Editing Chitin

{{Short description|Long-chain polymer of a N-acetylglucosamine}}
{{Other uses}}
{{distinguish|chiton|keratin}}
[[Image:Chitin.svg|thumb|250px|right|Structure of the chitin molecule, showing two of the [[N-Acetylglucosamine|''N''-acetylglucosamine]] units that repeat to form long chains in β-(1→4)-linkage.]]
[[Image:Haworth projection of chitin.svg|thumb|250px|right|[[Haworth projection]] of the chitin molecule.]]
[[File:Glanzkaefer.jpg|thumb|A close-up of the wing of a [[leafhopper]]; the wing is composed of chitin.]]
[[Image:Lyristes plebejus.jpg|thumb|right|A [[cicada]] emerges from its nymphal exoskeleton; the shed exoskeleton is mostly modified chitin ([[sclerotin]]) but the wings and much of the adult body are still unsclerotized chitin at this stage]]

'''Chitin''' ([[carbon|C]]<sub>8</sub>[[hydrogen|H]]<sub>13</sub>[[oxygen|O]]<sub>5</sub>[[nitrogen|N]])<sub>n</sub> ({{IPAc-en|ˈ|k|aɪ|t|ᵻ|n}} {{respell|KY|tin}}) is a long-chain [[polymer]] of [[N-Acetylglucosamine|''N''-acetylglucosamine]], an [[amide]] derivative of [[glucose]]. Chitin is the second most abundant [[polysaccharide]] in nature (behind only [[cellulose]]); an estimated 1 billion tons of chitin are produced each year in the [[biosphere]].<ref>{{Cite book |last=Nelson, D.L., Cox, M.M. |title=Lehninger Principles of Biochemistry |publisher=McMillan Learning |year=2017 |isbn=978-1-4641-2611-6 |edition=7th}}</ref> It is a primary component of [[cell wall]]s in [[fungi]] (especially filamentous and mushroom-forming fungi), the [[exoskeleton]]s of [[arthropod]]s such as crustaceans and insects, the [[radula]]e, [[cephalopod beak]]s and [[Gladius (cephalopod)|gladii]] of [[mollusc]]s and in some nematodes and diatoms.<ref name=":0">{{Cite journal |last1=Sanjanwala |first1=Dhruv |last2=Londhe |first2=Vaishali |last3=Trivedi |first3=Rashmi |last4=Bonde |first4=Smita |last5=Sawarkar |first5=Sujata |last6=Kale |first6=Vinita |last7=Patravale |first7=Vandana |date=2022-12-02 |title=Polysaccharide-based hydrogels for drug delivery and wound management: a review |url=https://www.tandfonline.com/doi/full/10.1080/17425247.2022.2152791 |journal=Expert Opinion on Drug Delivery |language=en |volume=19 |issue=12 |pages=1664–1695 |doi=10.1080/17425247.2022.2152791 |pmid=36440488 |s2cid=254041961 |issn=1742-5247}}</ref><ref name=":1">{{Cite journal |last1=Sanjanwala |first1=Dhruv |last2=Londhe |first2=Vaishali |last3=Trivedi |first3=Rashmi |last4=Bonde |first4=Smita |last5=Sawarkar |first5=Sujata |last6=Kale |first6=Vinita |last7=Patravale |first7=Vandana |date=2024-01-01 |title=Polysaccharide-based hydrogels for medical devices, implants and tissue engineering: A review |url=https://www.sciencedirect.com/science/article/pii/S0141813023053874 |journal=International Journal of Biological Macromolecules |volume=256 |issue=Pt 2 |pages=128488 |doi=10.1016/j.ijbiomac.2023.128488 |pmid=38043653 |issn=0141-8130}}</ref>
It is also synthesised by at least some fish and [[lissamphibia]]ns.<ref>{{cite journal | pmid = 25772447 | doi=10.1016/j.cub.2015.01.058 | volume=25 | issue=7 | title=Chitin is endogenously produced in vertebrates | pmc=4382437 | journal=Curr Biol | pages=897–900 | last1 = Tang | first1 = WJ | last2 = Fernandez | first2 = JG | last3 = Sohn | first3 = JJ | last4 = Amemiya | first4 = CT | year=2015| bibcode=2015CBio...25..897T }}</ref> Commercially, chitin is extracted from the shells of crabs, shrimps, shellfish and lobsters, which are major by-products of the seafood industry.<ref name=":0" /><ref name=":1" /> The structure of chitin is comparable to cellulose, forming crystalline nanofibrils or whiskers. It is functionally comparable to the protein [[keratin]]. Chitin has proved useful for several medicinal, industrial and biotechnological purposes.<ref name=":1" /><ref>{{Cite journal |last1=Morin-Crini |first1=Nadia |last2=Lichtfouse |first2=Eric |last3=Torri |first3=Giangiacomo |last4=Crini |first4=Grégorio |date=2019-12-01 |title=Applications of chitosan in food, pharmaceuticals, medicine, cosmetics, agriculture, textiles, pulp and paper, biotechnology, and environmental chemistry |url=https://doi.org/10.1007/s10311-019-00904-x |journal=Environmental Chemistry Letters |language=en |volume=17 |issue=4 |pages=1667–1692 |doi=10.1007/s10311-019-00904-x |bibcode=2019EnvCL..17.1667M |issn=1610-3661}}</ref>

