[[Polysaccharide|Polysaccharides]] have been used as [[thin film|thin film]] coatings for biomaterial surfaces. Polysaccharides are extremely hydrophilic and will have small [[Contact angle|contact angles]]. They can be used for a wide range of applications due to their wide range of compositions. They can be used to reduce the [[adsorption|adsorption]] of proteins to biomaterial surfaces. Additionally, they can be used as receptor sites, targeting specific biomolecules. This can be used to activate specific biological responses.
Covalent attachment to a substrate is necessary to immobilize polysaccharides, otherwise they will rapidly desorb in a biological environment. This can be a challenge due to the fact that the majority of biomaterials do not possespossess the surface properties to covalently attach polysaccharides. This can be achieved by the introduction of [[amine|amine groups]] by RF glow discharge plasma. Gases used to form amine groups, including ammonia or n-heptylamine vapor, can be used to deposit a thin film coating containing surface amines. Polysaccharides must also be activated by oxidation of anhydroglucopyranoside subunits. This can be completed with sodium metaperiodate (NaIO<sub>4</sub>). This reaction converts anhydroglucopyranoside subunits to cyclic hemiacetal structures, which can be reacted with amine groups to form a Schiff base linkage (a carbon-nitrogen double bond). These linkages are unstable and will easily [[dissociation (chemistry)|dissociate]]. Sodium cyanoborohydride (NaBH<sub>3</sub>CN) can be used as a stabilizer by reducing the linkages back to an amine.<ref name=immobilization>{{cite journal |doi=10.1002/(SICI)1096-9918(200001)29:1<46::AID-SIA692>3.0.CO;2-6 |title=Biomedical coatings by the covalent immobilization of polysaccharides onto gas-plasma-activated polymer surfaces |year=2000 |last1=Dai |first1=Liming |last2=Stjohn |first2=Heather A. W. |last3=Bi |first3=Jingjing |last4=Zientek |first4=Paul |last5=Chatelier |first5=Ronald C. |last6=Griesser |first6=Hans J. |journal=Surface and Interface Analysis |volume=29 |pages=46–55}}</ref>
