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Different routes to turn chitin into stunning nano-objects
... 5 Its great availability through the crustacean shells (mainly shrimp, crab and lobster, prawn and krill), makes the wastes of the fishing industry to be the main source for chitin production. 6,7 Chitin, is considered a semicrystalline polymer-like nanofibrils. It is a high-molecular-weight linear polymer composed of Nacetyl-2-amino-2-deoxy-D -glucose units linked by β(14) bonds ( Fig. 1). ...
... To obtain chitin nanofillers, first, chitin needs to be extracted from the raw material; and then, the isolation of chitin nanofillers can be done. 6 Regarding that, up to date, there have been many studies on how to isolate chitin nanofillers by using chemical, mechanical, physical treatments or a combination of different approaches. 6,[21][22][23][24] The wide variety of chitin nanofillers that can be isolated in terms of size, shape, crystallinity, aspect ratio or morphology, depends on two factors such as: (i) the chitin source; or (ii) the isolation process. ...
... 6 Regarding that, up to date, there have been many studies on how to isolate chitin nanofillers by using chemical, mechanical, physical treatments or a combination of different approaches. 6,[21][22][23][24] The wide variety of chitin nanofillers that can be isolated in terms of size, shape, crystallinity, aspect ratio or morphology, depends on two factors such as: (i) the chitin source; or (ii) the isolation process. 6,8 The most common chitin nanofillers (altogether abbreviated here as nanochitin) are chitin nanocrystals (CHNC) and chitin nanofibers (CHNF). ...
Our regard to the use of chitin as a material has drastically changed since its discovery, 210 years ago. From an intractable material because of its insolubility in common solvents, it became one of the most important raw materials serving as a source of chitosan (its main derivative), and more recently, as source of nanometric forms: nanocrystals and nanofibers. Nanoscale chitin forms are remarkable high-value compounds for nanomaterials' development, due to their intrinsic biological and mechanical properties, as well as their potential as eco-friendly components to valorize the plentiful by-products of the seafood industry. Lately, these nanochitin forms have been widely used as nanofillers in polymer nanocomposites, and in particular, in natural biologically-active matrices for the development of biomaterials. The recent progresses achieved in the last two decades concerning the use of nanoscale chitin in biologically-active matrices for tissue engineering is highlighted in this review. First, an overview on the use of nanochitin in the different biomedical fields is presented and discussed. Then, the state-of-the-art regarding the development of biomaterials based on chitin nanocrystals or nanofibers is described in the context of the role of nanochitin in biologically-active matrices namely polysaccharides (chitin, chitosan, cellulose, hyaluronic acid, alginate), proteins (silk, collagen, gelatin) and others (lignin). Finally, major conclusions and perspectives on the use of nanochitin as an increasingly important raw material are described.
... This review summarizes developments in the extraction of chitin from crustacean shells, production of chitosan and nanochitin, and applications for each of these materials. prior reviews have delved extensively into extraction methods for chitin and related materials; some describe a single suite of methodologies, whether they be chemical or biological, and some approach the field as a whole [5,[10][11][12][13][14][15]. Other reviews have discussed work related to applications of these materials, including broad reviews providing surveys on a wide range of applications and more focused reviews describing specific fields, such as drug delivery, tissue engineering, and energetic applications [3,6,[14][15][16][17][18][19][20][21]. ...
... prior reviews have delved extensively into extraction methods for chitin and related materials; some describe a single suite of methodologies, whether they be chemical or biological, and some approach the field as a whole [5,[10][11][12][13][14][15]. Other reviews have discussed work related to applications of these materials, including broad reviews providing surveys on a wide range of applications and more focused reviews describing specific fields, such as drug delivery, tissue engineering, and energetic applications [3,6,[14][15][16][17][18][19][20][21]. The objective of this review is to corroborate information regarding both the extraction and application of chitin, chitosan, and nanochitin, including new developments since the publication of those prior review articles. ...
... Nanofibers and nanocrystals share a similar morphology; both are long, crystalline rods with high aspect ratios. Nanofibers differ from nanocrystals in length; nanocrystals are up to hundreds of nanometres long, while the length of nanofibers can extend into microns [15]. Nanoparticles describe nanostructures that lack the crystallinity and aspect ratios of the other morphologies due to differences in synthetic methods [14]. ...
Crustacean shells are a sustainable source of chitin. Extracting chitin from crustacean shells is ongoing research, much of which is devoted to devising a sustainable process that yields high-quality chitin with minimal waste. Chemical and biological methods have been used extensively for this purpose; more recently, methods based on ionic liquids and deep eutectic solvents have been explored. Extracted chitin can be converted into chitosan or nanochitin. Once chitin is obtained and modified into the desired form, it can be used in a wide array of applications, including as a filler material, in adsorbents, and as a component in biomaterials, among others. Describing the extraction of chitin, synthesis of chitosan and nanochitin, and applications of these materials is the aim of this review. The first section of this review summarizes and compares common chitin extraction methods, highlighting the benefits and shortcomings of each, followed by descriptions of methods to convert chitin into chitosan and nanochitin. The second section of this review discusses some of the wide range of applications of chitin and its derivatives.
... A general acid hydrolysis procedure was used to prepare chitin nanocrystals, as described in [16,20]; the effects of production conditions on nanocrystal properties are extensively reviewed in [18]. Crude chitin powder was hydrolyzed in 3 M HCl for 90 min at 90 • C, after which the reaction was stopped by cooling the mixture on ice. ...
... Irrespective of the modification method used, ChNC particles are rod-like, with an average length of~200 nm and diameter of~10 nm, and thus have an aspect ratio of~20. These dimensions are well within the ranges commonly found in literature, confirming successful chitin nanocrystal production [9,18,20]. In contrast to other esterification reactions where chloride intermediates were used [19,24], Steglich esterification did not affect the morphology or the size of the ChNC, thus confirming that Steglich esterification is rather mild. ...
... Irrespective of the modification method used, ChNC particles are rod-like, with an average length of ~200 nm and diameter of ~10 nm, and thus have an aspect ratio of ~20. These dimensions are well within the ranges commonly found in literature, confirming successful chitin nanocrystal production [9,18,20]. In contrast to other esterification reactions where chloride intermediates were used [19,24], Steglich esterification did not affect the morphology or the size of the ChNC, thus confirming that Steglich esterification is rather mild. ...
Bioplastics may solve environmental issues related to the current linear plastic economy, but they need improvement to be viable alternatives. To achieve this, we aimed to add chitin nanocrystals (ChNC) to polylactic acid (PLA), which is known to alter material properties while maintaining a fully bio-based character. However, ChNC are not particularly compatible with PLA, and surface modification with fatty acids was used to improve this. We used fatty acids that are different in carbon chain length (C4–C18) and degree of saturation (C18:2). We successfully used Steglich esterification and confirmed covalent attachment of fatty acids to the ChNC with FTIR and solid-state 13C NMR. The morphology of the ChNC remained intact after surface modification, as observed by TEM. ChNC modified with C4 and C8 showed higher degrees of substitution compared to fatty acids
with a longer aliphatic tail, while particles modified with the longest fatty acid showed the highest hydrophobicity. The addition of ChNC to the PLA matrix resulted in brown color formation that was reduced when using modified particles, leading to higher transparency, most probably as a result of better dispersibility of modified ChNC, as observed by SEM. In general, addition of ChNC
provided high UV protection to the base polymer material, which is an additional feature that can be created through the addition of ChNC, which is not at the expense of the barrier properties, or the mechanical strength.
... 14 As a kind of rod-like nanomaterial with high aspect ratio, chitin nanocrystal has been regarded as an ideal drug carrier due to its rich surface functional groups, high surface charge, excellent mechanical properties and good fluidity. 15 Its special rod-like structure makes it easier to enter cells and can increase the unit concentration of loading agents, which enhances the cell penetration of drugs. 16,17 Conjugating Cu 2+ onto the surface of chitin nanocrystals, the material properties of chitin nanocrystals can help Cu 2+ perform high-efficient antibacterial activity, which could not only induce plant resistance, but also has a high antibacterial effect and reduce the application amount of Cu 2+ in the field. ...
... It has been reported that chitin has antibacterial activity, and the higher the potential, the stronger the antibacterial activity. 15 Thus, it is assumed that the lack of obvious antibacterial activity of ChNC may be related to the significant reduction of potential after carboxylation. Figure 3(b) showed the cell survival rate of each treatment group in plate experiments. It could be seen that when the copper contents in ChNC@Cu and TC were the same (40 μg mL −1 ), the cell survival rate of ChNC@Cu was significantly lower than that of TC, indicating that ChNC@Cu had a more efficient antibacterial activity. ...
BACKGROUND
The application of chemical pesticides in control of plant bacterial disease may cause potential environmental pollution. Herein, based on the resistance‐inducing ability and the special rod‐like structure with high aspect ratio of bio‐derived chitin nanocrystals (ChNC), a new Cu composite rod‐like nanoparticle was fabricated (ChNC@Cu). The antibacterial activity of the composite nanoparticle was systematically studied, and its safety was evaluated.
RESULTS
TEM, FTIR, ICP and other characterization methods proved that ChNC@Cu is a nano rod‐like structure, with a Cu²⁺ loading capacity of 2.63%. In vitro experiments showed that the inhibition rate of ChNC@Cu to P. syringae pv. tabaci was more than 95% when the copper content was 41.6 μg mL⁻¹. In vivo experiments showed that ChNC@Cu had a good protective effect on P. syringae pv. tabaci of tobacco. In addition, ChNC@Cu exhibited stronger antibacterial activity than Thiodiazole copper (TC) at the same copper content. The study on the antibacterial mechanism of ChNC@Cu proved that ChNC@Cu caused bacterial death by destroying the bacterial cell membrane structure and damaging the DNA bacteria. And ChNC@Cu is highly safe for plants and can promote seed germination and plant growth.
CONCLUSION
The special rod‐like structure of ChNC can enrich Cu²⁺ to form ChNC@Cu. ChNC@Cu has a good protective effect on bacterial infection of tobacco, and achieves a great antibacterial activity at low Cu²⁺ concentration, which indicated that ChNC@Cu has induced resistance and antibacterial effect. As a novel green nanofungicide, ChNC@Cu has high potential application value in control of agricultural bacterial diseases. © 2023 Society of Chemical Industry.
... Chitin and its derivate chitosan are biocompatible, biodegradable, ecologically safe, have low toxicity, and show antioxidant and antimicrobial activities [1][2][3][4]. Consequently, these natural amino polysaccharides are often considered as being the perfect building blocks for a wide variety of products; a few examples are wound-dressing materials [5,6], clarification agents for the food industry [7,8], and fillers for rubbers and thermoplastics [9][10][11][12], in addition to many others [13,14]. ...
... In this paper, we take this method one step further and use it to characterize chitin nanocrystals, which are derived after the acid hydrolysis of crude chitin powder [10,14,25]. These nanoparticles have the potential to be applied widely, e.g., as fillers for thermoplastic polymers, and, more generally, for nano-composites [10,12,26,27]. ...