==Etymology==
The English word "chitin" comes from the [[French language|French]] word ''chitine'', which was derived in 1821 from the [[Greek language|Greek]] word χιτών (''khitōn'') meaning covering.<ref>{{cite journal| first= Auguste |last= Odier |publisher= presented: 1821| year= 1823| title= Mémoire sur la composition chimique des parties cornées des insectes| trans-title= Memoir on the chemical composition of the horny parts of insects| journal= Mémoires de la Société d'Histoire Naturelle de Paris| volume= 1| language= fr| pages= 29–42| url= https://books.google.com/books?id=JhhLAAAAYAAJ&pg=PA35 |quote= la Chitine (c'est ainsi que je nomme cette substance de chiton, χιτον, enveloppe…  [chitine (it is thus that I name this substance from chiton, χιτον, covering)]"}}</ref>

A similar word, "[[Chiton#Name|chiton]]", refers to a marine animal with a protective shell.

== Chemistry, physical properties and biological function ==

[[File:Chitin glucose and cellulose.svg|200px|thumb|right|Chemical configurations of the different monosaccharides (glucose and N-acetylglucosamine) and polysaccharides (chitin and cellulose) presented in [[Haworth projection]]]]

The structure of chitin was determined by [[Albert Hofmann]] in 1929. Hofmann hydrolyzed chitin using a crude preparation of the enzyme chitinase, which he obtained from the snail ''Helix pomatia''.<ref>{{cite thesis| first= A. |last= Hofmann | year=1929| title= Über den enzymatischen Abbau des Chitins und Chitosans| trans-title= On the enzymatic degradation of chitin and chitosan| publisher= University of Zurich |place= Zurich, Switzerland}}</ref><ref>{{cite journal| first1= P.| last1= Karrer |first2= A. |last2= Hofmann | year= 1929| title= Polysaccharide XXXIX. Über den enzymatischen Abbau von Chitin and Chitosan I| journal= Helvetica Chimica Acta| language= de| volume= 12| number= 1| pages= 616–637 | doi= 10.1002/hlca.19290120167}}</ref><ref>{{cite journal| first1= Nathaniel S.| last1= Finney| first2= Jay S.| last2= Siegel| year= 2008| title= In Memoriam: Albert Hofmann (1906-2008)| journal= CHIMIA| volume= 62| number= 5| pages= 444–447| url= http://www.zora.uzh.ch/9154/2/Siege_Finney_Hoffmann_2008V.pdf| publisher= University of Zurich| doi= 10.2533/chimia.2008.444| access-date= 2013-04-14| archive-date= 2013-06-16| archive-url= https://web.archive.org/web/20130616034406/http://www.zora.uzh.ch/9154/2/Siege_Finney_Hoffmann_2008V.pdf| url-status= dead}}</ref>

