Chitin Research Articles

Corn stalk/AgNPs modified chitin composite hemostatic sponge with high absorbency, rapid shape recovery and promoting wound healing ability

• Loose corn stalk (CS) is used to adjust the structure and property of chitin (CH) sponge. • AgNPs reduced and stabilized by CS is used to endow CH with antibacterial activity. • CH/CS/AgNPs sponge exhibit through-hole porous structure and soft compressibility. • CH/CS/AgNPs show higher blood absorption and hemostatic efficiency than CH and PVF. • CH/CS/AgNPs don’t cause inflammation and exhibit biocompatibility and nontoxicity. Uncontrolled hemorrhage before hospitalization and infection are two great challenges for the safety of human life. Although chitin (CH) is a kind of effective hemostatic materials, it presents poor softness and antibacterial activity, which hinders its potential application. Herein, for the first time, loose corn stalk (CS) and silver nanoparticles (AgNPs) were used to adjust the dense structures and poor antibacterial activities of solo chitin sponge. And then the crosslinked CH/CS/AgNPs sponge was used as antibacterial hemostatic material. The results show that the blood absorbing ratio of CH/CS/AgNPs was 2.4-fold and 2.7-fold higher than those of solo CH and commercial polyvinyl formal sponge (PVF), respectively. In vitro blood clotting index (19%) of CH/CS/AgNPs was also lower than those of solo CH (45%) and PVF (65%). In vivo rat liver injury results further indicate that the sponge had high hemostatic efficiency without causing inflammation. Besides, the cytotoxicity assay and hemolysis (3.18%) exhibited favorable biocompatibility and nontoxicity. Notably, the sponge showed excellent antibacterial properties against E. coli and S. aureus and the wound closure rate treated by CH/CS/AgNPs sponge reached to 76.5% after 11 days. This work proposes new ideas for the study of antibacterial hemostatic materials by introducing agricultural waste into medical hemostatic field.

Biobased and Eco-Compatible Beauty Films Coated with Chitin Nanofibrils, Nanolignin and Vitamin E

A stable water-based suspension containing chitin nanofibrils (CN), chitin nanofibrils complexed with nanolignin and the latter containing Vitamin E was prepared starting from CN nanosuspension and nanostructured powders. The water-based coating was deposited by a spray technique on three different renewable and biodegradable films consisting of biodegradable polyesters and starch to prepare possible beauty mask prototypes. After drying, the films were extracted with water to control their potential release on the wet skin and different amounts of released materials were obtained. The results were discussed considering the composition and morphology of the adopted substrates and their interactions with the coating. The eco-compatibility of these films is related to the absence of preservatives and their easy biodegradability in several environmental conditions, decreasing their burden on solid waste management with respect to fossil-based versions.

Smart and Sustainable Hair Products Based on Chitin-Derived Compounds

According to previous research studies, consumers worldwide are searching for new natural-oriented hair products that are both skin and environmentally friendly. Worldwide waste and air pollution, with the consequent environmental disasters, represent the greatest risk to human health and economy, further increased by the COVID-19 pandemic. Among others, non-biodegradable molecules are present in hair products (fossil-based additives, surfactants, etc.) and macromolecules (plastics). Plastics waste is considered the most serious problem, representing a forecast amount of 460 million tons per year by 2030, 12% of which is reused or recycled. Most plastics consumed, therefore, go to landfills and incineration, also if their recycling is considered an important driver of industrial profitability. Thus, the use of biopolymers represents an interesting alternative to produce biodegradable goods and tissues. After an introduction to the worldwide waste problem and the hair structure, the present review proposes the possibility to make biodegradable tissues that, realized by chitin nanofibrils and nano-lignin as natural polymers, may be used to produce an innovative and smart cosmetic hairline. Chitin-derived compounds are considered interesting polymers to produce non-woven tissues able to repair the hair damages provoked by the aggressiveness of both the environment and some aggressive cosmetic treatments, such as setting, bleaching, permanent waving, and oxidative coloring. The possible activity, that positively charged polymers such as chitin could have, has been speculated, interfering with the constitution and organization of the hair fibrils’ structure, which is negatively charged. The possibility of selecting biopolymers for their packaging is also discussed. Moreover, the use of these biopolymers, obtained from forestry-agro-food waste, may be of help to safeguard the further consumption of natural raw materials, necessary for future generations, also maintaining the earth’s biodiversity.

