Chitin Fibers Research Articles

Ultrastructure of the Interlamellar Membranes of the Nacre of the Bivalve Pteria hirundo, Determined by Immunolabelling.

The current model for the ultrastructure of the interlamellar membranes of molluscan nacre imply that they consist of a core of aligned chitin fibers surrounded on both sides by acidic proteins. This model was based on observations taken on previously demineralized shells, where the original structure had disappeared. Despite other earlier claims, no direct observations exist in which the different components can be unequivocally discriminated. We have applied different labeling protocols on non-demineralized nacreous shells of the bivalve Pteria. With this method, we have revealed the disposition and nature of the different fibers of the interlamellar membranes that can be observed on the surface of the nacreous shell of the bivalve Pteria hirundo by high resolution scanning electron microscopy (SEM). The minor chitin component consists of very thin fibers with a high aspect ratio and which are seemingly disoriented. Each fiber has a protein coat, which probably forms a complex with the chitin. The chitin-protein-complex fibers are embedded in an additional proteinaceous matrix. This is the first time in which the sizes, positions and distribution of the chitin fibers have been observed in situ.

CDNA cloning and analysis of alanine-rich cuticle protein gene of common fouling barnacle, Balanus amphitrite

Article history: Received on: 16/03/2015 Revised on: 31/03/2015 Accepted on: 22/04/2015 Available online: 20/05/2015 Hard cuticle of insects is a complex structure composed mainly of several proteins and chitin fibers. Cuticular proteins are important as presence of different cuticular proteins confer different mechanical properties to the exoskeletons of insects. Hence, there is growing interest in studying cuticular proteins as bioengineering of these proteins may help in synthesis of biomaterials for various applications. Till date many cuticle proteins have been identified from insects. These proteins show presence of characteristic motifs in them such as R&R motif, extended R&R motif, AAP (V/L) motif etc. We have identified one of such putative cuticle protein encoding gene from common fouling barnacle, Balanus amphitrite by cDNA cloning and sequencing. The gene was found to encode an open reading frame (ORF) of 102 amino acids. The deduced protein sequence was found rich in alanine forming almost 22% of the total amino acids. Other two predominant amino acids, valine and proline together contributed ~23% of total amino acids. The hydropathy plot of the amino acid sequence showed presence of two hydrophobic regions surrounding central hydrophilic region. The protein sequence showed presence of three characteristic YHAAP (V/L) motifs at the C-terminus.

Layer-by-layer self-assembled thin films of chitin fibers and heparin with anti-thrombus characteristics

Layer-by-layer assembled films of chitin nanofibers and heparin with anti-thrombus characteristics.

ChtVis-Tomato, a genetic reporter for in vivo visualization of chitin deposition in Drosophila.

Chitin is a polymer of N-acetylglucosamine that is abundant and widely found in the biological world. It is an important constituent of the cuticular exoskeleton that plays a key role in the insect life cycle. To date, the study of chitin deposition during cuticle formation has been limited by the lack of a method to detect it in living organisms. To overcome this limitation, we have developed ChtVis-Tomato, an in vivo reporter for chitin in Drosophila. ChtVis-Tomato encodes a fusion protein that contains an apical secretion signal, a chitin-binding domain (CBD), a fluorescent protein and a cleavage site to release it from the plasma membrane. The chitin reporter allowed us to study chitin deposition in time lapse experiments and by using it we have identified unexpected deposits of chitin fibers in Drosophila pupae. ChtVis-Tomato should facilitate future studies on chitin in Drosophila and other insects.

Hole–pin joining structure with fiber-round-hole distribution of lobster cuticle and biomimetic study