Chitin is a modified [[polysaccharide]] that contains nitrogen; it is [[biosynthesis|synthesized]] from units of [[N-acetylglucosamine|''N''-acetyl-<small>D</small>-glucosamine]] (to be precise, 2-(acetylamino)-2-deoxy-<small>D</small>-glucose). These units form covalent β-(1→4)-linkages (like the linkages between [[glucose]] units forming [[cellulose]]). Therefore, chitin may be described as [[cellulose]] with one [[hydroxyl]] group on each [[monomer]] replaced with an [[acetyl]] [[amine]] group. This allows for increased [[hydrogen bonding]] between adjacent [[polymers]], giving the chitin-polymer matrix increased strength.

In its pure, unmodified form, chitin is translucent, pliable, resilient, and quite tough. In most [[arthropod]]s, however, it is often modified, occurring largely as a component of [[composite material]]s, such as in [[sclerotin]], a tanned [[protein]]aceous matrix, which forms much of the [[exoskeleton]] of [[insect]]s. Combined with [[calcium carbonate]], as in the shells of [[crustacean]]s and [[mollusc]]s, chitin produces a much stronger composite. This composite material is much harder and stiffer than pure chitin, and is tougher and less brittle than pure [[calcium carbonate]].<ref name="Campbell">Campbell, N. A. (1996) ''Biology'' (4th edition) Benjamin Cummings, New Work. p.69 {{ISBN|0-8053-1957-3}}</ref> Another difference between pure and composite forms can be seen by comparing the flexible body wall of a [[caterpillar]] (mainly chitin) to the stiff, light [[elytron]] of a [[beetle]] (containing a large proportion of [[sclerotin]]).<ref>{{cite book | author = Gilbert, Lawrence I. | title = Insect development : morphogenesis, molting and metamorphosis | publisher = Elsevier/Academic Press | location = Amsterdam Boston | year = 2009 | isbn = 978-0-12-375136-2 }}</ref>

In butterfly wing scales, chitin is organized into stacks of [[gyroid]]s constructed of chitin [[photonic crystal]]s that produce various [[iridescent]] colors serving [[phenotype|phenotypic]] signaling and communication for mating and foraging.<ref name="wings">{{cite journal|journal=Proc Natl Acad Sci U S A|year=2010|volume=107|issue=26|pages=11676–81|doi=10.1073/pnas.0909616107|title=Structure, function, and self-assembly of single network gyroid (I4132) photonic crystals in butterfly wing scales|vauthors=Saranathan V, Osuji CO, Mochrie SG, Noh H, Narayanan S, Sandy A, Dufresne ER, Prum RO|pmid=20547870|pmc=2900708|bibcode=2010PNAS..10711676S|doi-access=free}}</ref> The elaborate chitin gyroid construction in butterfly wings creates a model of optical devices having potential for innovations in [[biomimicry]].<ref name="wings" /> [[Scarab beetle]]s in the genus ''[[Cyphochilus]]'' also utilize chitin to form extremely thin [[Scale (anatomy)|scales]] (five to fifteen [[micrometre]]s thick) that diffusely reflect white light. These scales are networks of randomly ordered filaments of chitin with diameters on the scale of hundreds of [[nanometre]]s, which serve to scatter light. The [[Scattering#Single and multiple scattering|multiple scattering]] of light is thought to play a role in the unusual whiteness of the scales.<ref>{{cite web|url=https://www.bbc.co.uk/news/science-environment-28811232|date=16 August 2014|title=Beetles' whiteness understood|author=Dasi Espuig M|publisher=BBC News: Science and Environment|access-date=15 November 2014}}</ref><ref name="Burresi">{{cite journal |first1 = Matteo |last1 = Burresi |first2 = Lorenzo |last2 = Cortese| first3 = Lorenzo |last3 = Pattelli | first4 = Mathias | last4 = Kolle | first5 = Peter | last5 = Vukusic | first6 = Diederik S. | last6 = Wiersma | first7 =  Ullrich | last7 = Steiner |first8 = Silvia | last8 = Vignolini |title=Bright-white beetle scales optimise multiple scattering of light |journal=Scientific Reports |volume = 4 |pages = 6075 |year = 2014 |doi = 10.1038/srep06075 | pmid=25123449 | pmc=4133710|bibcode = 2014NatSR...4E6075B }}</ref> In addition, some social wasps, such as ''[[Protopolybia chartergoides]]'', orally secrete material containing predominantly chitin to reinforce the outer nest envelopes, composed of paper.<ref>{{Cite journal |last1=Kudô |first1=K. |last2=Yamane |first2=Sô. |last3=Mateus |first3=S. |last4=Tsuchida |first4=K. |last5=Itô |first5=Y. |last6=Miyano |first6=S. |last7=Yamamoto |first7=H. |last8=Zucchi |first8=R. |date=2001-10-01 |title=Nest materials and some chemical characteristics of nests of a New World swarm-founding polistine wasp, Polybia paulista (Hymenoptera Vespidae) |url=https://doi.org/10.1080/08927014.2001.9522766 |journal=Ethology Ecology & Evolution |volume=13 |issue=4 |pages=351–360 |doi=10.1080/08927014.2001.9522766 |bibcode=2001EtEcE..13..351K |s2cid=86452110 |issn=0394-9370}}</ref>