Chitin and its derivate chitosan have versatile properties and have been used in various applications. One key parameter determining the functionality of chitin-based materials is the degree of acetylation (DA). For DA determination, NMR and FTIR spectroscopy are often considered to be the gold standard, but these techniques may not always be available and are rather time-consuming and costly. The first derivative UV method has been suggested, although accurate measurements can be challenging for materials with high degrees of acetylation, due to hydroxymethylfurfural (HMF) formation and other side reactions occurring. In this paper, we re-evaluated the first derivate UV method for chitin and chitosan powder, chitin nanocrystals, and deacetylated chitin nanocrystals. Our results showed that the first derivative UV method is capable of measuring DA with high accuracy (>0.9), leading to values comparable to those obtained by 1H NMR, 13C NMR, and FTIR. Moreover, by-product formation could either be suppressed by selecting the proper experimental conditions, or be compensated. For chitin nanocrystals, DA calculation deviations up to 20% due to by-product formation can be avoided with the correction that we propose. We conclude that the first derivative UV method is an accessible method for DA quantification, provided that sample solubility is warranted.
... These effects play combined roles in ChNF assembly, interfibrillar H-bonding, and nonspecific interactions generated upon drying, endowing redispersibility. 474 For TEMPO-ChNF, while no significant effect of salt type was noted, given weak interactions between anionic nanofibers and monovalent counterions (Na + and NH 4 + ), the properties of aqueous dispersions reconstituted from dried TEMPO-ChNF were tunable. A TEMPO-ChNF suspension at 0.7% concentration displayed low viscosity, while a highly viscous, gel-like system occurred at 3.0% (Figure 27b2). ...
... Considering the morphology of nanochitin and its relatively large aspect ratio, one can expect that self-entangled or aggregated nanostructures can be formed by simply concentrating or drying the precursor suspensions. 196,474 Thus, nanochitin is suitable as a building block for creating films. 18,549,550 As such, structural nanochitin composites have been reported with biobased or synthetic polymers. ...
Chitin, a fascinating biopolymer found in living organisms, fulfills current demands of availability, sustainability, biocompatibility, biodegradability, functionality, and renewability. A feature of chitin is its ability to structure into hierarchical assemblies, spanning the nano- and macroscales, imparting toughness and resistance (chemical, biological, among others) to multicomponent materials as well as adding adaptability, tunability, and versatility. Retaining the inherent structural characteristics of chitin and its colloidal features in dispersed media has been central to its use, considering it as a building block for the construction of emerging materials. Top-down chitin designs have been reported and differentiate from the traditional molecular-level, bottom-up synthesis and assembly for material development. Such topics are the focus of this Review, which also covers the origins and biological characteristics of chitin and their influence on the morphological and physical-chemical properties. We discuss recent achievements in the isolation, deconstruction, and fractionation of chitin nanostructures of varying axial aspects (nanofibrils and nanorods) along with methods for their modification and assembly into functional materials. We highlight the role of nanochitin in its native architecture and as a component of materials subjected to multiscale interactions, leading to highly dynamic and functional structures. We introduce the most recent advances in the applications of nanochitin-derived materials and industrialization efforts, following green manufacturing principles. Finally, we offer a critical perspective about the adoption of nanochitin in the context of advanced, sustainable materials.
... After that, Tempo (0.1 mmol/10 g chitin) and sodium bromide (1 mmol/g chitin) were added to the dispersion. The oxidation of chitin by 2, 2, 6, 6-tetramethylpiperidine-1-oxyl (TEMPO) was initiated by adding a sodium hypochlorite solution (1-10 mmol/g chitin) 14,22 . Dispersion titration was conducted at room temperature by adding NaOH (0.5 M) solution continuously until the pH reached 10. ...
This study examined the impact of acid hydrolysis, tempo oxidation, and mechanical grinding on the physical, thermal, and structural properties of α-chitin nanocrystals and nanofibers. The manufacturing methods could influence the diameter, functional groups, and crystal patterns of the resulting nanoparticles. Analysis of the DLS results revealed that the size of acidic nanocrystals were smaller and showed improved dispersibility. The XRD patterns indicated that the chemical and mechanical treatments did not alter the crystalline arrangement of the α-chitin. FT-IR spectra analysis revealed that the chemical and mechanical methods did not affect the functional groups of the nanoparticles. DSC results showed that the nanoparticles had good thermal stability up to 400 °C, and it was found that the nanofibers had better thermal resistance due to their longer length. In the FE-SEM images, the nanoparticles were observed as fiber mats with a length of more than 100 nm. It was also found that the diameter of the nanoparticles was less than 100 nm.
... In the second step, the hydrolysis of glycosidic bonds releases nanochitin particles from the "bulk" chitin [36][37][38][39]. Hydrochloric acid [36,37,39,40], sulfuric acid [41,42], 2,2,6,6tetramethylpiperidine-1-oxyl radical (TEMPO)-mediated oxidation [43][44][45], periodatemediated oxidation [46], ammonium persulfate-mediated oxidation [47], and Deep Eutectic Solvent systems [48] have been proposed for hydrolysis. For the overall 'traditional' process of obtaining chitin nanowhiskers, 74.6% of CO 2 footprint (677 kg CO 2 equiv.) ...
Nanochitin, especially in the form of chitin nanowhiskers (ChNWs), represents a significant advance in biopolymer technology due to its high specific surface area, superior tensile strength, and excellent thermal stability. Derived from crustacean waste, which contains 15–40% of chitin, these materials provide a sustainable option that diverts waste from landfills and contributes to environmental conservation. Traditional methods of isolating nanochitin are energy-intensive and generate substantial waste. This study introduces a more sustainable method using inexpensive ionic liquids (ILs) such as [Hmim][HSO4] and [HN222][HSO4], which bypass the costly and destructive steps of traditional procedures. This study also identified the byproduct in IL-mediated chitin hydrolysis reaction as calcium sulfate dihydrate and presented a solution to circumvent the byproduct formation. The effectiveness of the [HN222][HSO4] IL in producing ChNWs from both purified chitin and crustacean biomass was assessed, showing a high yield and maintaining the purity and structural integrity of chitin, thereby demonstrating a significant reduction in the environmental footprint of ChNW production.
... Shrimp, crab, and lobster shells are being used to remove CT on an industrial or semiindustrial scale. The shellfish industry processes a wide variety of by-products in abundance [26]. ...
Recently marine-based biodegradable polymers received a key interest from researchers. Marine biopolymers are the key sources of naturally derived biodegradable polymers. There are many biopolymers that originate from fish, mollusks, seaweed, or microbes living in the marine system. Actually, the waste produced from marine-based foods is the key source of varieties of biopolymers. The extraction and purification of marine food waste after following chemical and biological processing produce many biopolymers. Both polysaccharide- and protein-based biopolymers can be produced from marine resources. The extracted biopolymers have many applications in the food and biomedical field. In this work, food processing and packaging applications of various types of marine biopolymers are briefly discussed.
... Chitin, a naturally abundant polysaccharide, consists of β-(1→4)-linked 2-amino-2-deoxy-D-glucosamine and is typically obtained from crustacean shells and fungi [36][37][38][39][40][41]. Nanochitins combine natural Chitin's desirable properties, such as biocompatibility, chemical stability, biodegradability, nontoxicity, and antibacterial activity [42], with the advantages of nanoscale materials, such as low density, surface reactivity, and high surface area. ...
The presence of high permeability zones causes the injected fluid/gas to bypass the low permeability pores, initiating an early breakthrough. One of the most influential and promising methods to control fluid bypass is fluid diversion using an emulsion/chemical agent placed at the highly permeable zone, which eventually diverts the injected fluids to a less permeable region. Chitin Nanocrystal (ChiNCs), a naturally abundant nanomaterial with high oil-water interfacial adsorption, has attracted significant interest as an emulsion stabilizer in various applications. Unlike traditional surfactants, ChiNCs offer a sustainable alternative by stabilizing the emulsion, providing long-term stability and enhanced viscoelasticity. This study presents a novel, eco-friendly solution by exploring ChiNCs as pickering emulsions stabilizers for conformance control in porous media. The ChiNCs were prepared through acid hydrolysis of chitin powder derived from crab shells. ChiNCs and their emulsions were analysed using Transmission Electron Microscopy (TEM), Dynamic Light Scattering (DLS), Zeta (ζ)-Potential, Cross-Polarized Microscopy (CPM), and rheometer. The presence of ChiNCs in the emulsion resulted in shear-thinning behaviour, making it suitable for conformance control. Core-flood experiment results confirmed the effectiveness of ChiNCs-stabilized emulsions for permeability reduction. Pressure drops and permeability reductions increased with larger emulsion slug sizes, indicating successful pore plugging and improved fluid diversion. The highest-permeability reduction with 85.6% were obtained with 0.7 pore volume (PV) of emulsion injection for a short time. In contrast, injecting 0.5 PV of the emulsion led to a significant and sustained permeability reduction of 80.8%. To the best of the authors' knowledge, this is the first application of chitin nanocrystals in fluid diversion and conformance control. The ζ-potential over +20 mV within the pH range 3–6 was sufficient to achieve the highest colloidal stability via electrostatic effect and good ChiNCs suspension transparency. The microstructure observed under the CPM correlates with the rheological behavior, showing that the ChiNCs provide a significant steric barrier to coalescence, thus enhancing the emulsion's resistance to flow and deformation.
... Nanochitin has the advantages of high longitudinal elastic modulus (more than 150 GPa in theory), high aspect ratio, and high specific surface area, and it is easy to obtain self-entangled or aggregated nanostructure by simply concentrating or drying nanochitin suspension. 86,87 Therefore, nanochitin can be prepared into high-performance films by suspension casting or drying. Fan et al. used four different types of nanochitin (TEMPO-oxidized a-ChNCs, partially deacetylated a-ChNCs/a-ChNFs mixture, HCl hydrolysis a-ChNCs and b-ChNFs) to prepare four films by suspension casting, which all had good transmittance and mechanical strength. ...
Chitin is an abundant and renewable non-wood biopolymer. Nanochitin is formed by the assembly of chitin molecules, which has the advantages of large tensile strength, high specific surface area, and biodegradability, so it has been widely used. However, the traditional methods of preparing nanochitin have many drawbacks. As the new generation of green solvents, deep eutectic solvents (DESs) have been successfully applied in the fields of chitin dissolution, extraction, and nanochitin preparation. In this review, the relevant knowledge of chitin, nanochitin, and DESs was first introduced. Then, the application status of DESs in the fields of chitin was summarized, with a focus on the preparation of nanochitin using DESs. In conclusion, this review provided a comprehensive analysis of the published literature and proposed insights and development trends in the field of preparation of nanochitin using DESs, aiming to provide guidance and assistance for future researchers.
