Hydrolytic enzymes break the glycosidic bonds in chitosan and provide an advanced tool to selectively cut desired structures from heterogeneous polymeric structures.<\/p>\n\n\n\n
Recently developed \u2018fingerprinting\u2019 analysis based on enzymatic\u2013mass spectrometric techniques opens windows for the analysis of not only chitosan oligomers but also polymers.<\/p>\n\n\n\n
In studies of the siRNA delivery system, it has been found that not only the degree of deacetylation but also the acetylation pattern are among the governing parameters in gene delivery efficiency.<\/p>\n\n\n\n
The structural homogeneity of chitosan oligosaccharides is the key factor affecting their inflammatory activity, ability to condense siRNA, and antitumor activity.<\/p>\n\n\n\n
Chitosan, an amino polysaccharide mostly derived from crustaceans, has been recently highlighted for its biological activities that depend on its molecular weight (MW), degree of deacetylation (DD), and acetylation pattern (AP). More importantly, for some advanced biomaterials, the homogeneity of the chitosan structure is an important factor in determining its biological activity. Here we review emerging enzymes and cell factories, respectively, for\u00a0in vitro<\/em>\u00a0and\u00a0in vivo<\/em>\u00a0preparation of chitosan oligosaccharides (COSs), focusing on advances in the analysis of the AP and structural modification of chitosan to tune its functions. By \u2018mapping\u2019 current knowledge on chitosan\u2019s\u00a0in vitro<\/em>\u00a0and\u00a0in vivo<\/em>\u00a0activity with its MW and AP, this work could pave the way for future studies in the field.<\/p>\n\n\n\n