Influence of surface morphology of chitosan films modified by chitin nanofibrils on their biological properties

The paper is devoted to the study of influence of chitin nanofibrils on the structure, surface morphology, mechanical properties, and electrical conductivity of chitosan-based composite films intended for use in biomedical technologies. It was demonstrated that the optimal concentration of chitin nanofibrils in the composite film is 5 wt.%. For the films of this composition, we observed orientation of structural elements on film surface, enhanced mechanical properties as well as an increase in both specific conductivity and proliferative activity of skin fibroblasts on film surface. These results are related to the appearance of oriented structure in nanocomposites and to self-organization of chitosan macromolecules on the surface of chitin nanofibrils. It was revealed that increase in surface energy and surface hydrophilicity did not facilitate effective adhesion, viability and proliferative activity of cells during cultivation on the surface of composite films.

Acidic Ethanol/Water Casting Approach to Improve Chitin Nanofibril Dispersion and Properties of Propionylated Chitin Biocomposites

A fabrication process using acidic ethanol/water as a medium was developed to achieve homogenous dispersion of chitin nanofibrils (ChNFs) in a chitin propionate (CP) solution to form ChNF-reinforced CP nanocomposites. CP was prepared by propionylation of chitin to improve its dissolution in green organic solvents. ChNFs were extracted from chitin via partial alkali deacetylation in water. An acidified ethanol/water mixture as a medium was found to dissolve CP and disperse ChNF suspensions simultaneously, forming clear and stable formulations. The degree of ChNF dispersion and compatibility between ChNF and CP in the acidified ethanol/water mixture yielded transparent ChNF-reinforced CP nanocomposites with a moderate UV-blocking capability of up to 76%. The tensile strength and modulus of 15% ChNF-filled nanocomposites were enhanced by 66 and 97%, respectively, when compared to the neat films. In addition, the maximum degradation temperature was increased by 40 °C. The increase in storage modulus was more pronounced above the glass transition temperature. These results demonstrated that ChNFs had substantial reinforcing effects on the cast CP nanocomposites.

Structural information of biopolymer nanofibrils by infrared nanospectroscopy

Biopolymer nanofibrils, such as chitin and silk nanofibrils, are abundant and critical structural components in nature and materials engineering. However, characterizing these nanofibrils at single fibrillar scale is still a challenging task. Herein, infrared nanospectroscopy (nanoIR), a technique that combines the advances of both atomic force microscopy and infrared spectroscopy, was applied to detect the chemical and structural information of single chitin and silk nanofibrils. The results of this study reveal that nanoIR is a powerful approach to identify the single biopolymer nanofibrils with spatial resolution reaching up to ~10 nm. In addition, for silk nanofibrils, the results support that nanoIR can be used to analyze the relative content of each secondary structure by deconvolution, because the content of each secondary structure is consistent with the results obtained from the deconvolution of the traditional infrared spectrum. However, the prerequisite for this semi-quantitative analysis is the use of high signal-to-noise ratio spectra, and characteristic peak positions of each secondary structure in nanoIR spectra were predetermined.

Hydroxyapatite formation with the interface of chitin and chitosan

Hydroxyapatite (HA) film atop artificial implants surface can provide bioactive, osteoconductive and bone-similar interface. Traditional technique utilizes collagen coating to induce HA mineralization via charged functional groups. However, collagen loss as aging might lead to unstable interface. In this study, we presume that chitin (CH) with acetamide group chelates calcium ion and chitosan (CS) with amine group chelates phosphate ion, providing an ambiance for the HA crystallite formation. The presumption is evidenced by molar conductivity experiments. Besides, the hydrogen bonds of CH and electrostatic repulsion force of CS render different molecular architecture for the tunnel-connected structure. Furthermore, it forms porous morphology after HA mineralization evidenced by SEM images. Interestingly, mixing CH and CS provides the interface for Ca2+/PO43- capturing, rendering the formation of micro-crystallite with the 1.69/1.7 for the ratio of calcium to phosphate, being evidenced by EDX and AES experiments. Moreover, crystallinity index is calculated with XRD and FTIR spectra that CH–CS–HA possesses the highest crystallite to amorphous ratio. The HA film also shows good biocompatibility through L929 MTT test with 100% cell viability for the potential bio-applications. By the tapping-mode of AFM, the Young's modulus of CH–CS–HA surface is estimated to be 2.04 GPa near that of native bone.