... Materials placed in the natural category were all identified as chitin, found in the exoskeletons of insects, fungi, invertebrates, and fish (Elieh-Ali-Komi and Hamblin, 2016). However, upon further investigation, chitin is also used as a biopolymer with or without other materials such as silk, alginate, poly-lactic acid or collagen (Salaberria et al., 2015). Chitin appears to be used in wound management, drug delivery and cosmetics (Singh et al., 2017). ...
... Materials placed in the natural category were all identified as chitin, found in the exoskeletons of insects, fungi, invertebrates, and fish (Elieh-Ali-Komi and Hamblin, 2016). However, upon further investigation, chitin is also used as a biopolymer with or without other materials such as silk, alginate, poly-lactic acid or collagen (Salaberria et al., 2015). Chitin appears to be used in wound management, drug delivery and cosmetics (Singh et al., 2017). ...
... Materials placed in the natural category were all identified as chitin, found in the exoskeletons of insects, fungi, invertebrates, and fish (Elieh-Ali-Komi and Hamblin, 2016). However, upon further investigation, chitin is also used as a biopolymer with or without other materials such as silk, alginate, poly-lactic acid or collagen (Salaberria et al., 2015). Chitin appears to be used in wound management, drug delivery and cosmetics (Singh et al., 2017). ...
This study focused on quantifying the abundance of Microplastics within the surface water of the River Thames, UK. Ten sites in eight areas were sampled within the tidal Thames, starting from Teddington and ending at Southend-on-Sea, as well as Limehouse Harbour and two sites in the river Lea (River Thames tributary). Three litres of water were collected monthly at high tide from land-based structures from each site from May 2019 to May 2021. Samples underwent visual analysis for microplastics categorised based on type, colour and size. 1041 piece were tested using Fourier transform spectroscopy to identify chemical composition and polymer type. 6868 pieces of MP were found during sampling with an average MP of 12.27 pieces L-1 along the river Thames, 14.3 pieces L-1 in the River Lea and 46 pieces L-1 at Limehouse harbour. Results from this study show that microplastic abundance does not increase along the river.
... These nanoparticles combine the excellent properties of chitin with nano-impacted functionalities such as high aspect ratio, high surface area, and low density to form a stable and uniform dispersion in a system. Chitin nanomaterials were described as excellent materials with great potential to offer structural strength and improve mechanical properties in food systems, including food packaging applications [82]. ...
The application of chitin in food systems is limited by its insolubility in some common solvents and poor degradability. Hence, it is deacetylated to obtain chitosan, an industrially important derivative with excellent biological properties. Fungal-sourced chitosan is gaining prominence and industrial attraction because of its superior functional and biological properties, and vegan appeal. Further, the absence of such compounds as tropomyosin, myosin light chain, and arginine kinase, which are known to trigger allergic reactions, gives it an edge over marine-sourced chitosan in food and pharmaceutical applications. Mushrooms are macro-fungi with a significant content of chitin, with many authors reporting the highest content to be in the mushroom stalks. This indicates a great potential for the valorisation of a hitherto waste product. Hence, this review was written to provide a global summary of literature reports on the extraction and yield of chitin and chitosan from different fruiting parts of some species of mushroom, different methods used to quantify extracted chitin, as well as physicochemical properties of chitin and chitosan from some mushroom species are presented. Critical comparisons of reports on chitin and chitosan from mushrooms and other sources are made. This report concludes with an exposition of the potential application of mushroom-sourced chitosan for food packaging application. The reports from this review provide a very positive outlook regarding the use of mushrooms as a sustainable source of chitin and chitosan and the subsequent application of chitosan as a functional component in food packaging.
... The inherent antimicrobial activity is promising as new bacterial, fungal, and protozoal pathogens are on the rise, exhibiting resistance to the existing antibiotics in clinical use. A recent advent in the usage of chitin has been the fabrication of chitin nano-objects with a high surface area and low density, which include chitin nanocrystals (CHNCs), chitin nanofibers (CHNFs), and mats, by employing electrospinning and acid hydrolysis, thus overcoming limitations like its insolubility (Choy et al., 2020;Jung et al., 2018;Salaberria, Labidi, & Fernandes, 2015). Chitin nanofibrils show better antiinflammatory and antibacterial properties than does chitin (Milazzo et al., 2020). ...
... Extraction generally has two steps: Firstly, to purify chitin. It mainly contains alkali treatment or enzymatic digestion to remove proteins, acidic treatment to remove inorganic minerals, and have a bleaching treatment (CH3CH2OH) to reduce pigments and lipids [8,14]. In the next step, chitin is degraded to nano-chitin using acid hydrolysis, mechanical treatment, TEMPO oxidation, and partial deacetyl. ...
Chitin nano-materials derived from natural organisms are receiving much attention due to reduced fossil resources. In order to reduce carbon emissions and waste of valuable resources, nano-chitin materials manufacturing technology has been developed. Studies of the preparation and characterization of 3D printing functional nano-chitin materials can provide insights into desirable properties such as biocompatibility, high surface area. In this review, we compare and highlight the different methods for nano-chitin extraction from renewable resources and the conversion of the obtained nano-chitin into compound material with high 3D printing capabilities. Finally, the application of nano-chitin in the field of 3D printing is described with future prospects.
... It is emerging as a multifunctional product for the preparation of diverse advanced materials: papers [1], adsorbents for remediation of dye-contaminated wastes [2][3][4], reinforcing agent for composite biomaterials [5][6][7][8][9], biomedical devices [10][11][12], and biomimetic materials [13]. As a material, it has numerous advantageous qualities: biocompatibility and safety for human health [14,15], biodegradability [16,17], mechanical resistance [10,18,19], and suitability for chemical and physical modifications [20][21][22]. In particular, α-chitin is the predominant form of chitin found in the ocean, as a major constituent of the crustacean cuticle, among many others [23]. ...
Polybius henslowii, an abundant yet unexploited species of swimming crab, was investigated as a potential source of α-chitin and calcium lactate using deep eutectic solvents (DES) as extracting solvents. Choline chloride–malonic acid (CCMA) and choline chloride–lactic acid (CCLA) were used to obtain high purity α-chitin from ball-milled P. henslowii exoskeleton in 2 h at 120 °C, with yields of 12.05 ± 2.54% and 12.8 ± 1.54%, respectively. The physical and chemical characteristics of the obtained chitins were assessed using CHN elemental analysis, attenuated total reflectance–Fourier transform infrared spectroscopy, thermogravimetric analysis, and scanning electron microscopy. Furthermore, the CCLA solvent was reusable three times with little effect on the extract purity, and calcium lactate was produced at the end of the recycling cycles. The ensuing calcium lactate was also characterized in terms of chemical and physical properties. The obtained chitin is a promising raw material for downstream processing and the double valorization pathway with the obtention of calcium salts may increase the viability of a DES-based approach for the processing of mineralized substrates.
... Chitin contains highly crystalline regions and amorphous regions; the amorphous regions can be selectively removed via acid hydrolysis to produce rod-shaped chitin nanocrystals [15]. Researchers are exploring chitin nanocrystals for many applications, ranging from photonic applications to stabilizing Pickering emulsions [18][19][20][21]. Chitin nanocrystals have properties that make them appealing candidates for reinforcement of resin materials, considering the nanoparticles' small size, high surface area, high stiffness, low toxicity, and ease of chemical modification [22][23][24][25][26][27]. ...
Objectives
In this paper we propose embedding natural fillers, such as pristine and functionalized chitin nanocrystals, into resin adhesives to produce photopolymerizable dental filled adhesives with enhanced biocompatibility, hydrophobicity, mechanical resistance, and anti-bacterial properties.
Methods
Chitin nanocrystals (ChNC) were functionalized with decanoyl chloride and methacrylic anhydride to produce ChNC-C10 and ChNC-MA, respectively. These hydrophobically functionalized chitin nanocrystals were incorporated into a resin adhesive at concentrations of 0.5–3.0 wt% to assess the materials’ physical and mechanical properties through Fourier-transform infrared (FTIR) spectroscopy, solid-state NMR spectroscopy, X-ray diffraction (XRD), elemental analysis, scanning electron microscopy (SEM), thermogravimetric analysis (TGA), flexural strength, microhardness, and water sorption tests.
Results
The analytical techniques confirmed the successful preparation of chitin nanocrystals from commercial chitin powder derived from shrimp shells and the efficient hydrophobization of their surface. Electron microscope images indicated that the increased hydrophobicity of ChNC-C10 promotes the formation of layered structures throughout the resin adhesive, while ChNC-MA tends to form aggregates in the matrix. Adhesives filled with ChNC-C10 enhanced their flexural strength, microhardness, and thermal stability and decreased their water sorption and degree of conversion. Adhesives filled with ChNC-MA resulted in improvements in microhardness, in water sorption and degree of conversion, although they did not exhibit augmentation of their flexural strength and thermal stability.
Significance
In light of the improved physical and mechanical properties with respect to the control, resin adhesives filled with anti-bacterial chitin nanocrystals are promising new materials for dental applications, especially those filled with low/moderate amounts of ChNC-C10.
... The main structural unit of chitin is the filaments, which is a chitin fiber, are entrenched in protein matrix with diameters of 2.5 to 2.8 nm, which are firmly bonded with hydrogen bonds and in the form of crystalline and shapeless domains (( [33], [34]). Chitin nanowhiskers can be obtained by breaking the amorphous domains, which split the chitin crystallites ( [35], [36]). Chitosan is mostly used for its antimicrobial capability through the antimicrobial film synthesis through chitosan / alcohol combination, which function against food-borne pathogens, and has the potential to sustain pH, color and firmness of food samples ( [37], [38]). ...
Nanotechnology is used in food packaging to improve packaging properties such as gas leakage, heat and moisture resistance during packaging. Nanoparticles provide antimicrobial features through the development of innovative packaging systems to sense biochemical or microbial changes in food and detect the causes of food contamination and diseases to be used as a product monitoring tool for food safety and to avoid food fraud. Recently, nanoshells have been produced consisting of templates of polymers, where the dimensions of the pore holes are controlled, enabling them to prevent the exchange of moisture and gases with the external medium, which affects the distribution and use of coloring materials, flavoring materials, antioxidants, enzymes and anti-brown coloring materials. In packaging fresh food products such as meat, cheese, vegetables, fruits and others and preserving them even after opening the package by treating the surfaces of the outer packages with a thin transparent anti-oxidant layer.
... Moreover, this material is also inelastic, insoluble in water and common organic solvents, and displays a low chemical reactivity. Due to its insolubility, chitin was disregarded for a long time when compared to other polysaccharides [27,29]. Nowadays, chitin is extracted at a large scale, mostly from the abundant waste of shellfish (e.g., crab, shrimp, and lobster shells) processing industries. ...
