immersed into the monomer/solvent system initially. After
polymerisation, a portion of the hydrogel was formed within the hydro-
phobic surface to obtain an IPN. The remainder of the hydrogel, which
polymerises above the interface, forms a new hydrogel surface. Inoue et al.
(1997) modifi ed polyurethane catheters by utilisation of IPN formation

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