Chitin And Chitosan Properties And Applications Pdf
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Offers a comprehensive guide to the isolation, properties and applications of chitin and chitosan. Chitin and Chitosan: Properties and Applications presents a comprehensive review of the isolation, properties and applications of chitin and chitosan.
- Chitin and chitosan: Chemistry, properties and applications
- Chitin and Chitosan: Production and Application of Versatile Biomedical Nanomaterials
- A review of chitin and chitosan applications
- Handbook of Chitin and Chitosan
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 and chitosan: Chemistry, properties and applications
For some years now, biopolymers have attracted great interest from both academia and industry. Some of them have been investigated for a long time, such as rubbers [ 1 ], the interest in others, such as starch, cellulose [ 2 ] or PHA [ 3 ], is mainly being driven by ecology concerns.
Chitin is somehow apart from this mainstreaming interest in biopolymers. Indeed, as the second major biopolymer worldwide after cellulose, it is mainly produced as a byproduct in shellfish industry. Therefore its production was less a concern for its valorization through different applications and subsequent purifications and derivatizations [4, 5 ].
Moreover, the N -acetyl group attached to the major part of the glucosamine monomeric units of chitin confers to it extremely poor solubility properties, making chitin difficult to process and thus limiting its potential applications [ 4 ].
To circumvent this issue, the hydrolysis of the acetyl group, also called deacetylation, can be applied Figure 2. When GlcN units are predominant compared to GlcNAc units, the biopolymer is no longer designated as chitin, but as chitosan. In this chapter the origin, different natural sources, subsequent issues related to the extraction and the purification of chitin, as well as its properties and applications are discussed.
Chitin was most probably discovered by an English scientist A. The interrogation on the difference between cellulose, produced by plants, and chitin produced by arthropods was initiated by Payen in [ 9 ].
In the same year Lassaigne found the presence of nitrogen in chitin, when working with the exoskeleton of silkworm butterfly, Bombix morii [ 9 ]. Then, Ledderhose identified glucosamine and acetic acid as structural units of chitin in , and Gilson confirmed glucosamine to be the repeated unit of chitin in [ 9 ]. The final chemical nature of chitin was elucidated by Purchase and Braun in [ 9 ]. Chitosan was first obtained from chitin by C. Rouget [ 10 ], when boiling chitin in a concentrated alkali solution and noticing that the resulting compound was soluble in organic acids.
Further, F. Hoppe-Seiler confirmed in that chitosan is the deacetylated form of chitin and thus gave it its actual name [ 10 ]. He discovered in that chitin adopts a stereotypic arrangement in arthropods [ 11 ].
In addition, non-crystalline, transient states have also been reported in a fungal system[ 12 ]. Further, the macroscopic arrangement of chitin layers and protein scaffolds surrounding them on a cholesteric helix was studied [ 13 ], a twisted plywood structure was thus found in the lobster Homarus americanus [ 14 ] and in the sheep crab Loxorhynchus grandis [ 15 ], it has also been reported to be responsible for the iridescence of the scarab beetle [ 16 ].
Chitin is present in the exoskeleton of arthropods [ 17 ], also in eukaryotic cells, such as those of fungi [ 18 ] and mushrooms [ 19 ]. It is also found in the iridophores reflective material in the epidermis and the eyes of certain arthropods and cephalopods [ 20 ]. One study [ 20 ] has even reported that the epidermal cuticle of a vertebrate, a fish named Paralipophrys trigloides , contains chitin; thus suggesting that chitin can also be produced by vertebrates.
As chitin is present in so many different species, it would be, of course, very tempting to use chitin for evolution and taxonomy of these different species, however to the best of our knowledge those studies have still to be done.
Also, a comparison between different properties, contents, etc. Despite this very large diversity of chitin sources, until now, mainly chitin from the shellfish industry has been explored. A few studies performed on insect chitin were mainly concerned with butterflies [ 22 ]. The insects exhibit a complex hierarchical structure, where each epidermal scale represents one color.
These scales are morphologically homogeneous and adherent to the wings in rows, which run parallel to the anterior-posterior axis of the wing [ 22 ]. Also, the determination of chitin content in its original source remains an issue. However, it strongly depends on the source and extraction procedure used, which may explain severe differences observed in the literature concerning some species, namely cuttlefish was found to have only 5.