Nowadays, chronic wounds are still a huge health problem with a high impact on the patients’ quality of life. In this way, the development of an ideal wound dressing is of utmost importance. To accomplish that, researchers have been using natural polymers to produce new types of dressings, that can activate/direct specific cellular responses, leading to an improved healing process. Among the natural polymers, chitin presents notable antibacterial and antiinflammatory properties that are crucial for enhancing the wound healing process. Moreover, chitosan, a deacetylated form of chitin, has been one of the most used biopolymers due to its straightforward processability into different forms, antimicrobial activity, and capacity to promote/accelerate the healing process. This chapter provides an overview of the properties exhibited by chitin and chitosan as well as examples of their application in the development of dressings aimed to improve the healing process.
... On the other hand, since chitin is difficult to dissolve in common solvent, there are few reports on the production of nanochitin by a bottom-up method. For example, Kadokawa et al. obtained nanochitin by dissolving chitin in an ionic liquid and then regenerating it [17][18][19]. ...
Most of the series of nanochitins have been produced by the break-down process. In this study, chitin nanoparticles were prepared by a bottom-up process. Chitin was treated with sodium hydroxide to obtain an alkaline chitin aqueous solution. The alkaline chitin was regenerated by neutralization and then vigorously stirred to obtain chitin nanoparticles. The average particle size of the chitin nanoparticles was 7 nm. The individual particles were stably dispersed in water. Chitin nanoparticles had lower crystallinity than the raw material chitin and the surface of the chitin nanoparticles regenerated in water were presumed to be hydrophilic. The low crystallinity and the high hydrophilicity of the surface contributed to the high dispersibility of the chitin nanoparticles in water. Chitin nanoparticles had higher heat resistance than the raw material chitin, suggesting a large change in the higher-order structure associated with dissolution and subsequent regeneration of chitin. Since chitin nanoparticles interact with each other less than chitin nanofibers produced by mechanical treatment, the viscosity of nanoparticles was smaller than that of nanofibers. Therefore, it can be prepared at a high concentration. In addition, the chitin nanoparticles can be easily redispersed in water after being concentrated by centrifugation.
... 4 Thanks to this organization, the exocuticle of crustaceans can reach a stiffness of 8.5−9.5 GPa. 4 Due to the abundance and renewability of chitin, various methods to isolate its nanocrystals have been developed, using water as main extractive medium. 5,6 Nanosized inherent properties such as high surface areas and reactivity, together with the mechanical performance and antibacterial activity, 7,8 have led to the exploitation of nano-chitin in pharmaceutical, 9 biomedical, 10,11 cosmetic, 12 and food-related 13 applications, among others. 14 Chitin nanocrystal (ChNC) potential can be exploited in different application categories. ...
In nature, chitin is organized in hierarchical structures composed of nanoscale building blocks that show outstanding mechanical and optical properties attractive for nanomaterial design. For applications that benefit from a maximized interface such as nanocomposites and Pickering emulsions, individualized chitin nanocrystals (ChNCs) are of interest. However, when extracted in water suspension, their individualization is affected by ChNC self-assembly, requiring a large amount of water (above 90%) for ChNC transport and stock, which limits their widespread use. To master their individualization upon drying and after regeneration, we herein report a waterborne topochemical one-pot acid hydrolysis/Fischer esterification to extract ChNCs from chitin and simultaneously decorate their surface with lactate or butyrate moieties. Controlled reaction conditions were designed to obtain nanocrystals of a comparable aspect ratio of about 30 and a degree of modification of about 30% of the ChNC surface, under the rationale to assess the only effect of the topochemistry on ChNC supramolecular organization. The rheological analysis coupled with polarized light imaging shows how the nematic structuring is hindered by both surface ester moieties. The increased viscosity and elasticity of the modified ChNC colloids indicate a gel-like phase, where typical ChNC clusters of liquid crystalline phases are disrupted. Pickering emulsions have been prepared from lyophilized nanocrystals as a proof of concept. Our results demonstrate that only the emulsions stabilized by the modified ChNCs have excellent stability over time, highlighting that their individualization can be regenerated from the dry state.
... In particular, chitin nanocrystals (ChNCs) have shown great potential as sustainable and bioactive nanomaterials in many uses. ChNCs are defined as nano-rod-shaped structures that are highly crystalline (even more than 80%), with a wide aspect ratio between 5 and 20 nm in width and hundreds of nm in length, depending on the source and treatment [7]. The source and treatment used during their synthesis also influence the surface chemistry of the nanocrystals, mainly hydroxyl, amine, carboxyl, and acetamide, which provide improved dispersibility of ChNCs and facilitate surface functionalization. ...
Biobased nanomaterials have gained growing interest in recent years for the sustainable development of composite films and coatings, providing new opportunities and high-performance products. In particular, chitin and cellulose nanocrystals offer an attractive combination of properties, including a rod shape, dispersibility, outstanding surface properties, and mechanical and barrier properties, which make these nanomaterials excellent candidates for sustainable reinforcing materials. Until now, most of the research has been focused on cellulose nanomaterials; however, in the last few years, chitin nanocrystals (ChNCs) have gained more interest, especially for biomedical applications. Due to their biological properties, such as high biocompatibility, biodegradability, and antibacterial and antioxidant properties, as well as their superior adhesive properties and promotion of cell proliferation, chitin nanocrystals have emerged as valuable components of composite biomaterials and bioactive materials. This review attempts to provide an overview of the use of chitin nanocrystals for the development of bioactive composite films in biomedical and packaging systems.
Presently, the rapid depletion of resources and drastic climate change highlight the importance of sustainable development. In this case, nanochitin derived from chitin, the second most abundant renewable polymer in the world, possesses numerous advantages, including toughness, easy processability and biodegradability. Furthermore, it exhibits better dispersibility in various solvents and higher reactivity than chitin owing to its increased surface area to volume ratio. Additionally, it is the only natural polysaccharide that contains nitrogen. Therefore, it is valuable to further develop this innovative technology. This review summarizes the recent developments in nanochitin and specifically identifies sustainable strategies for its preparation. Additionally, the different biomass sources that can be exploited for the extraction of nanochitin are highlighted. More importantly, the life cycle assessment of nanochitin preparation is discussed, followed by its applications in advanced manufacturing and perspectives on the valorization of chitin waste.
Biopolymers derived from plants, animals, or microbes have gained attention due to their potential as ecologically beneficial alternatives for traditional synthetic polymers. These polymers have excellent bio-making potential and come from a number of wastes or bioresources, including food, animal, and agricultural wastes, as well as other sources such as starch and cellulose. Due to their biocompatibility, superior mechanical properties, and availability from renewable feedstock, biopolymers offer a feasible solution to the urgent worldwide problem of producing sustainable materials. However, a lack of knowledge about the attributes and processing behaviors of biopolymers poses a barrier to their growth. Due to their ability to provide real-time insights into the properties and applications (biomedical, food packaging, and so on) of biopolymers, analytical techniques can potentially accelerate advancement in this field. This study explores the recent advances in the most beneficial biopolymers, such as chitosan, cellulose, keratin, chitin, polylactic acid (PLA), starch, and collagen, along with their application areas. Moreover, it highlights the challenges and opportunities in the biopolymer industry, including cost, scalability, and innovation.
Widespread concerns over the impact of human activity on the environment have resulted in a desire to replace artificial functional materials with naturally derived alternatives. As such, polysaccharides are drawing increasing attention due to offering a renewable, biodegradable, and biocompatible feedstock for functional nanomaterials. In particular, nanocrystals of cellulose and chitin have emerged as versatile and sustainable building blocks for diverse applications, ranging from mechanical reinforcement to structural coloration. Much of this interest arises from the tendency of these colloidally stable nanoparticles to self-organize in water into a lyotropic cholesteric liquid crystal, which can be readily manipulated in terms of its periodicity, structure, and geometry. Importantly, this helicoidal ordering can be retained into the solid-state, offering an accessible route to complex nanostructured films, coatings, and particles. In this review, the process of forming iridescent, structurally colored films from suspensions of cellulose nanocrystals (CNCs) is summarized and the mechanisms underlying the chemical and physical phenomena at each stage in the process explored. Analogy is then drawn with chitin nanocrystals (ChNCs), allowing for key differences to be critically assessed and strategies toward structural coloration to be presented. Importantly, the progress toward translating this technology from academia to industry is summarized, with unresolved scientific and technical questions put forward as challenges to the community.
Nanotechnology is a rapidly expanding field of study because of its numerous dermal applications and benefits in dermal care. It also represents progress in research and development by enhancing product efficacy through the adoption of novel technologies. Nanotechnology is increasingly being used in dermal applications to avoid some of the problems associated with traditional treatments. Dermal applications are the segment of the consumer products market that is expanding the fastest, and their popularity has exploded in recent years. In addition to wrinkles, hyperpigmentation, photoaging, hair damage, and dandruff, nanofibers are now frequently used in dermal treatments for skincare, hair, lips, and nails. These innovative dermal applications using nanofibers provide improved skin penetration, higher stability, site-specific targeting, controlled and prolonged drug release, and high entrapment effectiveness. The outcome of dermal applications can be improved with nanofibers by modifying their structure, functionality, chemical and mechanical resistance, and additional attributes. The importance of biopolymers in processing nanofibers, nanofiber processing methods, an overview of dermal applications' significance, and dermal applications based on nanofibers will all be discussed in this review.
Chitin-based nanoparticles are polysaccharide materials that can be produced from a waste stream of the seafood industry: crustacean shells. These nanoparticles have received exponentially growing attention, especially in the field of medicine and agriculture owing to their renewable origin, biodegradability, facile modification, and functionality adjustment. Due to their exceptional mechanical strength and high surface area, chitin-based nanoparticles are ideal candidates for reinforcing biodegradable plastics to ultimately replace traditional plastics. This review discusses the preparation methods for chitin-based nanoparticles and their applications. Special focus is on biodegradable plastics for food packaging making use of the features that can be created by the chitin-based nanoparticles.
Current trends in food packaging systems are toward biodegradable polymer materials, especially the food biopolymer films made from polysaccharides and proteins, but they are limited by mechanical strength and barrier properties. Nano-chitin has great economic value as a highly efficient functional and reinforcing material. The combination of nano-chitin and food biopolymers offers good opportunities to prepare biodegradable packaging films with enhanced physicochemical and functional properties. This review aims to give the latest advances in nano-chitin preparation strategies and its uses in food biopolymer film reinforcement and applications. The first part systematically introduces various preparation methods for nano-chitin, including chitin nanofibers (ChNFs) and chitin nanocrystals (ChNCs). The nano-chitin reinforced biodegradable films based on food biopolymers, such as polysaccharides and proteins, are described in the second part. The last part provides an overview of the current applications of nano-chitin reinforced food biopolymer films in the food industry.