Observations of the cuticle of the Boston Spiny Lobster using scanning electron microscope (SEM) show that it is a natural biocomposite consisting of chitin fibers and sclerotic-protein matrix with hierarchical and helicoidal structure. The SEM images also indicate that there is a hole–pin joining structure in the cuticle. In this joining structure, the chitin fibers in the neighborhood of the joining holes continuously round the holes to form a fiber-round-hole distribution. The maximum pullout force of the fibers in the fiber-round-hole distribution, which is closely related to the fracture toughness of the cuticle, is investigated and compared with that of the fibers in non-fiber-round-hole distribution based on their representative models. It is revealed that the maximum pullout force of the fibers in the fiber-round-hole distribution is significantly larger than that of the fibers in the non-fiber-round-hole distribution, and that a larger diameter of the hole results in a larger difference in the maximum pullout forces of the fibers between the two kinds of the fiber distributions. Inspired by the fiber-round-hole distribution found in the cuticle, composite specimens with the fiber-round-hole distribution were fabricated with a special mold and process to mirror the fiber-round-hole distribution. The fracture toughness of the biomimetic composite specimens is tested and compared with that of the conventional composite specimens with the non-fiber-round-hole distribution. It is demonstrated that the fracture toughness of the biomimetic composite specimens with the fiber-round-hole distribution is significantly larger than that of the conventional composite specimens with the non-fiber-round-hole distribution.

Crustacean-derived biomimetic components and nanostructured composites.

Over millions of years, the crustacean exoskeleton has evolved into a rigid, tough, and complex cuticle that is used for structural support, mobility, protection of vital organs, and defense against predation. The crustacean cuticle is characterized by a hierarchically arranged chitin fiber scaffold, mineralized predominately by calcium carbonate and/or calcium phosphate. The structural organization of the mineral and organic within the cuticle occurs over multiple length scales, resulting in a strong and tough biological composite. Here, the ultrastructural details observed in three species of crustacean are reviewed: the American lobster (Homarus americanus), the edible crab (Cancer pagurus), and the peacock mantis shrimp (Odontodactylus scyllarus). The Review concludes with a discussion of recent advances in the development of biomimetics with controlled organic scaffolding, mineralization, and the construction of nanoscale composites, inspired by the organization and formation of the crustacean cuticle.

Effect of Acidity on Chitin–Protein Interface: A Molecular Dynamics Study

Chitin–protein interfaces exist in many biological materials such as cuticles of insects and crustaceans, which are main commercial sources of chitin fiber. In industrial processing, the extraction of chitin from these sources is achieved via acidic and alkaline treatments. As the acidity changes, the ionizable groups of protein undergo protonation/deprotonation, which may vary the mechanical properties of chitin–protein interface. In order to study the effect of acidity on this interface, we perform a series of molecular dynamics simulations and measure the adhesion strength between chitin and a short peptide sequence under both acidic and alkaline conditions, where the two termini are modified to accommodate the environment. The results indicate that the protonation state of terminus has a significant influence on the adhesion with chitin. Based on our simple model and its results, we analyze the roles of termini in the formation of hydrogen bonds and elucidate some atomistic mechanisms behind the acidity effect on chitin–protein interface, which may spotlight the engineering on biological materials with similar interfaces.

Development of Functional Knitted Fabrics Made from Bi-Component Chitin and Wool Fibre

The paper briefly introduces main characteristics of chitin fibre, primary issues of wool knitted materials application in next-to-skin apparel and design of applying chitin to different wool fibre fabric. It focuses on design processes of knitted fabric, including principle of materials proportion and specification, and technique of fabric texture design. Notices regarding needles arrangement, knitting notation, and cam-setting etc. during fabric knitting, as well as production basis are also presented hereon.

Novel fibers fabricated directly from chitin solution and their application as wound dressing

For the first time, pure chitin fibers with relatively high strength, lustrous surface and circular cross section were spun directly from chitin solution dissolved in an NaOH-urea aqueous system with freezing. Subsequently, chitin nonwoven fabrics were constructed from the fresh wet fibers by hot pressing, and tested as wound dressings, showing excellent ability to accelerate healing, owing to the retainment of the intrinsic α-chitin structure.

Surface modification of ionic liquid-spun chitin fibers for the extraction of uranium from seawater: seeking the strength of chitin and the chemical functionality of chitosan

A platform was developed for the surface modification of ionic liquid-spun chitin fibers, that provides the physical properties of chitin with chitosan's functional properties on the surface.

