Nanochitin Research Articles

Lipase etching effects-induced interaction between betanin nanocomplexes and polylactic acid and its 3D printing for food packaging

Etching effects by lipase on polylactic acid (PLA) could induce the exposure of active sites and promote the attachment of betanin nanocomplexes (BR-Ch) to obtain red color. 3D printing, regarded as emerging, innovative packaging fabrication technique, was applied to potentially develop creative, red PLA products for food application. BR-Ch was prepared based on betanin and nano chitin (around 195 nm) via electrostatic interaction and hydrogen bonding, obtaining nanocomplexes (around 24 nm) with excellent thermal stability. Pre-treatments mattered greatly in PLA functionalization, and especially, lipase pre-treatment 30 min promoted BR-Ch modification on PLA. Final PLA exhibited excellent red color characteristics (CIElab, Hue-Saturation-Brightness, K/S and CMYK), elongation at break and stable thermal resistance, ultimately achieving outstanding dyeing effect. This work indicates that BR-Ch can potentially replace synthetic pigments to functionalize lipase-pretreated PLA, and the dyed PLA demonstrate the excellent packaging application prospects in food field by 3D-printed products.

High internal phase Pickering emulsions via complexation of cellulose nanofibrils and nanochitin: Enhanced interfacial adsorption and structured aqueous network

High internal phase emulsion is a novel emulsion type for a range of applications, while its preparation is limited by low stability and the selection of proper emulsifiers. Herein, an edible sunflower oil-in-water high internal phase Pickering emulsion (HIPPE) stabilized by complexation of cellulose nanofibrils (CNF) and nanochitin (NCh) is prepared using a two-step method. The stabilization capacity of the CNF/NCh complexes stems from restricted coalescence, droplet breakage, and coarsening upon HIPPE formation, showing the minimal droplet size at 80 μm. This is the result of a dual stabilization mechanism including: enhanced adsorption of the complexes at the oil-water interfaces by existence of the acetyl groups in the complexes and structuring the aqueous phase to form networking structures within HIPPEs. The CNF/NCh complex suspensions exhibit tolerance to changes in pH (3–5) and salinity (0–500 mM), showing capability of forming and stabilizing HIPPEs with minimal alteration to droplet size and morphology. The complex-stabilized HIPPEs remain stability after at least 2-year storage at ambient condition. Overall, complexation of CNF and NCh greatly extend the conditions on forming highly stable, tuneable HIPPEs, offering potential on engineering applications relevant to clean-label, green foodstuffs.

Gradient heating activated ammonium persulfate oxidation for efficient preparation of high-quality chitin nanofibers

APS is a cheap and eco-friendly oxidant which enables one-step extraction of nanochitin (NCh) from fishery wastes. However, it is challenging to improve the preparation efficiency and NCh quality simultaneously, owing to the uneven or uncontrollable oxidation. Herein, we propose a simple and controllable way to isolate chitin nanofibers (ChNFs) from squid pen by gradient heating activated (GHA)- ammonium persulfate (APS) oxidation. Compared to the isothermal activated (ITA)-APS oxidation, our strategy reduced the mass ratio of squid pen to APS from 1:45 to 1:6 and reaction time from 15 h to 8 h. Meanwhile, the as-prepared ChNFs exhibited high yield (91.5 %), light transmittance (98 % at 500 nm), crystallinity index (96.9 %), and carboxyl content (1.53 mmol/g). GHA-APS oxidation involved multiple continuous heating and isothermal stages. The former stimulates a moderate activation of APS and enhances the oxidation rate, while the latter provides a duration for surface chemistry. This non-isothermal heating facilitates the continuous decomposition of APS at a relatively high and consistent rate, thereby enhances its oxidation efficiency. Furthermore, green assessments indicate this method is simple, time-saving, eco-friendly and cost-effective. Overall, this work introduces a novel perspective for the industrial extraction of high-efficiency and high-quality nanomaterials.