β-chitin, a promising biopolymer for the production of chitosan and biomaterials, is sourced from fishery by-products. Herein, β-chitin has been extracted using Deep Eutectic Solvents (DES) for the first time, only the α-polymorph having been extracted using these solvents until now. Six acid, neutral, and alkaline DES systems were trialed, with only the alkaline DES systems, in particular potassium carbonate: glycerol (KGLY) at 100 or 120 °C for 2 or 3 h, resulting in high-purity β-chitin. The ensuing β-chitin was characterized in terms of chemical and physical structure, morphology, crystallinity, and thermal properties. Under the best extraction conditions, using the DES KGLY system, the β-chitin samples were highly pure, presenting an acetylation degree between 77 and 88%, a high crystallinity between 88 and 91%, and a maximum degradation temperature of around 350 °C. Moreover, the solvent system was easily recyclable with consistent performance over 3 cycles of re-use. The extraction method is well-suited for the extraction of crystalline β-chitin and could be integrated into future works in the production process of chitosan.
Shrimp meat is consumed globally on a large scale, and their processing releases a large amount of shell waste. The major constituents of shrimp shells are chitin, proteins, calcium carbonate, and lipids. To extract chitin from the shrimp shell, it has to undergo deproteination (DP) to remove the proteins and demineralization (DM) to separate the minerals. Traditionally shrimp shell wastes were dried and directly added as a fertilizer to soil or added in animal feed or dumped in landfills. In recent years, shrimp shell wastes are valorized for producing chitin, chitosan, and other beneficial products like protein hydrolysates, carotenoids, lactic acid, etc. Industries producing chitin are employing chemicals like hydrochloric acid and sodium hydroxide for demineralization and deproteination, respectively, and the residual water is dumped into the water bodies. Considering environmentally friendly approaches, the usage of microorganisms has been tried out for chitin extraction from the shrimp shell. The recent review highlights the production of chitin using microorganisms and mentions other recent greener approaches in chitin production.
Biodegradable substitutes to the commonly practiced packaging materials are always in high demand. Active biopolymer film was obtained from soy-protein isolate (SPI) and the antibacterial properties were introduced by incorporating silver nanoparticles. Active bio-composite films incorporating silver nanoparticles (AgNP) are much sought after in the food packaging industry owing to their ability to extend the shelf life of fresh foods. But the toxicity of the ingredients used for preparation (mainly the reducing agents) and the poor stability limits their usage for the aforementioned application. Herein, to counter these limitations, we have adopted an environment-friendly method where carbon dot (CD) prepared from soy protein isolate was used to prepare AgNPs. AgNPs (1% wt.) and different concentrations of chitin nano whisker (CNW) (2–10% wt.) were added to soy protein isolate to fabricate nanocomposite films. The subsequent effect on the latter’s tensile property, moisture content, thermal property and morphological characteristics were noted. Here, for the first time, the steam explosion technique was used for the preparation of CNW which resulted in highly crystalline CNW with good antibacterial properties. It was observed that the mechanical strength and thermal stability of SPI film were significantly increased and the moisture content decreased with the addition of CNW and AgNP. The synergistic effect of AgNP and CNW imparted excellent antioxidant, antibacterial and antifungal properties to the SPI film thus enabling the SPI film to extend the shelf life of the food material that was packed using the same. Commercial production of such SPI films would revolutionize the food packing industry given its health benefits and its cost-effectiveness.
Fully bio-based poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) (PHB) blends plasticized with tributyrin (TB), and their nanocomposite based on chitin nanoparticles (ChNPs) was developed using melt mixing followed by a compression molding process. The combination of PHB and ChNPs had an impact on the crystallinity of the plasticized PLA matrix, thus improving its oxygen and carbon dioxide barrier properties as well as displaying a UV light-blocking effect. The addition of 2 wt% of ChNP induced an improvement on the initial thermal degradation temperature and the overall migration behavior of blends, which had been compromised by the presence of TB. All processed materials were fully disintegrated under composting conditions, suggesting their potential application as fully biodegradable packaging materials.
Procedures for chitin nanofibers extraction from mushroom significantly modify their structure and physicochemical properties, through disintegration and surface oxidation of glucan residue, as well as surface deacetylation of chitin. Here, four kinds of chitin-glucan nanofibers (CGNF) were isolated form Shiitake stipes via different alkali treatment conditions, wherein glucan content ranged from 6.4 % to 46.8 %. Observations with transmission electron microscopy showed that CGNFs possessed average widths with 5.1 ± 1.2 to 7.1 ± 1.5 nm. The glucan showed a negative effect on the crystal index and thermal stability of CGNFs. A strong positive correlation was observed between glucan residues and zeta potential value. The phenomenon about the increase of viscosity, yield stress and elastic modulus upon glucan decrease was discussed. Overall, the residual glucan offers fungi-derived chitin nanomaterials a diversity of material properties and tuning its content is a feasible approach for customize nano chitin fibers used in nutraceutical and food industry.
Faster wound healing is critical to restore homeostasis. Chronic wounds that fail to heal pose a challenge for health care professionals and may result in socioeconomic and psychological imbalances. Wound dressing materials could enhance wound healing dramatically. The choice of suitable material for dressing depends on type of wound and cause. Natural polymers boast the attributes that can aid in rapid wound healing. This chapter discusses properties and applications of various natural polymers used in wound dressings and skin substitutes. A concise list of commercially available wound healing products that were made using natural polymers or their derivatives is also provided.
Environmental pollution and global warming have propelled the research activities toward the substitution of toxic materials with environmentally acceptable components in various spheres. Lithium‐ion battery (LIB) is exorbitantly used in different electronic devices in the present era and thus generates huge toxic electronic waste, which has become a global concern. Different approaches have been put forward to replace the commonly used materials for the fabrication of LIBs with processed biomass. This review discusses the significance and application of different biomass for fabricating electrodes and binders for LIBs. The electrochemical properties of the developed LIBs have also been discussed in detail. In addition, the required improvements have been put forth, so that biomass can be extensively used in future LIB to reduce the amount of generated toxic electronic wastes. Application of biowaste for the synthesis of Li‐ion battery. Morphology of the synthesized materials. Electrochemical properties of the synthesized materials. Efficiency of the natural products as components in Li‐ion batteries. The environmental safety of the materials as LIB components Conversion of different biowastes to materials in lithium‐ion batteries.
Carbohydrate-based nanofibrils, including cellulose nanofibrils (CNFs) and chitin nanofibrils (ChNFs) are highly ordered architectures which are the basis of various biological components with hierarchical features, low-cost, biocompatibility, and biofunctionality. To preserve these exceptional structural topographies and to directly use these natural nanofibrils assembly, different approaches have been introduced to exfoliate these nanofibrils from their origin. In this review, we aim to summarize the recent progress on the isolation methods of CNFs and ChNFs and their relation to their physical and chemical properties. In addition, recent studies on their biomedical applications, focusing on tissue engineering, wound dressing, biomedical implants, drug delivery, and biosensors are emphasized. After short evaluation of the toxicity and immunogenicity of these nanofibrils, the outlooks and current challenges of CNFs and ChNFs-based constructs for biomedical applications are summarized. This study shows that CNFs and ChNFs-based constructs have significant potential for a widespread biomedical application in the future.
Chitin is an abundantly available polysaccharide and is the primary structural component of crustacean shells. Nanochitin can be made by extracting chitin from crustacean shell waste (CSW) by depolymerization and demineralization, then using various top-down and bottom-up approaches such as acid hydrolysis, ultrasonication, grinding, microwave irradiation, and electrospinning. Nanochitin finds wide application in the food industry due to its unique characteristics, including its small size, solubility, low density, high surface area, superior chemical reactivity, low toxicity, biodegradability, biocompatibility, antioxidant activity, antimicrobial properties, and excellent mechanical performance. In this paper, the recent advances in preparation methods of nanochitin from CSW are reviewed. Food applications such as nanochitin's ability to stabilize Pickering emulsions, as a reinforcing agent in food films, improving saltiness perception of food, inhibition of starch retrogradation, and lipid digestion are also discussed. This review will contribute to a deeper understanding of nanochitin's potential as a functional food ingredient.
Natural materials can inspire the design of functional structures and sustainable materials. Bacterial biofilms formed by polymicrobial cultures typically comprise a robust interwoven fibrous network made of proteins and exopolysaccharides, protecting the cells trapped inside against various environmental stressors. Inspired by these structures, we report an amyloid-polysaccharide composite matrix using the building block of Escherichia coli biofilms (CsgA) and chitin, the second most abundant polysaccharide. We chose these two substances to mimic the main components of biofilms and combine the toughness of polysaccharide fibers and the functionality of amyloid fusion proteins to produce a new functional hybrid material. Due to the chitin-binding domain and other functional tags, the chitin-amyloid composite matrix exhibited good molecular interaction and functionality, which formed a coating on the material surface and was made into a freestanding film. With the help of this composite coating, we adhered inorganic materials onto various material surfaces. The ability to interact with inorganic materials allows this new material to be applied to electronics and organic-inorganic interfaces, and the freestanding films provide an opportunity for fabricating intelligent materials or wearable electronic devices. Additionally, these biopolymer ingredients may offer a low-cost and environmentally-friendly bio-based alternative to industrial polymers or plastics in consumer products.
Deep eutectic solvents (DES) consist of a mixture of compounds, which when combined, present a melting point lower than that of each individual compound. They are an emerging class of alternative solvents notable for their versatility and green credentials. Moreover, they can be synthesized with renewable, non-toxic and biocompatible components and can be reused over several cycles. Over the past decade, they have been increasingly used to extract biopolymers and small molecules from marine biomass and to synthesize biomaterials from marine-origin compounds. Herein, a general overview of the use of DES for processing marine biomass is provided. First, the relevant properties of DES for processing marine biomass, and use as extraction media and as functional adjuvantsare described. Then, the current state of the art concerning the progress made on their use for processing crustacean, fish by-products and seaweeds for the extraction of polysaccharides, proteins, and pigments, as well as their use to create functional materials is explained. The issues concerning DES properties, extract purification, toxicity and biodegradation are also stated. Finally, the future perspectives of DES are discussed. Despite some presentedchallenges, DES are promising systems for the processing of marine biomass with high future potential.
With approximately 250,000 marine species, the ocean is a vast reservoir of biodiversity and an abundant biological resource of natural polymers. The wide variety, renewable nature, tunable physicochemical and structural behavior and appealing biological properties make these marine biopolymers particularly attractive to the scientific community and numerous industrial sectors. As raw materials, they offer novel opportunities for the development of bio-based materials in response to recent demands for biodegradable plastic materials to lower plastic pollution in marine ecosystems. The biodegradation of marine biopolymers and biopolymer-based materials depends on marine environmental conditions such as temperature, pH and in particular microbial population. Marine microorganisms producing biopolymer-degrading enzymes (i.e., hydrolases, lyases, oxidoreductases) are well studied, nonetheless the biodegradation processes of marine biopolymers-based materials in the marine/aquatic environment need further investigation. This review describes various biodegradation parameters and mechanisms of the degradation of marine biopolymers in the marine environment. It also puts emphasis on the marine microorganisms and the corresponding enzymes that catalyze the degradation of different marine biopolymers. Finally, it focuses on the few studies on biodegradation of emerging bio-based materials in aquatic ecosystems.
