Chitin is the most abundant aminopolysaccharide
polymer occurring in nature, and is the building material that gives strength
to the exoskeletons of crustaceans, insects, and the cell walls of fungi.
Through enzymatic or chemical deacetylation, chitin can be converted to its
most well-known derivative, chitosan. The main natural sources of chitin are
shrimp and crab shells, which are an abundant byproduct of the food-processing
industry, that provides large quantities of this biopolymer to be used in biomedical
applications. In living chitin-synthesizing organisms, the synthesis and
degradation of chitin require strict enzymatic control to maintain homeostasis.
Chitin synthase, the pivotal enzyme in the chitin synthesis pathway, uses
UDP-N-acetylglucosamine (UDPGlcNAc), produce the chitin polymer, whereas,
chitinase enzymes degrade chitin. Bacteria are considered as the major
mediators of chitin degradation in nature. Chitin and chitosan, owing to their
unique biochemical properties such as biocompatibility, biodegradability,
non-toxicity, ability to form films, etc, have found many promising biomedical
applications. Nanotechnology has also increasingly applied chitin and
chitosan-based materials in its most recent achievements. Chitin and chitosan
have been widely employed to fabricate polymer scaffolds. Moreover, the use of
chitosan to produce designed-nanocarriers and to enable microencapsulation
techniques is under increasing investigation for the delivery of drugs,
biologics and vaccines. Each application is likely to require uniquely designed
chitosan-based nano/micro-particles with specific dimensions and cargo-release
characteristics. The ability to reproducibly manufacture chitosan
nano/microparticles that can encapsulate protein cargos with high loading
efficiencies remains a challenge. Chitosan can be successfully used in
solution, as hydrogels and/or nano/microparticles, and (with different degrees
of deacetylation) an endless array of derivatives with customized biochemical
properties can be prepared. As a result, chitosan is one of the most
well-studied biomaterials. The purpose of this review is to survey the
biosynthesis and isolation, and summarize nanotechnology applications of chitin
and chitosan ranging from tissue engineering, wound dressings, antimicrobial
agents, antiaging cosmetics, and vaccine adjuvants. - See more at:
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