Preparation and Application Prospects of Nano Chitin

Over recent years, the global ecological environment has deteriorated, and it is urgent to use environmentally friendly renewable energy as an alternative. Chitin nanofiber (ChNF) appears in the public view as a biomass material with biodegradability and biocompatibility. This paper elaborates on the preparation methods, application fields, and prospects of chitin nanofiber. Firstly, the preparation steps of chitin nanofibe including purification of chitin and the preparation of nano size chitin are listed. Based on this, the common chitin purification methods, such as the acid-base method, Ethylene diamine tetra acetic acid (EDTA) auxiliary method, and microwave method, are discussed. In terms of the nano fibrillation, the mixing of chemical and mechanical methods is introduced to improve the products’ purity and yield. Secondly, due to the unique features of chitin nanofiber, its potential in biomedical, food security, and absorbent for waste water treatment is promising. However, the large-scale application of nano chitin still faces some obstacles including large energy consumption in the preparation process, high catalyst treatment cost, and unstable production rate. This paper expects that future researchers can focus on achieving the large-scale and high-quality production of chitin nanofiber and exploring its great potential.

Lyophilized biocomposite chitin-alginate matrices for wound healing application

BackgroundWound management is a significant part of the health care segment with an ever-increasing patient base. The field of wound dressings has evolved over the time from using natural materials that only provided protection to the wounds to advanced wound dressings that also aid in healing process in addition to providing protection. The use of lyophilized non-woven composite dressings is an appealing prospect in the field of wound dressings. MethodsNano chitin was prepared using a combination of acid hydrolysis and ultrasonication. Wound healing matrices were fabricated from nano chitin – sodium alginate composite mixtures (2:1) using lyophilization technique. Glycerol was incorporated as plasticizer. Surface topography of the dressings was observed using Scanning Electron Microscopy and texture was analyzed by optical profilometry. The dressings were assessed for their wound healing potential on excision wound model in rats. The healing was assessed by measuring percentage wound contraction, histopathological studies and hydroxyproline content in the healed tissue. ResultsThe resulting dressings were soft with a highly porous morphology as observed in the SEM photomicrographs. The percentage wound contraction for wounds treated with composite dressings was 90.26 ± 3.98 as compared to 82.34 ± 5.10 for sodium alginate treated wounds at the end of 14 days. Histopathological studies showed increased fibroblast cells, restored adnexa and extensive collagen fibres and completely developed blood vessels in composite treated wounds. The hydroxyproline content in wounds treated with composite dressing was 66.87 and in those treated with sodium alginate dressing was 61.19. ConclusionThe results signify the potential of lyophilized chitin nanowhiskers-sodium alginate composites for wound healing application.

Heteroaggregation effects on Pickering stabilization using oppositely charged cellulose nanocrystal and nanochitin

Pickering emulsions are stabilized using complexes of cellulose nanocrystals (CNC) and nanochitin (NCh). The colloidal behavior and heteroaggregation in aqueous media are studied in relation to complex formation and net charge. The complexes are remarkably effective in stabilizing oil-in-water Pickering emulsions under conditions of slightly net positive or negative charges, as determined by the CNC/NCh mass ratio. Close to charge neutrality (CNC/NCh ~5), large heteroaggregates form, resulting in unstable emulsions. By contrast, under net cationic conditions, interfacial arrest of the complexes leads to non-deformable emulsion droplets with high stability (no creaming for 9 months). At given CNC/NCh concentrations, emulsions with up to 50% oil fraction are produced. This study shows how to control emulsion properties beyond consideration of the typical formulation variables, for instance, through adjusting CNC/NCh ratio or charge stoichiometry. We highlight the possibilities that are available for emulsion stabilization by using a combination of polysaccharide nanoparticles.

Influence of glucan on physicochemical and rheology properties of chitin nanofibers prepared from Shiitake stipes

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.

Preparation, Characterization and Gelation of a Fungal Nano Chitin Derived from Hericium erinaceus Residue.

Nano chitin is a promising biocompatible material with wide applications. In this work, a fungal-derived nano chitin was prepared from Hericium erinaceus residue via mineral/protein purification and subsequent TEMPO-mediated oxidation. The structure, dispersity, and gelation ability of the prepared fungal nano chitin were studied. The results showed that the average length and width of the prepared fungal nano chitin were 336.6 nm and 6.4 nm, respectively, and the aspect ratio exceeded 50:1. The nano chitin retained the basic structure of chitin, while the crystallization index was improved. In addition, the dispersity of the nano chitin in aqueous media was evaluated by the effective diameter, and the polydispersion index was mainly affected by pH and ionic strength. Under acetic acid “gas phase coagulation”, the prepared nano chitin dispersions with mass concentrations of 0.2, 0.4, 0.6, and 0.8% were converted into gels by enhanced hydrogen bond crosslinking between nano chitins.