Properties of polymethyl methacrylate-based nanocomposites: Reinforced with ultra-long chitin nanofiber extracted from crab shells

Ultra-long chitin nanofibers were incorporated into polymethyl methacrylate (PMMA) resin to prepared PMMA/Chitin nanocomposites with improved properties. Transmission electron microscopy (TEM) images showed that through the introduced 4-step all-mechanical treatment, the average aspect ratio of the obtained chitin fiber was up to 1000 with the length at dozens of micron range. Due to the laminated structure formed by “layer-by-layer” effect, tensile strength and Young’s modulus of the prepared composite were significantly enhanced after the filling of chitin nanofibers, as compared with neat PMMA. Light transmittance test indicated that increasing the fiber content causes little light scattering because the nano-scalar network which is smaller enough than the visible wavelength could well preserve the original transparency of PMMA. Furthermore, chitin nanofiber film with extremely low thermal expansion improved the thermal stability of PMMA in a great degree. This could lead to various commercial applications including flexible electronic printing, organic thin-film photovoltaic devices, and is a significantly environmental move towards the sustainable utilization of marine-river crab shell wastes.

Research on the Properties of Functional Chitin Fiber

Chitin fiber is a new type of green functional textile materials that can biodegradation, these years more and more people pay great attention to it for its excellent properties of antibacterial, moisture-absorption propertyetc etc.. On the basis of experimental examination, the length wise appearance and cross section appearance , the tensile properties, the moisture-absorbency, property , crystallinity, crientation, mass specific resistance and antibacterial property etc of the Chitin fiber are studied in this paper. The conclusions obtained in this paper have important reference value to the development of Chitin fiber product and its processing.

Oligomerization of the chitin synthase Chs3 is monitored at the Golgi and affects its endocytic recycling

Chs3, the catalytic subunit of chitin synthase III in Saccharomyces cerevisiae, is a complex polytopic membrane protein whose plasma membrane expression is tightly controlled: export from the ER requires interaction with Chs7; exit from the Golgi is dependent on the exomer complex, and precise bud neck localization relies on endocytosis. Moreover, Chs3 is efficiently recycled from endosomes to the TGN in an AP-1-dependent manner. Here we show that the export of Chs3 requires the cargo receptor Erv14, in a step that is independent of Chs7. Chs3 oligomerized in the ER through its N-terminal cytosolic region. However, the truncated (Δ126)Chs3 was still exported by Erv14, but was sent back from the Golgi to the ER in a COPI- and Rer1-dependent manner. A subset of the oligomerization-deficient Chs3 proteins evaded Golgi quality control and reached the plasma membrane, where they were enzymatically active but poorly endocytosed. This resulted in high CSIII levels, but calcofluor white resistance, explained by the reduced intercalation of calcofluor white between nascent chitin fibres. Our data show that the oligomerization of Chs3 through its N-terminus is essential for proper protein trafficking and chitin synthesis and is therefore monitored intracellularly.

New generation butyric-acetate copolymer of chitin (BOC) fibres with ceramic HAp and TCP nanoadditives for the manufacture of fibrous composite materials

An investigation was made of the effect of basic spinning process parameters on the structure and properties of butyric-acetate copolymer of chitin (BOC) fibres. It was found that, considering the resulting tenacity of 20.3 cN/tex simultaneously with high water sorption and retention properties, it is favourable for the BOC fibre spinning process to be carried out with 1 % HAp or TCP nanoadditive. Furthermore, when 3 % of the HAp or TCP nanoadditive is incorporated into the BOC fibre material, no significant changes in the crystal structure occur compared with fibres without the nanoadditives, formed in similar conditions. Analysis of the porous structure and the properties of the surface of BOC fibres with HAp or TCP nanoadditive shows that the parameters are favourable for their medical application.

Preparation of chitin–silica composites by in vitro silicification of two-dimensional Ianthella basta demosponge chitinous scaffolds under modified Stöber conditions

Chitin is a biopolymer found in cell walls of various fungi and skeletal structures of numerous invertebrates. The occurrence of chitin within calcium- and silica-containing biominerals has inspired development of chitin-based hybrids and composites in vitro with specific physico-chemical and material properties. We show here for the first time that the two-dimensional α-chitin scaffolds isolated from the skeletons of marine demosponge Ianthella basta can be effectively silicified by the two-step method with the use of Stöber silica micro- and nanodispersions under Extreme Biomimetic conditions. The chitin–silica composites obtained at 120°C were characterized by the presence of spherical SiO2 particles homogeneously distributed over the chitin fibers, which probably follows from the compatibility of Si–OH groups to the hydroxyl groups of chitin. The biocomposites obtained were characterized by various analytical techniques such as energy dispersive spectrometry, scanning electron microscopy, thermogravimetric/differential thermal analyses as well as X-ray photoelectron spectroscopy, Fourier transform infrared and Raman spectroscopy to determine possible interactions between silica and chitin molecule. The results presented proved that the character and course of the in vitro chitin silicification in Stöber dispersions depended considerably on the degree of hydrolysis of the SiO2 precursor.