As we have seen from the previous paragraph, the extraction and purification of chitin is not only important for the recovery of the desired product but also to characterize the chitin content in different sources. Up to now two main approaches for chitin extraction have been studied: chemical and biological approaches. Chemical extraction basically consists of two steps: acidic treatment for mineral elimination and basic treatment for protein elimination [27, 28 ].
The classical procedure can consist of an acidic treatment with HCl 1 M for 2 to 24 hours, followed with a basic treatment with NaOH 1 M for another 24 to 48 hours. The different parameters of these treatments can be tuned in order to adapt to a specific source of chitin or to combine different steps [17, 29 ]. Thus, for example, the mineral content is especially high within shellfish sources of chitin whereas lipid content is much higher in insects.
Therefore, the acidic treatment can be adjusted, especially through the solid-state approach, to combine the elimination of both these sources of contamination and to obtain highly crystalline chitosan [ 30 ]. Also the alkali concentration for the deproteination step is of specific interest, as at high temperature and concentration the reaction continues up to deacetylation and the obtained product is no longer chitin, but chitosan [ 31 ]. The utilization of acidic and basic conditions at high temperature may also damage the integrity of the chitin polymer, and oligosaccharides can be thus obtained.
It can present advantages for some applications, shorter chains inducing better solubility, but also drawbacks of chain alteration [ 18 ]. Another issue consists of a very poor ability to analyze the obtained product, several attempts through infrared [ 32 ], diffraction [ 25 ], fluorescence [ 33 ] or NMR [21, 26 ] techniques were made, however they did not give sufficiently satisfying results [ 25 , 28 , 29 ], and only a combination of several of these approaches allows the confirmation of the structure and purity of the chitin.
Another aspect of the purification of chitin is its color. Indeed, melanins and other sclerotins [ 12 , 17 ] attached to the exoskeleton of arthropods or other chitin sources make it difficult to obtain a pure white chitin at the end of the process, therefore bleaching agents, such as hydrogen peroxide, are often used to finalize the chitin purification [ 34 ].
The main drawback of the utilization of chemical extraction remains however its energetic and environmental impact due to the extensive utilization of acidic and basic solutions requiring further neutralization and elimination [ 34 ].
The biological methods for the extraction of chitin have been developed recently [ 34 ]. They can use either purified enzymes [ 36 , 37 ] or whole microorganisms [ 38 ]. Although more environment friendly, these methods remain less efficient, one of the main reasons being the up to now poor understanding of the main covalent links between chitin and the surrounding proteins and melanins [ 12 , 17 ].
Indeed, the main enzymes used for the purification of chitins are proteases, they cut protein bonds to give peptides and amino acids, however they cannot liberate chitin from catechols or even amino acids directly attached to it. In this case, it becomes even more difficult to avoid bleaching steps, thus reducing the scope of pure biological extraction and making it much more biochemical [ 34 ].
As neither chemical nor biological methods are completely satisfying for now, several academic teams and industrial companies are still working on their improvements. This extraction stage is, indeed, essential for chitin and chitosan to fulfill the huge potential those molecules can present.
Chitin and chitosan have recently been reported to present several properties such as biocompatibility [ 39 ], biodegradation [ 40 ], scavenging of heavy metal [ 41 ] and of cholesterol or other fats [ 42 ], antimicrobial and antioxidative behaviors [ 43 , 44 ], etc. However, we have to acknowledge that even if those biopolymers seem very promising, until now, the actual applications remain rather limited.
This can be explained by different aspects: the difficulty of extraction and purification of the original chitin, the necessary transformation of chitin to chitosan followed by the derivatization of the latter for most of applications [ 45 — 47 ], etc. Also, some of the previously mentioned assertions appeared less obvious that they seemed at first glance, for example, it would be difficult for the same molecule to present antimicrobial and biodegradation properties, actually if the antimicrobial aspect of chitin and chitosan seems to be proven, their biodegradation appears much more doubtful [ 48 ].
Similarly, the fact that chitin is difficult to purify, namely from fats, does not necessarily mean that it makes it good candidate for lowering cholesterol in blood. For all the reasons mentioned above, we will focus our attention in this chapter mainly on biomedical, agricultural, materials and water purification applications of chitin and chitosan.
The main biomedical applications of chitosan are in wound healing. This application combines two of the most interesting properties of chitosan: antimicrobial behavior and biocompatibility [ 4 ]. These products have been on the market since the early s, mainly in Asia and North America, but also in Europe, however to a lesser extent.