This study focuses on the use of pilot-scale produced polyhydroxy butyrate (PHB) biopolymer and chitin nanocrystals (ChNCs) in two different concentrated (1 and 5 wt.%) nanocomposites. The nanocomposites were compounded using a twin-screw extruder and calendered into sheets. The crystallization was studied using polarized optical microscopy and differential scanning calorimetry, the thermal properties were studied using thermogravimetric analysis, the viscosity was studied using a shear rheometer, the mechanical properties were studied using conventional tensile testing, and the morphology of the prepared material was studied using optical microscopy and scanning electron microscopy. The results showed that the addition of ChNCs significantly affected the crystallization of PHB, resulting in slower crystallization, lower overall crystallinity, and smaller crystal size. Furthermore, the addition of ChNCs resulted in increased viscosity in the final formulations. The calendering process resulted in slightly aligned sheets and the nanocomposites with 5 wt.% ChNCs evaluated along the machine direction showed the highest mechanical properties, the strength increased from 24 to 33 MPa, while the transversal direction with lower initial strength at 14 MPa was improved to 21 MPa.
A facile formic acid (15 M) hydrolysis method was established to prepare chitin nanofibrils that exhibited much longer fibril size (538–1000 nm) and higher yield (87–95%) than traditional hydrochloric acid hydrolyzed ones. Interestingly, these chitin nanofibrils can well be dispersed in water/TBA or water/ethanol binary solvents, which can contribute to the functionality of chitin nanofibrils in different way. On one hand, chitin nanofibril aerogels with tunable inter-structure were prepared via direct freeze-drying of chitin nanofibril/water/TBA dispersion with specific surface area could be promoted 69%. Meantime, re-dispersibility was realized, and the higher concentration of TBA used, the better re-disperse performance. On the other hand, due to the well disperse nature of chitin nanofibrils in water/ethanol (ethanol can reach 90%), they can be well mixed with zein. Whereby, the hydrophobic chitin nanofibril/zein composite aerogels were prepared and showed great potential in absorbing oil or organic spillage off water.
This paper provides an overview of the most up-to-date information available relating to chitin nanowhiskers. This paper presents aspects about chitin nanowhiskers, including methods of extraction and preparation, chemical modification and applications. Chitin nanowhiskers can be obtained by hydrochloric acid hydrolysis, TEMPO-mediated oxidation, partial deacetylation with NaOH by fibril surface cationization, ultrasonication, electrospinning, aqueous counter collision treatment, a simple grinding treatment and gelation with 1-allyl-3-methylimidazolium bromide. An introduction into the methods used to prepare chitin nanowhiskers is given. The chitin nanowhiskers applications are used mainly as reinforcing polymer nanocomposites, but also to prepare scaffolds, hydrogels and wound dressings, as adsorbents in industry, water purification, for protein immobilization, transformation of bacteria by exogenous genes, stabilization of oil-in-water emulsion and nematic gels, formation of CaCO 3 /chitin-whisker hybrids and as carbon precursors.
This chapter highlights some of the recent and important findings obtained from studies conducted on the synthesis, structure, physical state, modification, organization, and degradation of chitin in insect tissues, as well as the interplay of chitin with chitin-binding proteins, the regulation of genes responsible for chitin metabolism, and, finally, the targeting of chitin metabolism for insect-control purposes. Chitin is the major polysaccharide present in insects and many other invertebrates as well as in several microbes, including fungi. It serves as the skeletal polysaccharide of several animal phyla, such as the Arthropoda, Annelida, Molluska, and Coelenterata. In several groups of fungi, chitin replaces cellulose as the structural polysaccharide. In insects, it is found in the body wall or cuticle, gut lining or peritrophic matrix (PM), salivary gland, trachea, eggshells, and muscle attachment points. In the course of evolution, insects have made excellent use of the rigidity and chemical stability of the polymeric chitin to assemble both hard and soft extracellular structures such as the cuticle (exoskeleton) and PM respectively, both of which enable insects to be protected from the environment while allowing for growth, mobility, respiration, and communication. All of these structures are primarily composites of chitin fibers and proteins with varying degrees of hydration and trace materials distributed along the structures.
Shrimp shells from Penaeus Vannamei species were hydrolyzed for chitin extraction by a chemical and a papain enzymatic method. Composition of shells was analyzed and their microstructure was characterized before and after hydrolysis by microscopy. Chitin fibers arrangement in the tissue was preserved after chemical extraction, but after papain hydrolysis the tissue presented structural disarrangement indicating that papain reacts indistinctly with peptidic and N-acetyl linkages. Although chemical purification is very effective, by-products are not recoverable. Conversely, papain hydrolysis yields partially purified chitosan but permits aminoacids isolation, which is important in food industry. This method has other advantages such as low cost and easy accessibility of papain. Chitin and chitosan were characterized by thermogravimetric analysis, infrared spectrophotometry and capillary electrophoresis. Degree of N-acetylation (DA) was determined by cross-polarization magic angle spinning nuclear magnetic resonance (CPMAS 13CNMR) or potentiometry and crystallinity was measured by X ray diffraction.
Over the past several decades, we have witnessed significant progress in chitosan and chitin based nanostructured materials. The nanofibers from chitin and chitosan with appealing physical and biological features have attracted intense attention due to their excellent biological properties related to biodegradability, biocompatibility, antibacterial activity, low immunogenicity and wound healing capacity. Various methods, such as electrospinning, self-assembly, phase separation, mechanical treatment, printing, ultrasonication and chemical treatment were employed to prepare chitin and chitosan nanofibers. These nanofibrous materials have tremendous potential to be used as drug delivery systems, tissue engineering scaffolds, wound dressing materials, antimicrobial agents, and biosensors. This review article discusses the most recent progress in the preparation and application of chitin and chitosan based nanofibrous materials in biomedical fields.
Procedures for chitin nanofiber or nanocrystal extraction from Crustaceans modify the chitin structure significantly, through surface deacetylation, surface oxidation and/or molar mass degradation. Here, very mild conditions were used to disintegrate chitin fibril bundles and isolate low protein content individualized chitin nanofibers, and prepare nanostructured high-strength chitin membranes. Most of the strongly ‘bound’ protein was removed. The degree of acetylation, crystal structure as well as length and width of the native chitin microfibrils in the organism were successfully preserved. Atomic force microscopy and scanning transmission electron microscopy, showed chitin nanofibers with width between 3 and 4 nm. Chitin membranes were prepared by filtration of hydrocolloidal nanofiber suspensions. Mechanical and optical properties were measured. The highest data so far reported for nanostructured chitin membranes was obtained for ultimate tensile strength, strain to failure and work to fracture. Strong correlation was observed between low residual protein content and high tensile properties and the reasons for this are discussed.
Chitin extraction from shrimp shell using enzymatic treatment. Antitumor, antioxidant and antimicrobial activities of chitosan, International Journal of Biological Macromolecules (2014), http://dx.doi.org/10.1016/j.ijbiomac.2014.06.013 This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.
Carbohydrate Polymers j o u r n a l h o m e p a g e : w w w . e l s e v i e r . c o m / l o c a t e / c a r b p o l a b s t r a c t -Chitin nanofibers were fabricated with dried shrimp shells via a simple high-intensity ultrasonic treat-ment under neutral conditions (60 KHz, 300 W, pH = 7). The diameter of the obtained chitin nanofibers could be controlled within 20–200 nm by simply adjusting the ultrasonication time. The pulsed ultra-sound disassembled natural chitin into high-aspect-ratio nanofibers with a uniform width (19.4 nm after 30 min sonication). The EDS, FTIR, and XRD characterisation results verified that -chitin crystalline structure and molecular structure were maintained after the chemical purification and ultrasonic treat-ments. Interestingly, ultrasonication can slightly increase the degree of crystallinity of chitin (from 60.1 to 65.8). Furthermore, highly transparent chitin films (the transmittance was 90.2% at a 600 nm) and flexible ultralight chitin foams were prepared from chitin nanofiber hydrogels.
Chitin, obtained principally from crustacean waste, is a sugar-like polymer that is available at low cost. It has been shown to be bio- and ecocompatible, and has a very low level of toxicity. Recently, it has become possible to industrially produce pure chitin crystals, named "chitin nanofibrils" (CN) for their needle-like shape and nanostructured average size (240 × 5 × 7 nm). Due to their specific chemical and physical characteristics, CN may have a range of industrial applications, from its use in biomedical products and biomimetic cosmetics, to biotextiles and health foods. At present, world offshore disposal of this natural waste material is around 250 billion tons per year. It is an underutilized resource and has the potential to supply a wide range of useful products if suitably recycled, thus contributing to sustainable growth and a greener economy.
Engineered tissues require enhanced organization of cells and extracellular matrix (ECM) for proper function. To promote cell organization, substrates with controlled micro- and nanopatterns have been developed as supports for cell growth, and to induce cellular elongation and orientation via contact guidance. Micropatterned ultra-thin biodegradable substrates are desirable for implantation in the host tissue. These substrates, however, need to be mechanically robust to provide substantial support for the generation of new tissues, to be easily retrievable, and to maintain proper handling characteristics. Here, we introduce ultra-thin (<10 μm), self-assembled chitin nanofiber substrates micropatterned with replica molding for engineering cell sheets. These substrates are biodegradable, mechanically strong, yet flexible, and easily manipulated into the desired shape. As a proof-of-concept, fibroblast cell proliferation, elongation, and alignment were studied on the developed substrates with different pattern dimensions. On the optimized substrates, the majority of the cells aligned (<10°) along the major axis of micropatterned features. With the ease of fabrication and mechanical robustness, the substrates presented herein can be utilized as versatile system for the engineering and delivery of ordered tissue in applications such as myocardial repair.
Chitin and Chitosan are polysaccharide polymers. Polysaccharide is a carbohydrate whose molecules consist of a number of sugar molecules bonded together. It contains more than 5,000 acetylglucosamine and glucosamine (sugar) units, respectively and their molecular weights are over one million Daltons. Most of the naturally occurring polysaccharides are neutral or acidic in nature, whereas Chitin and Chitosan are examples of highly basic polysaccharides. Chitin is isolated from crab and shrimp waste and is a renewable resource. It is widely accepted that this biopolymer is an important biomaterial in many aspects. This review explores the various aspects of Chitin research.
Gelatin/chitin nanofibers were prepared by electrospinning. Various solutions were obtained by mixing a 27 % (w/v) gelatin in formic acid solution with crab shell chitin dissolved in a mixture of trichloroacetic acid and formic acid in 1:4 volume ratios. Obtaining electrospinnable gelatin/chitin solutions required the decrease of chitin molecular mass. Two types of depolymerisation processes were tested: microwave irradiation and ultrasonic treatment. By variation of irradiation parameters, an optimum was found with the microwave reactor working in temperature control mode. The chemical and physical structure of the gelatin/chitin nanofibers were investigated by scanning electron microscopy and infrared spectroscopy.