The Performance and Development Trends of Low-Carbon Textile Materials

The impact of the deteriorating environmental issues on human survival and constraints on social development promotes awakening of environmental awareness, while the expanding of low-carbon consumption market and low-carbon technology revolution triggered by low-carbon economy model, has established a new direction for the garment industry, that is, low-carbon fashion. In order to comply with the objectives of environmental sustainable development, exploiting environmental and low-carbon textile materials has become one of the trends for textiles in 21st century. Regarding carbon materials as the core, this paper firstly discusses the concept and research significance of low-carbon materials, then enumerates several new low-carbon textile materials’ performance and applications: hemp fiber, colored cotton fabric, bamboo fiber, chitin fiber, etc. Through these listed above, it indicates the trend for low-carbon textile materials.

Fibre helicoidally rounding hole of tumblebug’s elytra and extrusion strength of biomimetic composite

Scanning electron microscope (SEM) observation shows that tumblebug’s elytra are a kind of chitin fibre reinforced biocomposite. In the biocomposite, the chitin fibres possess a laminated microstructure and distribute in a kind of particular helicoidal pattern. More careful observation indicates that there is a kind of fibre helicoidally rounding hole in the elytra. Based on the SEM observation, a kind of composite laminate with biomimetic fibre helicoidally rounding hole was fabricated through a special mould and moulding process. The extrusion strength of the biomimetic fibre helicoidally rounding hole was investigated and compared with that of the conventional drilling hole in the composite laminate. It is shown that the extrusion strength of the biomimetic fibre helicoidally rounding hole is markedly larger than that of the conventional drilling hole.

Preparation and Properties of Optically Transparent Chitin Nanofibers Sheet by Different Simple Mechanical Methods

Chitin nanofibers were prepared from commercially available dried chitin powders by different simple mechanical methods under acid conditions after removal of minerals and proteins. The fibrillated chitin samples were observed by FE-SEM and there was a fine network structure formed by chitin nanofibes with a width of approximately 10-50 nm and high aspect ratio. The mechanical treatment under acid conditions was crucial to facilitate the fibrillation of chitin fibers into nanofibers. The high pressure homogenization in combination with grinding was used to obtain the most transparent chitin nanofibers sheet with a transmittance of 88.5% and tensile strength of 82.34MPa, and the sheet even had a Young’s modulus of 6.17GPa. Thus, chitin nanofibers provide excellent potential as reinforcement of transparent flexible composites to improve the properties of nanocomposites.

Electrospinning of chitin nanofibers directly from an ionic liquid extract of shrimp shells

High molecular weight chitin fibers were electrospun in a one-pot process directly from a 1-ethyl-3-methylimidazolium acetate solution of chitin extracted from dried shrimp shell. Such a technology obviates the need not only for the many chemicals and the energy used in industrial isolation of chitin from crustacean shells but also saves the chemicals, energy, and time needed to prepare chitin spinning dopes.

Species-specific shells: Chitin synthases and cell mechanics in molluscs

AbstractThe size, morphology and species-specific texture of mollusc shell biominerals is one of the unresolved questions in nature. In search of molecular control principles, chitin has been identified by Weiner and Traub (FEBS Lett. 1980, 111:311–316) as one of the organic compounds with a defined co-organization with mineral phases. Chitin fibers can be aligned with certain mineralogical axes of crystalline calcium carbonate in a species-specific manner. These original observations motivated the functional characterization of chitin forming enzymes in molluscs. The full-length cDNA cloning of mollusc chitin synthases identified unique myosin domains as part of the biological control system. The potential impact of molecular motors and other conserved domains of these complex transmembrane enzymes on the evolution of shell biomineralization is investigated and discussed in this article.