Composites Based on Chitin Nanoparticles and Biodegradable Polymers for Medical Use: Preparation and Properties

Chitin nanocrystals and nanofibrils possess attractive mechanical and biological properties, which makes them promising for application in different fields. This review discusses the application of chitin nanoparticles as a filler in composites based on biodegradable polymers. Different polymer matrices are considered: synthetic, semisynthetic, and natural (proteins and polysaccharides). Since chitin nanoparticles and nanofibrils possess a high aspect ratio and high Young’s modulus, the main attention is given to the mechanical properties of the composites. Due to the high bioactivity of chitin, composite materials based on it feature interesting biological properties.

Electrodynamic assisted self-assembled fibrous hydrogel microcapsules: a novel 3D in vitro platform for assessment of nanoparticle toxicity.

Nanoparticle (NP) toxicity assessment is a critical step in assessing the health impacts of NP exposure to both consumers and occupational workers. In vitro assessment models comprising cells cultured in a two-dimensional tissue culture plate (2D-TCP) are an efficient and cost-effective choice for estimating the safety risks of NPs. However, in vitro culture of cells in 2D-TCPs distorts cell–integrin and cell–cell interactions and is not able to replicate an in vivo phenotype. Three-dimensional (3D) in vitro platforms provide a unique alternative to bridge the gap between traditional 2D in vitro and in vivo models. In this study, novel microcapsules of alginate hydrogel incorporated with natural polymeric nanofibers (chitin nanofibrils) and synthetic polymeric nanofibers poly(lactide-co-glycolide) are designed as a 3D in vitro platform. This study demonstrates for the first time that electrodynamic assisted self-assembled fibrous 3D hydrogel (3D-SAF hydrogel) microcapsules with a size in the range of 300–500 μm in diameter with a Young's modulus of 12.7–42 kPa can be obtained by varying the amount of nanofibers in the hydrogel precursor solutions. The 3D-SAF microcapsules were found to mimic the in vivo cellular microenvironment for cells to grow, as evaluated using A549 cells. Higher cellular spreading and prolonged proliferation of A549 cells were observed in 3D-SAF microcapsules compared to control microcapsules without the nanofibers. The 3D-SAF microcapsule integrated well plate was used to assess the toxicity of model NPs, e.g., Al2O3 and ZnO. The toxicity levels of the model NPs were found to be dependent on the chemistry of the NPs and their physical agglomeration in the test media. Our results demonstrate that 3D-SAF microcapsules with an in vivo mimicking microenvironment can be developed as a physiologically relevant platform for high-throughput toxicity screening of NPs or pharmaceutical drugs.

The role of low molecular weight organic acids in release kinetics of zinc and cadmium in polluted calcareous soil in the presence of fish scales derivatives

ABSTRACT Immobilisation is an effective technique in the remediation of heavy metals polluted soils. A laboratory experiment was conducted to clarify the kinetics of Zn and Cd release using citric, oxalic, acetic and tartaric acids and to evaluate the effectiveness of fish scale powder (FSP), chitin (CTN) and chitosan (CTS) in the immobilisation of these metals in a calcareous soil exposed to high levels of Zn and Cd. Characterisation of Fourier-transform infrared spectroscopy (FTIR) revealed the presence of amines, amides, alkenes and phosphate esters in fish scale and its derivatives. Citric acid released Zn and Cd much higher than tartaric, acetic and oxalic acids. Addition of fish scales derivatives drastically decreased the cumulative release of Zn and Cd in the order of CTS> CTN> FSP. Zn release data well fitted to pseudo-second-order model only in the presence of citric and tartaric acid and to Elovich model in the presence of acetic and oxalic acids. Cd release data were mostly fitted to pseudo-second-order model followed by Elovich model. Results of the present study demonstrate the high capability of citric acid in releasing metals, and high effectiveness of fish scales derivatives especially chitosan in immobilising Cd and Zn in polluted soils.

