Chitosan

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Structural formula
Structural formula 100% deacetylated chitosan
General
Surname Chitosan
other names

Poliglusam; Polyglucosamine; Poly D -glucosamine; Poly (D) glucosamine; Deacetylchitin

CAS number 9012-76-4
Monomer Glucosamine , sometimes also N -acetylglucosamine
Molecular formula of the repeating unit C 6 H 11 NO 4
Molar mass of the repeating unit 161.15 g mol −1
PubChem 21896651
Type of polymer

Biopolymer

Brief description

light beige, linear polysaccharide , a polyaminosaccharide

Drug information
Drug class

Lipid adsorbers, wound healing, bacteriostatic

properties
Physical state

firmly

solubility

insoluble in water (depending on molecular weight) at pH> 6.4

safety instructions
GHS labeling of hazardous substances
no classification available
H and P phrases H: see above
P: see above
As far as possible and customary, SI units are used. Unless otherwise noted, the data given apply to standard conditions .

Schematic representation of the enzymatic synthesis of chitosan from chitin

Chitosan ( Greek χιτών "undergarment, shell, armor"), also Poliglusam or poly- D- glucosamine or polyglucosamine , is a biopolymer , a naturally occurring polyaminosaccharide , which is derived from chitin . Like this, it consists of β-1,4- glycosidically linked N-acetylglucosamine residues (exactly 2-acetamido-2-deoxy-β-D-glucopyranose residues). If there are more deacetylated 2-amino-2-deoxy-β-D-glucopyranose units in the overall molecule , it is called chitosan. This results in linear molecules that consist of around 2000  monomers . It was first obtained in 1859 by C. Rouget by boiling chitin with potassium hydroxide .

origin

Extraction

The main source of chitin for making chitosan is the shells of shrimp such as Pandalus borealis .

Chitosan is technically obtained from chitin by deacetylation . This can be done using (hot) caustic soda or enzymatically . Both processes are used technically, in terms of quantity the alkaline procedure is clearly in the foreground.

The degree of the resulting deacetylation can vary considerably: The deacetylation can take place completely or partially, which can result in a distribution of strongly deacetylated and less deacetylated areas or a homogeneous deacetylation distribution, which has considerable effects on the molecular shape. At the same time, due to this chemical intervention, the chain length of the polymer can decrease (depolymerization), whereby the solubility is improved and the viscosity is reduced. In addition, foreign atoms (e.g. heavy metals from caustic soda) can be introduced during the treatment. The end products can therefore differ considerably in their properties. Most clearly these differences are revealed in the solubility and viscosity z. B. a one percent chitosan solution in acetic acid .

Natural occurrence

In addition to chitin, some mushrooms also contain chitosan in their cell wall; Chitosan can be obtained directly from them. All known species such as B. Mucor rouxii , Absidia coerulea and Rhizopus oryzae belong to the order of the Mucorales .

properties

Chitosan is a colorless , amorphous , tough substance. Industrially produced, high molecular weight chitosan is soluble in dilute strong acids except sulfuric acid as well as in organic acids. The solubility in acids and at the same time poor solubility in neutral or alkaline pH is unique among biopolymers and therefore characterizing. With decreasing molar mass, however, chitosan (or oligo-glucosamine) is also soluble in water and even in alkalis .

Due to the free amino groups formed by the deacetylation, it is a polycation with a high charge density in non-alkaline solution . It's non-toxic, antibacterial, antiviral, and anti-allergenic. The LD 50 of chitosan is 16 g / kg body mass.

Fat binding

The fat binding through chitosan can be proven in the laboratory. Several patents and laboratory test descriptions are on the subject, alongside more or less effective products that are based on this principle. The efficiency of the fat binding is significant in terms of quantity, so that chitosan is generally used in biochemistry and disposal for removing oils , occasionally in drug approvals (e.g. in Spain) and in medical products and food supplements with the active ingredient name lipid adsorbent in many countries around the world, including all of them Member states of the EU that have been certified by independent and state-recognized experts.

