What are chitosan oligomers?
Chitosan oligomers are short chain chitosans, consisting a various numbers, various ratios, and varying sequences of N-acetylglucosamine and glucosamine monomeric units. There is no clear distinction between chitosan oligomers and chitosan polymers. Typically, chitosan oligomers are defined as short chains of up to 10-20 monomeric units, with at least one glucosamine unit present (otherwise, they would be chitin oligomers). Their names reflect their degrees of polymerization (DP): DP 2 = dimer, DP 3 = trimer, DP 4 = tetramer, DP 5 = pentamer, DP 6 = hexamer, DP 7 = heptamer, DP 8 = octamer, DP 9 = nonamer, DP 10 = decamer, DP 11 = undecamer, Dp 12 = dodecamer, etc.). Chitosan oligomers are easily soluble in water. Chitosan oligomers produced in situ through the action of chitinases or chitosanases present in a target tissue are thought to be responsible for many of the biological activities of chitosan polymers, such as the immuno-stimulatory activities in plants and animals/humans. Chitosan oligomers are sometimes also called chito-oligosaccharides and abbreviated as COS, but the term is ambiguous and not clearly defined, often including both chitin and chitosan oligomers. To distinguish them from fully acetylated chitin oligomers, partially acetylated chitosan oligomers can be abbreviated as paCOS.