Cinnamon Cassia Oil Emulsions Stabilized by Chitin Nanofibrils: Physicochemical Properties and Antibacterial Activities.

Nowadays consumers are increasingly demanding food with fewer synthetic preservatives, which makes antimicrobial essential oils (EOs) from plants promising alternatives. In this work, surfactant-free emulsions were successfully fabricated from Cinnamon cassia oil (C. cassia oil) with partially deacetylated chitin nanofiber (ChNF) adopted as a Pickering stabilizer. The storage stability and microstructures of the emulsions with different concentrations of ChNF were studied in detail. As ChNF concentration increased, the emulsion droplet size decreased while the emulsion stability increased with stable periods as long as 90 days. This could be attributed to the Pickering stabilization realized by irreversible adsorption of the ChNF at the oil-water interface (revealed by fluorescent microscopy) and subsequent formation of an interdroplet ChNF network in the continuous phase, which was further strengthened in the presence of the aldehyde moiety in the C. cassia oil (verified by FTIR spectra). The rheological data and SEM images provided further evidence for network formation in the emulsions with increased ChNF concentration. Furthermore, the antimicrobial activity of the emulsion against Escherichia coli and the release patterns of EOs from emulsions were also investigated. The emulsions showed prolonged antibacterial activities but enhanced diffusion efficiency with the introduction of ChNF, which turned out to be a good encapsulation system for the controlled release of EOs. This work evidences the promising advantages of ChNF-stabilized Pickering emulsions as a facile EOs delivery system for application in food preservation and related fields.

Development of food-grade Pickering emulsions stabilized by a mixture of cellulose nanofibrils and nanochitin

There is increasing interest in the food industry to develop plant-based emulsifiers for sustainability, ethical, and health reasons. In this study, we showed that stable Pickering emulsions could be fabricated using either cellulose or and chitin nanofibrils, as well as their physical mixtures. These emulsions were highly stable to droplet coalescence during storage, which we attributed to the ability of the nanofibers to adsorb to the oil droplet surfaces and form a thick particulate layer that protected them from coalescence. Moreover, the nanofibers formed a 3D-network in the aqueous phase that prevented the oil droplets from moving, thereby improving their creaming stability. We identified the optimum nanoparticle concentration and nanochitin-to-nanocellulose ratio required to formulate these emulsions. These nanofibers may be useful as edible particle-based emulsifiers for forming more sustainable plant-based food emulsions.

Electrosprayed Chitin Nanofibril/Electrospun Polyhydroxyalkanoate Fiber Mesh as Functional Nonwoven for Skin Application.

Polyhydroxyalkanoates (PHAs) are a family of bio-based polyesters that have found different biomedical applications. Chitin and lignin, byproducts of fishery and plant biomass, show antimicrobial and anti-inflammatory activity on the nanoscale. Due to their polarities, chitin nanofibril (CN) and nanolignin (NL) can be assembled into micro-complexes, which can be loaded with bioactive factors, such as the glycyrrhetinic acid (GA) and CN-NL/GA (CLA) complexes, and can be used to decorate polymer surfaces. This study aims to develop completely bio-based and bioactive meshes intended for wound healing. Poly(3-hydroxybutyrate)/Poly(3-hydroxyoctanoate-co-3-hydroxydecanoate), P(3HB)/P(3HO-co-3HD) was used to produce films and fiber meshes, to be surface-modified via electrospraying of CN or CLA to reach a uniform distribution. P(3HB)/P(3HO-co-3HD) fibers with desirable size and morphology were successfully prepared and functionalized with CN and CLA using electrospinning and tested in vitro with human keratinocytes. The presence of CN and CLA improved the indirect antimicrobial and anti-inflammatory activity of the electrospun fiber meshes by downregulating the expression of the most important pro-inflammatory cytokines and upregulating human defensin 2 expression. This natural and eco-sustainable mesh is promising in wound healing applications.

