Lm. Dai et al., Biomedical coatings by the covalent immobilization of polysaccharides ontogas-plasma-activated polymer surfaces, SURF INT AN, 29(1), 2000, pp. 46-55
As the surface properties of polymeric biomaterials play an important role
in the performance: of biomedical devices, highly hydrophilic, ultrathin co
atings were applied onto hydrophobic, perfluorinated and organosilicon poly
mers by the covalent immobilization of polysaccharides using a reductive am
ination reaction, Gas plasma (r.f. glow discharge) methods were employed to
equip the surfaces of these normally unreactive polymeric substrates with
chemical groups capable of reacting with polysaccharides in aqueous solutio
n, in one variant, ammonia plasmas were used to introduce into the polymer
surfaces a submonolayer of amine groups, Alternatively, an n-heptylamine pr
ocess vapour was used to deposit a thin plasma polymer him that possessed s
urface amine groups, The polysaccharides were activated for covalent immobi
lization by periodate oxidation, which produced hemiacetal structures, as r
evealed by NMR and XPS. The hemiacetal structures in the polysaccharide cha
ins were reacted with the surface amine groups on the polymers. The resulti
ng Schiff base linkages were stabilizers by reduction to secondary amine li
nkages using sodium cyanoborohydride, Detailed surface analysis is importan
t for verification that the intended chemistries have indeed been achieved
in such multilayer coating schemes, X-ray photoelectron spectroscopy provid
ed a thickness estimate of 1 +/- 0.3 nm for the polysaccharide coatings in
the dehydrated state, Copyright (C) 2000 John Wiley & Sons, Ltd.