[[Chitosan]] is produced commercially by [[deacetylation]] of chitin by treatment with [[sodium hydroxide]]. Chitosan has a wide range of biomedical applications including wound healing, drug delivery and tissue engineering.<ref name=":0" /><ref name=":1" /> Due to its specific intermolecular hydrogen bonding network, dissolving chitin in water is very difficult.<ref name=Bedian2017rev>{{cite journal|last1=Bedian|first1=L|last2=Villalba-Rodríguez|first2=AM|last3=Hernández-Vargas|first3=G|last4=Parra-Saldivar|first4=R|last5=Iqbal|first5=HM|title=Bio-based materials with novel characteristics for tissue engineering applications - A review.|journal=International Journal of Biological Macromolecules|date=May 2017|volume=98|pages=837–846|doi=10.1016/j.ijbiomac.2017.02.048|pmid=28223133}}</ref> Chitosan (with a degree of deacetylation of more than ~28%), on the other hand, can be dissolved in dilute acidic aqueous solutions below a pH of 6.0 such as acetic, formic and lactic acids. Chitosan with a degree of deacetylation greater than ~49% is soluble in water<ref>{{Cite journal |last1=Cho |first1=Yong-Woo |last2=Jang |first2=Jinho |last3=Park |first3=Chong Rae |last4=Ko |first4=Sohk-Won |date=2000-12-01 |title=Preparation and Solubility in Acid and Water of Partially Deacetylated Chitins |url=https://pubs.acs.org/doi/10.1021/bm000036j |journal=Biomacromolecules |language=en |volume=1 |issue=4 |pages=609–614 |doi=10.1021/bm000036j |pmid=11710189 |issn=1525-7797}}</ref><ref>{{Citation |last1=Rouhani Shirvan |first1=Anahita |title=5 - Recent advances in application of chitosan and its derivatives in functional finishing of textiles |date=2019-01-01 |url=https://www.sciencedirect.com/science/article/pii/B9780081024911000058 |work=The Impact and Prospects of Green Chemistry for Textile Technology |pages=107–133 |editor-last=Shahid-ul-Islam |access-date=2023-12-18 |series=The Textile Institute Book Series |publisher=Woodhead Publishing |isbn=978-0-08-102491-1 |last2=Shakeri |first2=Mina |last3=Bashari |first3=Azadeh |editor2-last=Butola |editor2-first=B. S.}}</ref>

