Are all chitosans the same?
Not at all. There are many different chitosans. They are all composed of glucosamine and N-acetylglucosamine units, but in varying amounts and varying proportions. The total number of units is termed the degree of polymerization, the percentage of acetylated units is termed the degree of acetylation. In addition, the distribution of the two monomeric units within the linear chitosan chain may vary, i.e. chitosans may have different patterns of acetylation. This structural variability is also responsible for the functional variability of chitosans. As an example, the chitosans with the highest antimicrobial activities are not the same as those with the best immuno-stimulatory activities in plants. Inspite of their seemingly simple structure, chitosans, thus, have complex structure-function relationships which are still not fully understood. Hence, for each application, the best suited chitosan needs to be identified.