Polysaccharide Derivatives for the Modification of Surfaces by Self-Assembly

Typical reaction pathways for the synthesis of self-assembling polysaccharides (dextran, cellulose, and xylan) are discussed. Dextran- and cellulose derivatives with different sulfur-containing functional groups (thiol-, thioester- and thioether moieties) possess a remarkable ability to self-assemble on gold surfaces. Aminocellulose derivatives, obtained by nucleophilic substitution of cellulose-p-toluenesulfonic acid ester with di- and oligoamines, are able to form monolayers on various substrates. The NH 2 moieties of these biocompatible aminocellulose surfaces can be used to immobilize enzymes while maintaining enzyme activity. A novel approach to aminocellulose through introduction of polyamidoamine-based dendrons by the copper-catalyzed Huisgen reaction of azido cellulose with dendrons possessing ethynyl moieties is described. Furthermore, the preparation of cationic xylan derivatives and their adsorption behavior on cellulose and two types of self-assembled monolayers is reviewed. Xylan layers on various pulp fibers were found to enhance paper strength.