===Humans and other mammals===
Humans and other mammals have [[chitinase]] and [[CHI3L1|chitinase-like proteins]] that can degrade chitin; they also possess several [[immune receptor]]s that can recognize chitin and its degradation products, initiating an [[immune response]].<ref name=Komi2017rev>{{cite journal|last1=Elieh Ali Komi|first1=D|last2=Sharma|first2=L|last3=Dela Cruz|first3=CS|title=Chitin and Its Effects on Inflammatory and Immune Responses.|journal=Clinical Reviews in Allergy & Immunology|volume=54|issue=2|pages=213–223|date=1 March 2017|doi=10.1007/s12016-017-8600-0|pmid=28251581|pmc=5680136}}</ref>

Chitin is sensed mostly in the lungs or [[gastrointestinal tract]] where it can activate the [[innate immune system]] through [[eosinophil]]s or  [[macrophage]]s, as well as an [[adaptive immune response]] through [[T helper]] cells.<ref name=Komi2017rev/> [[Keratinocyte]]s in skin can also react to chitin or chitin fragments.<ref name=Komi2017rev/>

===Plants===
Plants also have receptors that can cause a response to chitin, namely chitin elicitor receptor kinase 1 and chitin elicitor-binding protein.<ref name=Komi2017rev/>  The first chitin receptor was cloned in 2006.<ref name=Sanchez2015rev>{{cite journal|last1=Sánchez-Vallet|first1=A|last2=Mesters|first2=JR|last3=Thomma|first3=BP|title=The battle for chitin recognition in plant-microbe interactions.|journal=FEMS Microbiology Reviews|date=March 2015|volume=39|issue=2|pages=171–83|doi=10.1093/femsre/fuu003|pmid=25725011|issn=0168-6445|doi-access=free|hdl=20.500.11850/97275|hdl-access=free}}</ref>  When the receptors are activated by chitin, genes related to plant defense are expressed, and [[jasmonate]] hormones are activated, which in turn activate systemic defenses.<ref name=Sharp2013rev/>  [[Commensalism|Commensal]] fungi have ways to interact with the host immune response that, {{as of|2016|lc=y}}, were not well understood.<ref name=Sanchez2015rev/>

Some pathogens produce chitin-binding proteins that mask the chitin they shed from these receptors.<ref name=Sharp2013rev>{{cite journal|last1=Sharp|first1=Russell G.|title=A Review of the Applications of Chitin and Its Derivatives in Agriculture to Modify Plant-Microbial Interactions and Improve Crop Yields|journal=Agronomy|date=21 November 2013|volume=3|issue=4|pages=757–793|doi=10.3390/agronomy3040757|language=en|doi-access=free}}</ref><ref>{{cite journal|last1=Rovenich|first1=H|last2=Zuccaro|first2=A|last3=Thomma|first3=BP|title=Convergent evolution of filamentous microbes towards evasion of glycan-triggered immunity.|journal=The New Phytologist|date=December 2016|volume=212|issue=4|pages=896–901|doi=10.1111/nph.14064|pmid=27329426|doi-access=free}}</ref> ''[[Zymoseptoria tritici]]'' is an example of a fungal pathogen that has such blocking proteins; it is a major pest in [[wheat]] crops.<ref name=Kettles2016rev/>

==Fossil record==
{{for|more on the preservation potential of chitin and other biopolymers|taphonomy}}
Chitin was probably present in the exoskeletons of [[Cambrian]] arthropods such as [[trilobite]]s. The oldest preserved (intact) chitin samples thus far reported are dated to the [[Oligocene]], about {{ma|25}}, from specimens encased in [[amber]] where the chitin has not completely degraded.<ref name=Briggs1999>{{Cite journal
 | last = Briggs | first =  DEG
 | date = 29 January 1999
 | title = Molecular taphonomy of animal and plant cuticles: selective preservation and diagenesis
 | journal = Philosophical Transactions of the Royal Society B: Biological Sciences
 | volume = 354
 | issue = 1379
 | pages = 7–17
 | pmc = 1692454
 | doi = 10.1098/rstb.1999.0356
}}</ref>