The highest fat binding capacity was found in the biopolymer L112 with about 800 times its own mass.

Binding of suspended solids

Chitosan is used in water treatment , in wastewater treatment and in the beverage industry in a variety of ways and on an industrial scale to bind and precipitate suspended matter.

Other properties

Applications

Material use

The range of applications for this polymer is relatively broad and confusing (similar to cellulose and other biopolymers). Chitosan is mainly used as a filter medium (for water production or in sewage treatment plants ) and as a raw material for fibers, foams, membranes and foils ( bio-based plastic ). The positive properties in this area include the oxygen barrier effect, which enables a vacuum seal. A market-relevant production of bioplastics from chitosan does not yet exist.

With its adsorbing, hemostatic, anti-microbial and healing properties, chitosan is also used in medical devices (e.g. lipid adsorbents ( L112 ) or wound dressings). Chitosan is also used in toothpastes (e.g. Chitodent ), as a paper and cotton additive , and for removing cloudiness in the beverage industry. The pharmaceutical industry has been researching chitosan for a long time in order to use it for microencapsulation and the targeted release of pharmacological agents, including as a vector for gene therapy .

Chitosan applications
field of use usable applications Research applications
Health and biotechnology Help digest fats Enzyme immobilization
Cholesterol Reduction Immobilization in synthesis
Lipid binders for weight control Protein separation
Lipid separation Adsorption of endotoxins and nucleic acids
Wound pad Cell enrichment
artificial skin Glucose electrode
delayed drug release Chromatography material
degradable surgical filler (orthopedics, ophthalmology, dentistry) Binding of polymeric catalysts
Cell mobilization Cell immobilization (biotechnology)
Tumor therapy, immune stimulation semipermeable membrane
artificial vessels degradable sutures
artificial tear fluid Contact lens material
toothpaste Embedding media for electron microscopy
Agriculture and Food Sealing of food Coating agents
fungicidal seed treatment Preservation of seeds
Removal of dyes, solids, acids
Preservatives for fruits and vegetables Food packaging material
stabilizer
Food additive Fiber
Flavor
insecticide
Feed additive Feed additive in milk production
Nematocide
Coating / sealing of seeds and leaves
Fertilization Compost acceleration
sustained release of agrochemicals
Wood protection
textiles water-permeable fabrics
cosmetics Dental products
Oral care products
Hair care products
bacteriostatic preservatives
Skin care products
Water treatment Removal of organochemical components
Removal of heavy metals Wastewater treatment
Drinking water preparation Juice clarification (press)
Swimming pool water treatment Membranes for water desalination
Paper industry Air filtration material
Water filtration
degradable packaging materials
Binder for recycled cellulose
Surface smoothing agent
Copy papers
Photo papers
technology electronic elements Speaker cones

nutrition

In dietary supplements chitosan is a "fat blocker" used. The use as a food additive, however, is considered possibly illegal in some countries including Germany (in Austria, however, it is legal), since a dietary supplement may only supplement the food, but should not hinder its absorption. In countries where chitosan is allowed to be used in the food sector, such as the USA, several double-blind and randomized studies have shown that its effects can not be proven without a diet at the same time .