Fabrication of poly (1, 8-octanediol-co-Pluronic F127 citrate)/chitin nanofibril/bioactive glass (POFC/ChiNF/BG) porous scaffold via directional-freeze-casting

Abstract The citrate-based thermoset elastomer is a promising candidate for bone scaffold material, but the harsh curing condition made it difficult to fabricate porous structure. Recently, poly (1, 8-octanediol-co-Pluronic F127 citrate) (POFC) porous scaffold was creatively fabricated by chitin nanofibrils (ChiNFs) supported emulsion-freeze-casting. Thanks to the supporting role of ChiNFs, the lamellar pore structure formed by directional freeze-drying was maintained during the subsequent thermocuring. Herein, bioactive glass (BG) was introduced into the POFC porous scaffolds to improve bioactivity. It was found the complete replacement of ChiNF particles with BG particles could not form a stable porous structure; however, existing at least 15 wt% ChiNF could ensure the formation of lamellar pore, and the interlamellar distance increased with BG ratios. Thus, the BG granules did not contribute to the formation of pore structure like ChiNFs, however, they surely endowed the scaffolds with enhanced mechanical properties, improved osteogenesis bioactivity, better cytocompatibility as well as quick degradation rate. Reasonably adjusting BG ratios could balance the requirements of porous structure and bioactivity.

Preparation and Properties of Corn Starch/Chitin Composite Films Cross-Linked by Maleic Anhydride.

To improve the functional properties of starch-based films, chitin (CH) was prepared from shrimp shell powder and incorporated into corn starch (CS) matrix. Before blending, maleic anhydride (MA) was introduced as a cross-linker. Composite CS/MA-CH films were obtained by casting-evaporation approach. Mechanical property estimation showed that addition of 0–7 wt % MA-CH improved the tensile strength of starch films from 3.89 MPa to 9.32 MPa. Elongation at break of the films decreased with the addition of MA-CH, but the decrease was obviously reduced than previous studies. Morphology analysis revealed that MA-CH homogeneously dispersed in starch matrix and no cracks were found in the CS/MA-CH films. Incorporation of MA-CH decreased the water vapor permeability of starch films. The water uptake of the films was reduced when the dosage of MA-CH was below 5 wt %. Water contact angles of the starch films increased from 22° to 86° with 9 wt % MA-CH incorporation. Besides, the composite films showed better inhibition effect against Escherichia coli and Staphylococcus aureus than pure starch films.

Preparation of Nano/Submicron Ganoderma Tsugae and Its Stability

The preparation and stability of nano/submicrometer-sized Ganoderma tsugae (G. tsugae) was explored. The fruit body of G. tsugae was treated by homogenization and media-milling. Three sizes (0.8, 0.3, and 0.2 mm) of media were employed for consecutive milling. The final product was obtained by centrifugation (10,000 g, 10 min). Particle sizes were determined by using a laser-light particle size analyzer and further examined by using transmission electron microscopy. The removal of large particles resulted in better stability. After being stored at25°C for 21 days, the volume-average diameter of supernatant III increased from 0.105 to 0.137 μm. Freeze-drying resulted in particle aggregation and an increase in particle size. Twenty percent of the particles in the freeze-dried supernatant III were smaller than 100 nm, with an average diameter greater than 1 μm. Nevertheless, autoclaving did not result in severe instability of supernatant III. After being stored at 25°C for 12 months, about 40% of the particles were smaller than 100 nm, with an average diameter of 373 nm. In addition, the contents of bioactive compounds such as β-(1,3)-D-glucans, crude triterpenoids, total dietary fiber and chitin in media-milled products were much greater than those present in the hot-water extract.

Preparation and Study of Hemostatic Materials Based on Chitosan and Chitin Nanofibrils

The natural polymer chitin and its derivative chitosan are among the most promising polymers to create hemostatic materials. Composite fibers with different ratios of chitin nanofibrils were obtained by wet spinning. Study of the mechanical characteristics of composite fibers has shown that the introduction of a small amount of chitin nanofibrils, approximately 0.5 wt %, is accompanied by the strengthening of the fibers, while the use of high concentrations leads to an increase in the resistance of the fibers to the impacts of a wet environment. A nonwoven fabric obtained from the composite fibers has shown efficacy comparable to the commercial hemostatic agents Surgicel and Tachocomb. The assessment of the interaction of the developed materials in the body was carried out in in vivo experiments. It has been shown that chitosan fibers have a bioinert character. The formation of a dense connective tissue capsule around the implanted fiber was observed on the 91st day, which indicates a low rate of its resorption in the subfascia. A histological study of the interaction of the developed materials with the tissues of a living organism showed the presence of numerous giant multinucleated cells in the area of implantation.