== Uses ==

=== Agriculture ===
Chitin is a good inducer of plant [[plant defense against herbivory|defense mechanisms]] for controlling [[plant disease|diseases]].<ref>{{cite journal|pmc=2866471|year=2010|last1=El Hadrami|first1=A|title=Chitosan in plant protection|journal=Marine Drugs|volume=8|issue=4|pages=968–987|last2=Adam|first2=L. R.|last3=El Hadrami|first3=I|last4=Daayf|first4=F|doi=10.3390/md8040968|pmid=20479963|doi-access=free}}</ref> It has potential for use as a soil [[fertilizer]] or [[Soil conditioner|conditioner]] to improve fertility and plant resilience that may enhance crop yields.<ref>{{Cite journal|last1=Debode|first1=Jane|last2=De Tender|first2=Caroline|last3=Soltaninejad|first3=Saman|last4=Van Malderghem|first4=Cinzia|last5=Haegeman|first5=Annelies|last6=Van der Linden|first6=Inge|last7=Cottyn|first7=Bart|last8=Heyndrickx|first8=Marc|last9=Maes|first9=Martine|date=2016-04-21|title=Chitin mixed in potting soil alters lettuce growth, the survival of zoonotic bacteria on the leaves and associated rhizosphere microbiology|journal=Frontiers in Microbiology|volume=7|page=565|doi=10.3389/fmicb.2016.00565|issn=1664-302X|pmc=4838818|pmid=27148242|doi-access=free}}</ref><ref>{{Cite journal|last1=Sarathchandra|first1=S. U.|last2=Watson|first2=R. N.|last3=Cox|first3=N. R.|last4=di Menna|first4=M. E.|last5=Brown|first5=J. A.|last6=Burch|first6=G.|last7=Neville|first7=F. J.|date=1996-05-01|title=Effects of chitin amendment of soil on microorganisms, nematodes, and growth of white clover (''Trifolium repens'' L.) and perennial ryegrass (''Lolium perenne ''L.)|journal=Biology and Fertility of Soils|language=en|volume=22|issue=3|pages=221–226|doi=10.1007/BF00382516|bibcode=1996BioFS..22..221S |s2cid=32594901|issn=1432-0789}}</ref>

=== Industrial ===
Chitin is used in many industrial processes. Examples of the potential uses of chemically modified chitin in [[food processing]] include the formation of edible films and as an additive to thicken and stabilize foods and food emulsions.<ref>{{Cite journal|last1=Tzoumaki|first1=Maria V.|last2=Moschakis|first2=Thomas|last3=Kiosseoglou|first3=Vassilios|last4=Biliaderis|first4=Costas G.|date=August 2011|title=Oil-in-water emulsions stabilized by chitin nanocrystal particles|journal=Food Hydrocolloids|volume=25|issue=6|pages=1521–1529|doi=10.1016/j.foodhyd.2011.02.008|issn=0268-005X}}</ref><ref name=Shahidi>{{cite journal | last1 = Shahidi | first1 = F. | last2 = Arachchi | first2 = J.K.V. | last3 = Jeon | first3 = Y.-J. | year = 1999 | title = Food applications of chitin and chitosans | journal = Trends in Food Science & Technology | volume = 10 | issue = 2| pages = 37–51 | doi=10.1016/s0924-2244(99)00017-5}}</ref> Processes to [[Sizing|size]] and strengthen [[paper]] employ chitin and chitosan.<ref>{{Cite journal |last1=Hosokawa |first1=Jun |last2=Nishiyama |first2=Masashi |last3=Yoshihara |first3=Kazutoshi |last4=Kubo |first4=Takamasa |date=May 1990 |title=Biodegradable film derived from chitosan and homogenized cellulose |url=https://pubs.acs.org/doi/abs/10.1021/ie00101a015 |journal=Industrial & Engineering Chemistry Research |language=en |volume=29 |issue=5 |pages=800–805 |doi=10.1021/ie00101a015 |issn=0888-5885}}</ref><ref>{{Cite journal |last1=Gällstedt |first1=Mikael |last2=Brottman |first2=Angela |last3=Hedenqvist |first3=Mikael S. |date=July 2005 |title=Packaging-related properties of protein- and chitosan-coated paper |url=https://onlinelibrary.wiley.com/doi/10.1002/pts.685 |journal=Packaging Technology and Science |language=en |volume=18 |issue=4 |pages=161–170 |doi=10.1002/pts.685 |s2cid=96578009 |issn=0894-3214}}</ref>