Individual evidence

  1. ↑ Sevda Şenel, Susan J. McClure: Potential applications of chitosan in veterinary medicine . In: Advanced Drug Delivery Reviews , 56, No. 10. June 23, 2004, pp. 1467-1480, doi : 10.1016 / j.addr.2004.02.007 .
  2. ↑ Rejane C.Goy, Sinara TBMorais, Odilio BGAssis: Evaluation of the antimicrobial activity of chitosan and its quaternized derivative on E. coli and S. aureus growth . In: Revista Brasileira de Farmacognosia , 26, No. 1, January / February 2016, 122–127, doi : 10.1016 / j.bjp.2015.09.010 .
  3. ↑ Caiqin Qin, Huirong Li, Qi Xiao, Yi Liu, Juncheng Zhu, Yumin Du: Water-solubility of chitosan and its antimicrobial activity . In: J Carbohydr. Polym. , 63, No. 3, 2006, pp. 367-374, doi : 10.1016 / j.carbpol.2005.09.023 .
  4. ↑ This substance has either not yet been classified with regard to its hazardousness or a reliable and citable source has not yet been found.
  5. ↑ Fereidoon Shahidi, Jozef Synowiecki: Isolation and characterization of nutrients and value-added products from snow crab (Chionoecetes opilio) and shrimp (Pandalus borealis) processing discards. In: J. Agric. Food Chem. , Vol. 39 (8), 1991, pp. 1527-1532, doi: 10.1021 / jf00008a032
  6. ↑ Rudolf Hänsel, Otto Sticher: Pharmakognosie - Phytopharmazie. 9th edition, Springer, Heidelberg 2009, ISBN 978-3-642-00962-4 , p. 593.
  7. ↑ Stoyko Fakirov, D. Bhattacharyya: Handbook of engineering biopolymers: homopolymers, blends and composites. Hanser Verlag, Munich 2007, ISBN 978-3-446-40591-2 , p. 818.
  8. ↑ K. Raisch, S. Rockway: Validation of a quantitative fat binding assay for polyglucosamine (L112). Nutrition 2005, Geneva (June 2, 2005).
  9. ↑ F. Poretti, T. Rosent, B. Körner and D. Vorwerk: Randomized investigation into the use of a chitosan coagulation pad for hemostasis in transbrachial angiographies . In: RöFo - Advances in the field of X-rays and imaging processes . tape 177 , no. 09 , 2005, p. 1260-1266 , doi : 10.1055 / s-2005-858328 .
  10. ↑ Karl Beese GmbH & Co .: The wound pad made of chitosan - a natural substance (PDF file; 1.1 MB).
  11. ↑ MV Bhaskara Reddy, J. Arul, P. Angers, L. Couture: Chitosan treatment of wheat seeds induces resistance to Fusarium graminearum and improves seed quality. In: J. Agric. Food Chem. , Vol. 47 (3), 1999, pp. 1208-1216.
  12. ↑ M. Eweis, SS Elkholy, MZ Elsabee: Antifungal efficacy of chitosan and its thiourea derivatives upon the growth of some sugar-beet pathogens. In: Int. J. Biol. Macromol. , Volume 38 (1), 2006, pp. 1-8.
  13. ↑ a b Rudolf Hansel, Otto Sticher: Pharmakognosie - Phytopharmazie - Google Books
  14. ^ Institute for Environmental Process Engineering (IUV) at the University of Bremen: Chitin, Chitosan on Wasser-Wissen.de.
  15. ↑ Organic yarn made from chitin at eierschale.wordpress.com, accessed on January 27, 2017.
  16. ^ Chitin & Chitosan - a Global Strategic Business Report . Global Industry Analysts, Inc. Archived from the original on April 15, 2010. Retrieved on July 1, 2012.
  17. ↑ Dietary supplements and functional foods: Fit-maker or consumer rubbish? (PDF) ak-tirol.com. Archived from the original on October 15, 2016. Info: The archive link was automatically inserted and has not yet been checked. Please check the original and archive link according to the instructions and then remove this notice. Retrieved July 1, 2012. @1@ 2Template: Webachiv / IABot / media.arbeiterkammer.at
  18. ↑ Federal Office for Consumer Protection and Food Safety: Dietary supplements with added chitosan (BVL 17/01/003). In: bvl.bund.de . June 26, 2017. Retrieved December 14, 2018 .
  19. ↑ “ There is considerable doubt that chitosan is effective for reducing body weight in humans. "According to Max H Pittler and Edzard Ernst : Dietary supplements for body-weight reduction. In: The American Journal of Clinical Nutrition 79 (2004), p. 530. ( PDF ).

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