Research into renewable chemicals, fuels and materials sourced from the oceans at Memorial University and elsewhere is employing green chemical technologies for the transformation of algae and food industry waste streams into useful products. A very small proportion of biomass utilization research is currently focused on these feedstocks and efforts focused in this area could reduce land space competition between food and chemical/fuel production. This perspective highlights some of the achievements and potential opportunities surrounding the use of algae and waste from shellfish and finfish processing. In particular, investigations in this field have used alternative solvents (water, supercritical carbon dioxide and methanol or ionic liquids) extensively. Supercritical Fluid Extraction (SFE) has been used to extract lipids and pigments from algae, and oils from fish-processing plant waste streams. Water can be used to isolate potentially high value biologically-active oligosaccharides from some seaweeds. Biotechnological approaches are showing promise in the separation of biopolymers from shellfish waste streams. Production of new nitrogen-containing bioplatform chemicals (e.g. 3-acetamido-5-acetylfuran) from aminocarbohydrates (chitin, chitosan and N-acetylglucosamine) is being pursued.
Chitin is widely distributed in nature, constituting an important renewable resource. The main sources of chitin generally used are the crustacean wastes of the fishing industry. This chapter provides a brief account of the main processes employed in chitin isolation and the preparation of chitosan by extensive deacetylation of chitin. The common methods of characterization of chitin and chitosan, in terms of degree of acetylation and molecular weight, are discussed. Their crystalline structure and their solution properties, are also described. The capacity of chitin and chitosan of forming complexes with metal ions is shown, and mention is made to some of its diverse applications. The ability of chitosan to form polyelectrolyte complexes with polyanions, the cooperativity of this reaction and the properties of chitosan-based polyelectrolyte complex membranes, are also examined. The chapter ends with a review of the applications of chitin and chitosan in medicine, pharmacy, agriculture, the food industry, cosmetics, among others.
Chitin and chitosan are considerably versatile and promising biomaterials. The deacetylated chitin derivative, chitosan is more useful and interesting bioactive polymer. Despite its biodegradability, it has many reactive amino side groups, which offer possibilities of chemical modifications, formation of a large variety of useful derivatives that are commercially available or can be made available via graft reactions and ionic interactions. This study looks at the contemporary research in chitin and chitosan towards applications in various industrial and biomedical fields.
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.
Biomass is now regarded as a potential feedstock to produce renewable valuable chemicals that can be derived from sugar. In this study, it was demonstrated that Fe/HY catalyst was able to promote the hydrolysis in ionic liquid of oil palm biomass to reducing sugar without a prior pretreatment step. Initially, cellulose was utilized as a model compound and the effects of several variables including temperature, time, catalyst loading, cellulose loading, and 1-butyl-3-methylimidazolium bromide (BMIMBr) purity on the hydrolysis process were evaluated. A total reducing sugar (TRS) yield of 60.8% was obtained using Fe/HY catalyst in BMIMBr at 120 °C within 3 h. Next, the same catalyst was applied for direct hydrolysis of oil palm frond (OPF) and empty fruit bunch (EFB). The TRS yields obtained were 27.4% and 24.8%, respectively, while the efficiencies were 54.6% and 58.5% for OPF and EFB, respectively. The catalyst, tested for five runs, exhibited a minimal loss in the catalytic activity signifying its potential recyclability ability. Further conversion of the cellulosic hydrolysate led to promising levulinic acid yield and process efficiency. The experimental results confirmed that Fe/HY catalyst and BMIMBr have the potential to be used in a lignocellulosic biorefinery at mild process conditions for processing renewable feedstocks.
Catalytic hydrolysis of cellulose into reducing sugar (RS) over solid acid catalysts is one of efficient pathways for the conversion of biomass into fuels and chemicals. In this study, we developed a new method for the hydrolysis of cellulose into RS in ionic liquids catalyzed by a core-shell Fe3O4@SiO2-SO3H acid catalyst, which was prepared by the immobilization of sulfonic acid groups on the surface of silica-encapsulated Fe3O4 nanoparticles. The effect of various reaction parameters, such as reaction temperature, catalyst loading and the amount of water used, were studied. The Fe3O4@SiO2-SO3H showed a good activity with RS yield of 73.2% under the moderate conditions of 130 degrees C after 8 h reaction. Importantly, the catalyst Fe3O4@SiO2-SO3H could be easily separated from reaction mixtures by a permanent magnet. In addition, the catalyst showed a high stability during the hydrolysis of cellulose and it could be reused for several times without the significant loss of its activity.
Recent developments in the fabrication of nano- and microstructured chitin materials are reviewed, specifically focusing on approaches through gelation with suitable dispersion media. Although chitin is one of the most abundant natural polysaccharides, it is under-used as a result of its poor solubility and difficulties in processing. The dissolution of chitin in different solvent systems, including ionic liquids, has been investigated for the production of various materials. For example, the ionic liquid 1-allyl-3-methylimidazolium bromide dissolved chitin at concentrations up to 5% w/w and formed ion gels at higher concentrations of chitin. A highly concentrated solution of CaBr2·2H2O/methanol also induced the gelation of chitin. As one of the most efficient methods of production of nanomaterials from chitin, self-assembled nanofibers have been fabricated by regeneration from solutions or gels of chitin with the appropriate solvents and dispersion media using a bottom-up approach. For example, a chitin ion gel with 1-allyl-3-methylimidazolium bromide was regenerated using methanol to produce a chitin nanofiber dispersion, which was then used to construct a film with a highly entangled nanofiber morphology by filtration. Physical and chemical approaches have been investigated for the fabrication of composite materials of self-assembled chitin nanofibers with other polymeric components. Poly(vinyl alcohol) and carboxymethyl cellulose were made compatible with chitin nanofibers by co-regeneration and electrostatic interaction procedures, respectively. Surface-initiated graft polymerization of some monomers from chitin nanofiber films with the appropriate initiating groups have been conducted using the latter approach to obtain composite films covalently linked to graft chains on the nanofibers. Regeneration from gels with CaBr2·2H2O/methanol resulted in the efficient production of microporous materials.
In this study, α-chitin nanofibers (CNFs)–poly(vinyl alcohol) (PVA) composite films were fabricated to evaluate the compatibility and reinforcement effect of CNFs to PVA. CNFs were disintegrated by one-pass grinding and 40-min ultrasonication. The diameter of most of CNFs ranged from 30 nm to 50 nm. The CNFs–PVA composite films were made by immersing CNFs sheet into PVA solution. FTIR and XRD analysis revealed that there are strong interaction and good compatibility between CNFs and PVA molecular. In comparison with the neat PVA film, the light transmittance of the composite film slightly decreased from 92% to 86%. The coefficient of thermal expansion dramatically decreased from 123.62 ppm K−1 to 25.09 ppm K−1. The tensile strength and Young’s modulus were high to 127 MPa and 5.70 GPa, which were about 100% and 140% larger than those of the PVA film. The elongation at break point of the composite film decreased from 20.70% to 4.40%.
A highly porous and spongy monolith cryogel was prepared by a single freeze–thawing cycle of a PVA solution containing chitin nanofibrils (CNFs) as the nanofiller and glutaraldehyde (GA) as the cross-linker. The presence of CNFs significantly reinforced the spongy structure of the cryogel so that repeated squeezing–releasing did not deteriorate its spongy structure. The in situ self-polymerized polydopamine was formed inside the spongy cryogel by soaking the cryogel in a dopamine solution. The polydopamine modified cryogel (PVA–CNF–D) showed a very good antioxidant activity in that approximately 49% of free radicals of DPPH˙ was consumed within 2 min. Silver nanoparticles (SNPs) could be spontaneously reduced from silver nitrate solution and deposited onto the polydopamine modified surface without an exogenous reducing reagent. The SNP incorporated spongy cryogel demonstrated a very effective antibacterial activity against E. coli.
Chitin nano-objects become more interesting and attractive material than native chitin because of their
usable form, low density, high surface area and promising mechanical properties. This work suggests a
straightforward and environmentally friendly method for processing chitin nanofibers using dynamic
high pressure homogenization. This technique proved to be a remarkably simple way to get -chitin into
-chitin nanofibers from yellow lobster wastes with a uniform width (bellow 100 nm) and high aspect
ratio; and may contributes to a major breakthrough in chitin applications. Moreover, the resulting -
chitin nanofibers were characterized and compared with native -chitin in terms of chemical and crystal
structure, thermal degradation and antifungal activity. The biological assays highlighted that the nano
nature of chitin nanofibers plays an important role in the antifungal activity against Aspergillus niger.
In this study, we investigated the preparation of chitin nanofiber (CNF)-reinforced carboxymethyl cellulose (CMC) films by their electrostatic interaction. First, CMC films and self-assembled CNF dispersions with methanol were prepared by casting technique and regeneration from chitin ion gels with an ionic liquid, respectively. Then, the CMC films were immersed in the dispersions with the different CNF contents, followed by centrifugation to obtain the desired composite films. The amounts of the absorbed CNFs on the films were calculated by the weight increases after the above compatibilization procedure. The presence of CNFs on the films was also confirmed by the SEM and IR measurements. The mechanical properties of the composite films were evaluated by tensile testing, which suggested the reinforcing effect of CNFs present on the CMC films.
Chitosan (CS) has been extensively studied and found wide applications in the field of biomedicine because of its favorable biological properties. Normal CS fibers are manufactured either by wet-spinning or by dry-jet wet-spinning. However, the poor tensile strength of CS fibers raises much concern. The present study uses chitin nanocrystal (ChiNC), a stiff rod-like nanofiller, to enhance the mechanical properties of wet-spun CS fibers. Owing to the good compatibility between CS and ChiNC, the nanoparticles are well distributed in the CS matrix. When the ChiNCs loading is 5 wt %, the optimal mechanical properties of CS fibers are obtained, and the peak stress is 2.2 cN/dtex and modulus is 145.6 cN/dtex, which are increased by 57% and 84.5%, respectively, compared to that of nonfilled CS fibers under the same processing condition. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40852.
Bionanocomposite sponge composing of cellulose nanofiber (CLNF), chitin whisker (CTW), and sericin (SRC) was developed. SRC—a glue-like protein found in silk cocoons—has several beneficial properties for wound care such as good skin moisturizing ability, antioxidant, and wound healing ability. However, pure SRC is generally difficult to be fabricated due to its weak structural properties. In the present study, this limitation of the SRC was overcome by using CLNF as a supporting material because of its nanofibrillar structure with high aspect ratio. CTW was chosen as another component due to its ability to promote tissue repair of wound. The CLNF/CTW/SRC sponges having different blend compositions were fabricated by the freeze-drying process and then treated with glutaraldehyde vapor to achieve structural stability. Effect of the blend composition on chemical structure and morphology of the bionanocomposite sponges were determined by Fourier transform infrared spectroscope (FTIR) and scanning electron microscope (SEM), respectively. Water absorption property was studied in terms of the blend composition and glutaraldehyde concentration. To clarify their possibility to be a potential wound care product, release profiles of the SRC from bionanocomposite sponges were investigated. Effects of the blend compositions, the presence of lysozyme, and NaCl concentration were observed.