Some other biomedical applications of chitosan were also studied, such as bone substitutes [ 4 , 49 ], blood interactions [ 4 , 50 ], drugs vectorization [ 4 ], implants [ 51 ], or anti-inflammatory [ 52 , 53 ], antihypertensive [ 54 ] and anticancer [ 55 ] drugs; however most of these applications have not yet reached the actual market of biomedical products.
Finally, chitosan was also shown to be active against cryptosporidiosis in goats, significantly reducing the excretion of oocysts of C. Chitin and chitosan were reported to contribute to the protection of plants against pathogens. However, in this application, chitin and chitosan were described to play very different roles.
Chitin was reported to contribute to the protection of seeds, mainly by allowing the growth of microbial pesticides, such as Trichoderma harzianum P1, which was reported to be active against foliar disease. The addition of chitin to the medium specifically contributed to the growth of T. Chitosan was described to act as an elicitor, indeed, several plants possess chitinolytic enzymes, which help them to defend themselves against pathogen aggressors, such as fungi.
The introduction of chitosan in the growth medium stimulates the production of chitinolytic enzymes in plants, thus making them more resistant towards their natural aggressors [ 58 , 59 ]. For a long time chitosan as a material was used as a plastic for the production of antimicrobial films for the food industry, i. Several attempts to produce novel biofunctional materials were also made, such as grafting of ester derivatives of poly ethylene glycol PEG [ 61 ] or phosphomethylation [ 62 , 63 ].
More recently, some novel applications received greater interest, among them the utilization of chitosan as a catalyst support is of particular interest. It thus contributes to the implementation of green chemistry principles by minimizing the amount of required product — catalytic and not stoichiometric proportions, and utilization of renewable raw materials — second most abundant biopolymer worldwide. The quality of water remains one of the huge issues humanity is currently facing. Access to pure water in some parts of the world remains difficult, thus generating malnutrition, diseases, and even military conflicts.
Therefore the purification of water that was initially unsuitable for use or polluted is of crucial importance. To contribute to the wellbeing of a larger population the chosen water treatment techniques have to be technically and economically efficient. Different techniques are usually applied to water purification, such as scavenging, adsorption, flocculation or biological treatments.
Chitosan can be applied for adsorption [ 68 , 69 ] and flocculation [ 70 ] purposes, the fact that it is an environment friendly compound, very abundant and rather cheap makes it a solution of choice in certain cases. Thus chitosan was shown to be particularly efficient for the flocculation of cardboard-mill secondary biological wastewater [ 70 ], unfortunately the actual applications in industry remain rather rare, as concurrent flocculating agents are cheaper.
Indeed, even if chitosan shows better properties, the traditional cheaper products are sufficient to fulfill current regulatory frameworks. Chitin is a second most abundant biopolymer on Earth after cellulose. Present in several species, it is, until now, mainly obtained from the discards of the shellfish industry. Its extraction and purification as well as the reliability of available sources remain an issue and unfortunately impacts its widespread applications.
Also, as chitin has a rather poor range of applications that can be exploited, mainly focused on the agricultural area, it has to be transformed by deacetylation to chitosan, and sometimes even further by derivatization of the latter. Despite extremely interesting properties, such as biocompatibility or antimicrobial behavior, the applications of chitosan in the biomedical area remain limited, mainly due to the extreme difficulty to access sufficient purity and source reliability of the biopolymer.
The materials applications until now are rather limited, mainly due to the cost of the product, which remains higher than that of petroleum based polymers with similar properties.
The applications in the agricultural fields seem very promising but require more research and development to achieve significant results, therefore the main utilization of chitosan is now the purification of water, achieved by scavenging of heavy metal residues.
Finally, for the widespread utilization of these truly very promising biopolymers, beside strong scientific developments, intellectual rigor is also mandatory, to promote only actual properties and to avoid attributing fashionable but not proven ones. De Gruyter , isbn —3—11——7. Search in Google Scholar. Polyhydroxyalkanoates: structure, properties and sources.
Chitin: fulfilling a biomaterials promise. Elsevier Insights, 2nd Ed. Crustacea processing waste management. Seafish , , 1— Chitin research revisited.
Mar Drugs , , 8, — and refer-ences cited therein.