==Research==
How chitin interacts with the [[immune system]] of plants and animals has been an active area of research, including the identity of key [[Receptor (biochemistry)|receptors]] with which chitin interacts, whether the size of chitin particles is relevant to the kind of immune response triggered, and mechanisms by which immune systems respond.<ref name="Gomez-Casado2016rev">{{Cite journal |last1=Gómez-Casado |first1=Cristina |last2=Díaz-Perales |first2=Araceli |last3=Hedenqvist |first3=Mikael S. |date=2016-10-01 |title=Allergen-Associated Immunomodulators: Modifying Allergy Outcome |url=https://doi.org/10.1007/s00005-016-0401-2 |journal=Archivum Immunologiae et Therapiae Experimentalis |language=en |volume=64 |issue=5 |pages=339–347 |doi=10.1007/s00005-016-0401-2 |issn=1661-4917 |pmid=27178664 |s2cid=15221318}}</ref><ref name=Kettles2016rev>{{cite journal|last1=Kettles|first1=GJ|last2=Kanyuka|first2=K|title=Dissecting the Molecular Interactions between Wheat and the Fungal Pathogen Zymoseptoria tritici|journal=Frontiers in Plant Science|date=15 April 2016|volume=7|pages=508|pmid=27148331|pmc=4832604|doi=10.3389/fpls.2016.00508|doi-access=free}}</ref> Chitin is deacetylated  chemically or enzymatically to produce [[chitosan]], a highly [[Biocompatibility|biocompatible]] polymer which has found a wide range of applications in the biomedical industry.<ref name=":0" /><ref>{{Cite journal |last1=Kapadnis |first1=Gaurav |last2=Dey |first2=Anomitra |last3=Dandekar |first3=Prajakta |last4=Jain |first4=Ratnesh |date=June 2019 |title=Effect of degree of deacetylation on solubility of low-molecular-weight chitosan produced via enzymatic breakdown of chitosan |url=https://onlinelibrary.wiley.com/doi/10.1002/pi.5795 |journal=Polymer International |language=en |volume=68 |issue=6 |pages=1054–1063 |doi=10.1002/pi.5795 |s2cid=104427459 |issn=0959-8103}}</ref><ref>{{Citation |last1=Desai |first1=Ranjeet |title=Review of the Structure of Chitosan in the Context of Other Sugar-Based Polymers |date=2021 |url=https://link.springer.com/10.1007/12_2021_89 |work=Chitosan for Biomaterials III |volume=287 |pages=23–74 |editor-last=Jayakumar |editor-first=R. |place=Cham |publisher=Springer International Publishing |language=en |doi=10.1007/12_2021_89 |isbn=978-3-030-83806-5 |access-date=2022-12-19 |last2=Pachpore |first2=Radhika |last3=Patil |first3=Ashwini |last4=Jain |first4=Ratnesh |last5=Dandekar |first5=Prajakta |s2cid=244341955 |editor2-last=Prabaharan |editor2-first=M.}}</ref> Chitin and chitosan have been explored as a [[vaccine adjuvant]] due to its ability to stimulate an immune response.<ref name=":0" /><ref name=Komi2017rev/>