Tough Nature-Inspired Helicoidal Composites with Printing-Induced Voids

Summary Exoskeletons of Odontodactylus japonicas, the “smasher-type” mantis shrimp, feature a raptorial appendage comprising a Bouligand architecture of chitin nanofibrils with newly observed voids or defects between the polysaccharide α-chitin and protein interfaces. Here, we use a continuous-fiber 3D printing technology to simulate such materials in carbon fiber-reinforced (helicoidal) composites, complete with the presence of voids due to imperfect printing. The specific impact energies of the 3D printed helicoidal composites are clearly superior and further enhanced by the presence of the voids. To explain the role of the Bouligand architecture, interlaminar stresses are computed and found to yield anti-delamination characteristics, and a theoretical model is derived to evaluate the optimal helicoidal architecture. Finite element modeling indicates that the voids tend to deform and coalesce on loading and appear to guide the fracture into the formation of an ideally twisted crack in the printed helicoidal composites, thereby contributing to the impact toughness.

Sustainable Micro and Nano Additives for Controlling the Migration of a Biobased Plasticizer from PLA-Based Flexible Films.

Plasticized poly(lactic acid) (PLA)/poly(butylene succinate) (PBS) blend-based films containing chitin nanofibrils (CN) and calcium carbonate were prepared by extrusion and compression molding. On the basis of previous studies, processability was controlled by the use of a few percent of a commercial acrylic copolymer acting as melt strength enhancer and calcium carbonate. Furthermore, acetyl n-tributyl citrate (ATBC), a renewable and biodegradable plasticizer (notoriously adopted in PLA based products) was added to facilitate not only the processability but also to increase the mechanical flexibility and toughness. However, during the storage of these films, a partial loss of plasticizer was observed. The consequence of this is not only correlated to the change of the mechanical properties making the films more rigid but also to the crystallization and development of surficial oiliness. The effect of the addition of calcium carbonate (nanometric and micrometric) and natural nanofibers (chitin nanofibrils) to reduce/control the plasticizer migration was investigated. The prediction of plasticizer migration from the films’ core to the external surface was carried out and the diffusion coefficients, obtained by regression of the experimental migration data plotted as the square root of time, were evaluated for different blends compositions. The results of the diffusion coefficients, obtained thanks to migration tests, showed that the CN can slow the plasticizer migration. However, the best result was achieved with micrometric calcium carbonate while nanometric calcium carbonate results were less effective due to favoring of some bio polyesters’ chain scission. The use of both micrometric calcium carbonate and CN was counterproductive due to the agglomeration phenomena that were observed.

Thermodynamics of interaction between water and the composite films based on chitosan and chitin nanofibrils

Interaction between water and composite films based on chitosan and chitin nanofibrils was studied. Isotherms of water vapor sorption by composite films were used to calculate partial values of entropy and enthalpy of sorbate; dependences of entropy and enthalpy on water sorption value were obtained. It was demonstrated that introducing chitin nanofibrils into chitosan matrix leads to decrease in sorption capacity of composite films. Apparently, this phenomenon is caused by formation of ordered structures consisting of chitosan macromolecules on the surface of chitin nanofibrils. The hypothesis was confirmed by calculations of thermodynamic parameters of the chitosan/chitin/water system. The calculations led to the conclusion that thermodynamically stable chitosan/chitin system is formed in composite films; in addition, it was revealed that the strongest chitosan-chitin interaction arises in the composite containing 1−5 wt.% of chitin nanofibrils. In this concentration range, Gibbs energy, entropy and enthalpy of mixing pass through a minimum; this result indicates that the highest affinity between chitosan and chitin exists when concentration of chitin nanofibrils varies from 1 to 5 wt.%.