Immobilization of phlorotannins on nanochitin: A novel biopreservative for refrigerated sea bass (Lateolabrax japonicus) fillets

A novel biopreservative was developed by immobilizing phlorotannins into nanochitin (NCh). NCh were selected as a host complex to immobilized phlorotannins and the structural properties and antioxidant activity of the NCh-phlorotannins nanocomplex was investigated. The NCh-phlorotannins showed high antioxidant activity, as evidenced by free radical scavenging activity test. Moreover, the effects of NCh-phlorotannins on physical [color, water holding capacity (WHC), and texture], chemical [thiobarbituric acid (TBA) values, total volatile base nitrogen (TVB-N), and pH], microbiological [total viable count], changes of refrigerated sea bass (Lateolabrax japonicus) fillets were also evaluated. Sea bass fillets add with 1.5 g/kg NCh-phlorotannins had lower bacterial growth, pH, TVB-N and TBA as well as better characteristics of texture, color, and WHC than those of the control group during refrigerated storage. The efficiency of NCh-phlorotannins treatment was also better than that of phlorotannins or NCh treatment alone. Therefore, NCh-phlorotannins may be a potential biopreservative to extend the shelf-life of sea bass fillets quality during refrigerated storage.

Anion-Specific Water Interactions with Nanochitin: Donnan and Osmotic Pressure Effects as Revealed by Quartz Microgravimetry.

The development of new materials emphasizes greater use of sustainable and eco-friendly resources, including those that take advantage of the unique properties of nanopolysaccharides. Advances in this area, however, necessarily require a thorough understanding of interactions with water. Our contribution to this important topic pertains to the swelling behavior of partially deacetylated nanochitin (NCh), which has been studied here by quartz crystal microgravimetry. Ultrathin films of NCh supported on gold-coated resonators have been equilibrated in aqueous electrolyte solutions (containing NaF, NaCl, NaBr, NaNO3, Na2SO4, Na2SO3, or Na3PO4) at different ionic strengths. As anticipated, NCh displays contrasting swelling/deswelling responses, depending on the ionic affinities and valences of the counterions. The extent of water uptake induced by halide anions, for instance, follows a modified Hofmeister series with F– producing the highest swelling. In marked contrast, Cl– induces film dehydration. We conclude that larger anions promote deswelling such that water losses increase with increasing anion valence. Results such as the ones reported here are critical to ongoing efforts designed to dry chitin nanomaterials and develop bio-based and sustainable materials, including particles, films, coatings, and other nanostructured assemblies, for various devices and applications.

The The Effect of Alginate, Chitosan, and Nano Chitin as Encapsulation Materials of <em>L. casei</em> Probiotic Bacteria

Alginate, nano chitin, and chitosan polymers can be used to protect the Lactobacillus casei from gastric conditions. The goal of this study was to determine the effect of alginate, nano chitin, and chitosan as encapsulation materials of L. casei on their survivability in simulated gastric fluid (SGF). The encapsulation process in this study was carried out by the extrusion method. The resulted beads were soaked in SGF (pH of 1.2 and 3) for 1 and 60 min at 37°C. In SGF pH 1.2 for 60 min, the survivability of L.casei in all variations of the experiment was 0% except those encapsulated from alginate (1%), nano chitin (0.2%), and chitosan (0.2) % of 75.35%. In SGF pH 3 for 60 min, the survivability of L.casei was 0% for beads unencapsulation and encapsulation made from alginate, while the highest survivability of L.casei was 81.22% obtained in various encapsulation experiments using alginate (1%), nano chitin (0.2%), and chitosan (0.2%). The addition of nano chitin or chitosan to L.casei encapsulation material can increase the survivability of L.casei, also showed that the combination of alginate, nano chitin, and chitosan in the encapsulated material significantly increased the survivability of L.casei at SGF pH 1.2 and 3.