Chitin and chitosan are under development as [[Tissue engineering#Scaffolds|scaffolds]] in studies of how tissue grows and how [[Wound healing|wounds heal]], and in efforts to invent better [[bandages]], [[surgical suture|surgical thread]], and materials for [[allotransplantation]].<ref name=":0" /><ref name=Bedian2017rev/><ref>{{cite journal|pmc=4557018|year=2015|last1=Cheung|first1=R. C.|title=Chitosan: An Update on Potential Biomedical and Pharmaceutical Applications|journal=Marine Drugs|volume=13|issue=8|pages=5156–5186|last2=Ng|first2=T. B.|last3=Wong|first3=J. H.|last4=Chan|first4=W. Y.|doi=10.3390/md13085156|pmid=26287217|doi-access=free}}</ref> [[Surgical suture|Sutures]] made of chitin have been experimentally developed, but their lack of elasticity and problems making thread have prevented commercial success so far.<ref>{{cite book|editor1-last=Ducheyne|editor1-first=Paul|editor2-last=Healy|editor2-first=Kevin|editor3-last=Hutmacher|editor3-first=Dietmar E.|editor4-last=Grainger|editor4-first=David W.|editor5-last=Kirkpatrick|editor5-first=C. James|title=Comprehensive biomaterials|date=2011|publisher=Elsevier|location=Amsterdam|isbn=9780080552941|page=230|url=https://books.google.com/books?id=oa8YpRsD1kkC&pg=RA1-PA230}}</ref>

[[Chitosan]] has been demonstrated and proposed to make a reproducible form of [[biodegradable]] plastic.<ref>{{cite web | title =Team creates bioplastic made from shrimp shells|url=https://phys.org/news/2014-05-team-bioplastic-shrimp-shells.html|date=6 May 2014|access-date=14 October 2024}}</ref> Chitin [[nanofiber]]s are extracted from crustacean waste and mushrooms for possible development of products in [[tissue engineering]], drug delivery and medicine.<ref name=":0" /><ref>{{cite journal|doi=10.3390/molecules191118367|pmid=25393598|pmc=6271128|title=Chitin and Chitosan Nanofibers: Preparation and Chemical Modifications|journal=Molecules|volume=19|issue=11|pages=18367–80|year=2014|last1=Ifuku|first1=Shinsuke|doi-access=free}}</ref>

Chitin has been proposed for use in building structures, tools, and other solid objects from a [[composite material]], combining chitin with [[Martian soil|Martian regolith]].<ref>{{Cite journal|last1=Shiwei|first1=Ng|last2=Dritsas|first2=Stylianos|last3=Fernandez|first3=Javier G.|date=September 16, 2020|title=Martian biolith: A bioinspired regolith composite for closed-loop extraterrestrial manufacturing|journal=PLOS ONE|volume=15|issue=9|pages=e0238606|doi=10.1371/journal.pone.0238606|pmid=32936806|pmc=7494075|bibcode=2020PLoSO..1538606S|doi-access=free}}</ref> To build this, the [[biopolymers]] in the chitin are suggested as the [[Binder (material)|binder]] for the regolith [[Aggregate (composite)|aggregate]] to form a [[concrete]]-like [[composite material]]. The authors believe that waste materials from food production (e.g. scales from fish, exoskeletons from crustaceans and insects, etc.) could be put to use as feedstock for manufacturing processes.

==See also==
* [[Chitobiose]]
* [[Lorica (biology)|Lorica]]
* [[Sporopollenin]]
* [[Tectin (secretion)|Tectin]]

== References ==
{{reflist|2}}

== External links ==
{{Scholia}}
* {{Commons category-inline|Chitin}}
* {{Wiktionary inline}}

{{carbohydrates}}
{{Insects in culture}}

{{Authority control}}

[[Category:Acetamides]]
[[Category:Biomolecules]]
[[Category:Biopesticides]]
[[Category:Polysaccharides]]