Chitin and Chitosan: Production and Application of Versatile Biomedical Nanomaterials
Offers a comprehensive guide to the isolation, properties and applications of chitin and chitosan Chitin and Chitosan: Properties and Applications presents a comprehensive review of the isolation, properties and applications of chitin and chitosan. These promising biomaterials have the potential to be broadly applied and there is a growing market for these biopolymers in areas such as medical and pharmaceutical, packaging, agricultural, textile, cosmetics, nanoparticles and more. The authors - noted experts in the field - explore the isolation, characterization and the physical and chemical properties of chitin and chitosan. They also examine their properties such as hydrogels, immunomodulation and biotechnology, antimicrobial activity and chemical enzymatic modifications. The book offers an analysis of the myriad medical and pharmaceutical applications as well as a review of applications in other areas. In addition, the authors discuss regulations, markets and perspectives for the use of chitin and chitosan. This important book: Offers a thorough review of the isolation, properties and applications of chitin and chitosan.
A review of chitin and chitosan applications
Corresponding Author. This review characterizes the most common natural polysaccharides and the presence of huge structural tendencies for the production of biologically active compounds, which have innovative characteristics and functions of different applications, especially in the field of biomedicine. Their applications are also demonstrated, such as: biomedicine antioxidant, anti-bacterial, anti-fungal anti-viral, hepatoprotective, cardiovascular, anti-hypercholesterolemia, anti-parasitic, anti-diabetic, detoxification, anti-tumor and immunomodulating , agriculture, food industry, textile industry, and paper making. Interestingly, the relationship between biological activity and chemical structure is elucidated for glucan, chitin, chitosan molecules with various degree of acetylation DA and Mw. In conclusion, many vital industrial and medical applications are offered, for chitin, chitosan and glucan, and they are known as vital and a novel biological compound, which have occupation priority of their compatibility low immunogenicity and nontoxic and biodegradation with non-toxic.
For some years now, biopolymers have attracted great interest from both academia and industry. Some of them have been investigated for a long time, such as rubbers [ 1 ], the interest in others, such as starch, cellulose [ 2 ] or PHA [ 3 ], is mainly being driven by ecology concerns. Chitin is somehow apart from this mainstreaming interest in biopolymers.
The Handbook of Chitin and Chitosan: Preparation and Properties, Volume One, is a must-read for polymer chemists, physicists and engineers interested in the development of ecofriendly micro and nanostructured functional materials based on chitin and their various applications. The book addresses the entirety of working with these materials, from their isolation, preparation and properties, through composites, nanomaterials, manufacturing and characterizations. Polymer chemists, engineers and technologists. Researchers, graduates and postgraduates in the fields of materials science, biomaterials and medicines.
Handbook of Chitin and Chitosan
Skip to search form Skip to main content You are currently offline. Some features of the site may not work correctly. Dutta and J. Dutta and V. Dutta , J. Dutta , V.
Biopolymers like chitin and chitosan exhibit diverse properties that open up a wide-ranging of applications in various sectors especially in biomedical science. The latest advances in the biomedical research are important emerging trends that hold a great promise in wound-healing management products. Chitin and chitosan are considered as useful biocompatible materials to be used in a medical device to treat, augment or replace any tissue, organ, or function of the body. A body of recent studies suggests that chitosan and its derivatives are promising candidates for supporting materials in tissue engineering applications. This review article is mainly focused on the contemporary research on chitin and chitosan towards their applications in numerous biomedical fields namely tissue engineering, artificial kidney, skin, bone, cartilage, liver, nerve, tendon, wound-healing, burn treatment and some other useful purposes.
Стратмор вскинул брови. - С какой целью. - Танкадо мог посылать фиктивные сообщения на неиспользованный адрес в надежде, что мы его обнаружим и решим, что он обеспечил себе защиту. В таком случае ему не нужно будет передавать пароль кому-то. Возможно, он работал в одиночку. Стратмор хмыкнул. Мысль Сьюзан показалась ему достойной внимания.
В центре находился красный кружок с надписью БАЗА, вокруг которого располагались пять концентрических окружностей разной толщины и разного цвета. Внешняя окружность была затуманена и казалась почти прозрачной.
Она чувствовала, как к ее горлу подступает тошнота. Его руки двигались по ее груди. Сьюзан ничего не чувствовала. Неужели он ее трогает. Она не сразу поняла, что он пытается застегнуть верхнюю пуговицу ее блузки.
Он дожил до тридцати пяти лет, а сердце у него прыгало, как у влюбленного мальчишки. Никогда еще его не влекло ни к одной женщине. Изящные европейские черты лица и карие глаза делали Сьюзан похожей на модель, рекламирующую косметику Эсте Лаудер. Худоба и неловкость подростка бесследно исчезли.