Fabrication of glycerophosphate-based nanochitin hydrogels for prolonged release under in vitro physiological conditions

Partially deacetylated nanochitin (NCh)/glycerophosphate (GP)-based composite hydrogels were prepared for the prolonged release of microemulsions (ME) under in vitro physiological conditions. Thermo-sensitive gelation behavior not be observed for the NCh/GP composite dispersion; however, the addition of glycerophosphate also resulted in the loss of viscoelasticity due to the sodium component in the β-glycerol phosphate disodium salt pentahydrate. To prepare enhanced NCh/GP composite hydrogels, a gas phase coagulation bath was further applied to introduce physical crosslinking domains in hydrogels. The storage modulus reached approximately 1600 Pa, as 20 μL GP was composited with NCh dispersion (0.6 wt %, 2 mL), and a higher GP dosage also led to decreased mechanical strength of composite hydrogels. Because of the relatively stable inter-structure, less than 40% of ME could be released from the NCh/GP composite hydrogel. To promote the release performance of NCh/GP-based composite hydrogels, chitosan and glycine were added. As high as 81% ME could be released from composite hydrogels at 40 °C in 50 h, as the mass ratio between NCh and chitosan was 2:1, while as high as 82% ME could be released at 40 °C in 50 h, as the mass ratio between NCh and glycine was 1:1. Moreover, obvious thermo-responsive release could be observed for the NCh(1)/Gly(1)/GP sample.

Scale-up of non-toxic poly(butylene adipate-co-terephthalate)-Chitin based nanocomposite articles by injection moulding and 3D printing

Poly(butylene adipate-co-terephthalate) (PBAT), a compostable polymer, filled with different weight percentage of unbleached nano chitin (NC; 10%, 30% and 50%), a biodegradable filler from crustacean waste, were prepared from the extruded blends by injection moulding and 3D printing. The nanochitin required was prepared from chitin isolated from prawn shells (Fenneropenaeus indicus). The nanochitin crystals were observed to contain carboxylic acid surface functional groups as assessed by FT-IR, 13C solid state NMR (SS NMR) spectroscopy, zeta potential measurements and the extent of the same was estimated by potentiometric titration. The PBAT-NC nanocomposites were characterized SS NMR spectroscopy, FT-IR spectroscopy, wide angle X-ray diffraction, dynamic mechanical analysis, DSC and TGA. Thermal and mechanical properties of the nanocomposites were determined. The moulded nanocomposites changed more and more rigid with increasing weight percentage of NC without significant change in the tensile strength. The TGA indicated that the thermal stability of PBAT could be improved but not significantly by the addition of NC. Wound healing was enhanced in the presence of the nanocomposite while in vivo toxicity was significant at high concentration. The PBAT-NC nanocomposites could be moulded in to useful articles such as laptop charger cover, rat cover for washing machine, planters and key holders under conditions similar to that used in the processing of LDPE.

Molecular mechanism of nanochitin whisker elicits plant resistance against Phytophthora and the receptors in plants

Rod-like nanochitin (NC) whisker with cationic nature has a strong synergistic effect with fungicides on inhibition of tobacco root rot disease. This study we explored the activity of NC against Phytophthora and the mechanism for eliciting plant defense response and the receptors in planta. P. capsici isolates, model Nicotiana benthamiana plants and Arabidopsis thaliana were treated with 0.005% of NC suspension and 1 μM of flg22. Infection control efficacy against P. capsici isolates, biosynthetic enzyme activities and the PR genes expression were determined at different hours post treatment in plant. The infection control efficacy, ROS generation, and PTI maker gene expression were re-analyzed in A. thaliana Col-0, bak1 and cerk1 mutants. The results showed that NC did not exhibit inhibitory effect on vegetative growth of P. capsici, but enhanced the resistance against P. capsici by systemically enhanced phenylalanine ammonia-lyase activity and PR gene expression. P. capsici resistance, PTI maker gene promotion, and ROS production in A. thaliana induced by NC depended not only on chitin receptor CERK1, but also BAK1. NC and flg22 induced oomycete immunity through a mechanism of a cross-microbe protection via the BAK1-CERK1 pathway in plant, pointing to the complexity of the plant immunity system.