Chitosan-sheath and α-chitin-core nanowhiskers (CsNWs) have been successfully generated by surface deacetylation of chitin nanowhiskers (CtNWs) in the never-dried state. Acid hydrolysis (3N HCl, 30 mL/g, 104 °C) of pure chitin derived from crab shell yielded 65% 4–10 nm thick, 16 nm wide and 214 nm long chitin whiskers (CtNWs) that were 86% crystalline and 81% acetylated. Surface deacetylation of CtNWs was robust in their never-dried state in 50% NaOH at a moderate 50 °C for 6 h, yielding 92% CsNWs. All deacetylated CsNWs retain the same α-chitin crystalline core at reduced 50% crystallinity and similar dimensions (4–12 nm thick, 15 nm wide, 247 long) as CtNWs, but reduced 60% acetylation reflecting the deacetylated surface layers. Progressive surface deacetylation was evident by the increased IP as well as increased positive charges under acidic pH and reduced negative charges at alkaline pH with increasing reaction time.
This paper examines the effect of biobased chitin nanowhisker fillers on the thermal, rheological, physical, mechanical and morphological properties of biobased polylactic acid (PLA) and PLA/polyhydroxybutyrate-co-valerate (PHBV) blended nanocomposites as well as the physical, mechanical and morphological properties of porous PLA and PLA/PHBV nanocomposite foams. Solid nanocomposites of PLA, PLA/PHBV and chitin nanowhiskers were manufactured through melt blending while porous nanocomposites foams were fabricated through a batch foaming process with the aid of CO2 as blowing agent. It was found that by incorporating small quantities of chitin nanowhiskers (<2 wt%) the mechanical properties of solid specimens are improved while strength and expandability of the foam can be significantly improved, yielding a homogenously distributed cell morphology with average cell size of 1.5 μm.
Nanocomposite gels containing chitosan as a network polymer and chitin nanowhiskers as reinforcing fillers were prepared by cross-linking with the blocked isocyanate hexamethylene-1,6-di-(aminocarboxysulfonate) (HDS). Young's modulus and stress at break of the nanocomposite gels increased to maximum values of 169 and 135 kPa, respectively, with increase in whisker content up to 13.3%, whereas the degree of swelling decreased from 357 to 33.0. Polymer Journal (2012) 44, 713-717; doi: 10.1038/pj.2012.11; published online 14 March 2012
Chitosan membrane possesses huge potential application in many fields, such as biomedicine, waste-water purification and environmental protection, however, the poor mechanical property restricts its further development. In this study, chitin whisker was prepared by hydrolysis method, and was firstly used as an interlayer to fabricate the multilayered chitosan membrane through layer-by-layer method, which is inspired by the natural materials' hierarchical structure. From the results of mechanical testing, it is shown that tensile strength of the multilayered chitosan membranes reaches up to 122.8 MPa, which is about 2.5 times than that of neat chitosan membrane (i.e. 49.5 MPa), and the elongation at break is sharply increased as well. Crown Copyright
In this paper, rod-like chitin whisker was used as a filler to reinforce the chitosan membrane, and a series of composite membranes were prepared by casting-evaporation method. Mechanical testing shows that tensile strength of the resulting composite membrane with 3(wt.)% chitin whisker content reaches up to 110.3MPa, which is about 2.8 times than that of neat chitosan membrane (38.5MPa), and moisture regain of all composite membranes presents a decreasing tendency with increasing content of chitin whisker. Furthermore, SEM was used to investigate the morphology difference between neat chitosan membrane and composite membranes, to understand the reinforce mechanism of chitin whisker. Wide angle x-ray diffraction and Fourier transform infrared spectroscopy were used to visualize the structure change before and after the compositing processes. Besides, the bacterostatic test shows that this composite membrane presents effective inhibitory effect on Staphylococcus aureus, Escherchia coli and Corinebaterium michiganence respectively, which indicates it a promising material for packaging and wound dressing.
An environmentally friendly approach was implemented for the production of nanocomposites with bactericidal activity, using bacterial cellulose (BC) nanofibers and chitin nanocrystals (ChNCs). The antibacterial activity of ChNCs prepared by acid hydrolysis, TEMPO-mediated oxidation or partial deacetylation of α-chitin powder was assessed and the structure of the ChNC nanoparticles was characterized by X-ray diffraction, atomic force microscopy, and solid-state 13C-NMR. The partially deacetylated ChNCs (D-ChNC) showed the strongest antibacterial activity, with 99 ± 1% inhibition of bacterial growth compared to control samples. Nanocomposites were prepared from BC nanofibers and D-ChNC by (i) in situ biosynthesis with the addition of D-ChNC nanoparticles in the culture medium of Acetobacter aceti, and (ii) post-modification by mixing D-ChNC with disintegrated BC in an aqueous suspension. The structure and mechanical properties of the BC/D-ChNC nanocomposites were characterized by Fourier transform infrared spectroscopy, elemental analysis, field-emission scanning electron microscopy, and an Instron universal testing machine. The bactericidal activity of the nanocomposites increased with the D-ChNC content, with a reduction in bacterial growth by 3.0 log units when the D-ChNC content was 50%. D-ChNC nanoparticles have great potential as substitutes for unfriendly antimicrobial compounds such as heavy metal nanoparticles and synthetic polymers to introduce antibacterial properties to cellulosic materials.
Nanocomposite fiber mats based on biodegradable polycaprolactone (PCL) and chitin nanofibril (n-chitin) were produced via electrospinning. The morphologies, thermal and mechanical properties as well as surface wettability of the fiber mats were studied by scanning electron microscopy, differential scanning calorimetry analysis, thermogravimetric analysis, dynamic mechanical analysis and static water-contact-angle analysis, respectively. The addition of chitin nanofibrils into PCL resulted in a small change in thermal behavior, but a significant improvement in mechanical properties. Moreover, the surface wettability of electrospun fiber mats transformed from hydrophobicity to hydrophilicity when the chitin nanofibril content was more than 25wt%. In addition, in vitro cell culture results indicated that the addition of chitin nanofibrils can strongly improve the cellular infiltration and migration confirming that the chitin nanofibril was a good reinforcing as well as bioactive filler for PCL.
Surface-deacetylated chitin nanofiber films plasticized with glycerol were prepared to control mechanical properties. Nanofiber networks were able to retain excessive glycerol content up to 70% to obtain self-standing film. All films were flexible and highly transparent independent of glycerol content. Glycerol significantly decreased the Young's moduli and tensile strengths, and increased the fracture strain due to its plasticizing effect. At the same time, glycerol did not change the high transparency or the low thermal expansion of the nanofiber film.
Nanocomposite fiber mats based on biodegradable polycaprolactone (PCL) and chitin nanofibril (n-chitin) were produced via electrospinning. The morphologies, thermal and mechanical properties as well as surface wettability of the fiber mats were studied by scanning electron microscopy, differential scanning calorimetry analysis, thermogravimetric analysis, dynamic mechanical analysis and static water-contact-angle analysis, respectively. The addition of chitin nanofibrils into PCL resulted in a small change in thermal behavior, but a significant improvement in mechanical properties. Moreover, the surface wettability of electrospun fiber mats transformed from hydrophobicity to hydrophilicity when the chitin nanofibril content was more than 25 wt%. In addition, in vitro cell culture results indicated that the addition of chitin nanofibrils can strongly improve the cellular infiltration and migration confirming that the chitin nanofibril was a good reinforcing as well as bioactive filler for PCL.
Shape-memory bionanocomposites based on a naturally sourced segmented thermoplastic polyurethane and chitin nanocrystals were synthesized and their mechanical properties and thermally-activated shape-memory behavior were studied. The chitin nanocrystals were incorporated during the synthesis of the prepolymer made from a castor oil-based difunctional polyol and hexamethylene diisocyanate. The polymerization was completed by addition of propanediol, as a corn-sugar based chain extender, bringing the weight content of components from renewable resources to >60%. Thermal analysis of the bionanocomposites revealed a phase-separated morphology, which is composed of soft and hard domains, which bestow the material with two melting transitions at 60 and 125 ºC, that are exploitable for a shape memory effect. The soft segment is responsible for temporary shape fixing, while the hard segment crystallites are responsible for the permanent shape. The introduction of small amounts (0.25-2 wt%) of chitin nanocrystals was found to increase the crystallinity of the hard segment by way of nucleation, which in turn improves the shape recovery considerably. The thermally-activated shape-memory behavior of the synthesized bionancomposites is exploitable with a programming and release temperature of 60 ºC. The materials display good in vitro cell response, as shown by short-term cytotoxicity assays, and therefore, the bionanocomposites appear to be potentially useful for biomedical applications.
Melanoidins, the complex bio-polymer of amino-carbonyl compounds are widely distributed in food, drinks but if it was discharged into a water resource system that affect as environmental pollutants. Adsorption is a potential method to remove the color from the food or environment. Therefore, this research studied on the adsorption of synthetic melanoidins by chitin nanofibers prepared from shrimp shell waste. The results showed that the adsorption of melanoidins with chitin nanofibers was increased when increasing temperature, giving values of 131, 331 and 353mg/g at 20°C, 40°C and 60°C, respectively, which were higher than other chitin-derived adsorbents. In addition, the b value of chitin nanofibers also had a high affinity and strength for melanoidins adsorption at low concentration higher than other chitin-derived adsorbents. The results from Fourier transform infrared (FT-IR) spectroscopy and elution studies confirmed that the interaction between melanoidins and chitin nanofibers involved both electrostatic and chemical adsorption. For application in the sugar industry, chitin nanofibers can be used for adsorption of melanoidins and other pigments from sugar syrup.
Isolation of cellulose from straw is a bottleneck for exploiting such biomass resources. In recent years, considerable concerns have arisen over new efficient and environmentally friendly way for this purpose. A novel method for cellulose isolation has been proposed by dissolving steam exploded rice straw in 1-allyl-3-methylimidazolium chloride ionic liquid (IL), following regeneration of crude cellulose by diluting the cellulose-ionic liquid solution adequately after separation of insoluble residues. The crude cellulose was then bleached by 2% hydrogen peroxide aqueous solution with low-flux ozone blowing into. No acid-insoluble lignin and only 0.85% hemicelluloses were detected in the bleached cellulose. The isolated cellulose was analyzed by SEM, FT-IR, 13C CP/MAS solid state NMR, XRD spectroscopes, and the results indicated that high quality cellulose preparation could be isolated in this manner from rice straw.