Physicochemical and biological properties of nanochitin—abamectin conjugate for Noctuidae insect pest control

Abamectin (Am) is an excellent biopesticide for insect pests control but environmental sensitivity and a short duration in conventional formulations limit its application in agriculture. In order to promote the dispersity, stability, and biological activity of Am, well-monodisperse nanochitin (NCh) and Am-loaded nanoparticles (NCh-Am) were prepared and examined in this study. NCh was prepared by ultrasonication combining with low concentration acidic hydrolysis and NCh-Am nanoparticles were combined by conjugation in dispersion naturally. The effective particle size of NCh was 110.6 ± 18.6 nm with cationic nature, while those of NCh-Am conjugates ranged from 160 to 700 nm based on the mixing ratio. The binding efficiency of Am to NCh in the conjugates reached 53.7 ± 7.6% in DI water at pH 6.2. The thermal stability and water solubility of Am were greatly promoted by NCh. The photodegradation of Am in the conjugates decreased 48% when exposed to UV light for 56 h. The conjugate containing half of Am showed significant control efficiency in larva growth and enhanced mortality against 2 instar larvae of noctuid. The results suggested that NCh significantly promoted Am water dispersity, thermal stability, and photostability, and effectively reduced pesticides dosage in insect pest control. This finding indicates that NCh-Am can be used as a new bioactive delivery system in future pest management.

Nanochitin-stabilized pickering emulsions: Influence of nanochitin on lipid digestibility and vitamin bioaccessibility

Nature-derived nanoparticles are increasingly being explored for their potential to regulate the digestion of ingested lipids. In this study, we examined the impact of emulsifier format (molecular versus particle) on the gastrointestinal fate of vitamin D3-fortified emulsions by measuring their physicochemical properties, microstructure, digestibility, and bioaccessibility using an in vitro human gastrointestinal tract (GIT) model. Nanochitin (NCh) was used as an example of a particle-based (Pickering) emulsifier, whereas Tween 80 (T80) was used as an example of a small molecule surfactant. A series of 2 wt% oil-in-water emulsions containing different initial levels and locations of nanochitin and Tween 80 were prepared: (i) nanochitin-emulsions (0.02 wt% NCh); (ii) Tween 80-emulsions (0.02 wt% T80); (iii) nanochitin-emulsions (0.02 wt% NCh) plus Tween 80 (0.02 wt% T80); and (iv) Tween 80-emulsions (0.02 wt% T80) plus nanochitin (0.02 wt% NCh). The nanochitin-emulsions were much more prone to droplet aggregation within the simulated GIT than the T80-stabilized ones. Lipid digestion was 30% less and vitamin bioaccessibility was 45% less for the nanochitin-emulsions than for the T80-stabilized ones. Adding T80 to the nanochitin-emulsions, increased the rate of lipid digestion, whereas adding nanochitin to the Tween 80-stabilized ones, decreased the rate. The reduction in lipid digestion and bioaccessibility in the emulsions containing nanochitin may have been for a number of reasons: the adsorbed nanochitin layer hindered the ability of lipase to reach the lipid phase; the nanochitin-coated droplets were highly aggregated in the GIT, which reduced the area of lipids accessible to the lipase; and, the cationic nanochitin bound to anionic bile acids, fatty acids, or lipase. Our results suggest that nanochitin slows down lipid digestion, which may be advantageous for developing high-satiety foods, but that it also reduces vitamin bioaccessibility, which would be undesirable from a nutritional perspective.

Mechanical Characteristics of Micro and Nano Silica, ZnO and Chitin Powder Filled Unsaturated Polyester Composites

Objectives: In this study stir processing method is used to increase the strength of polymer with the addition of reinforcements such as micro and nano silica, ZnO and chitin powder. Methods/Statistical Analysis: produced with this process are the production of parts having good resistance to solvents like HCl and H 2 SO 4 being environmental friendly. Silica (micro and nano), chitin and ZnO were added into polyester resin in different fractions as 2%,4%,6% and 10% through mechanical stirrer at 1000 rpm for 1 h. Accelerator and catalyst were added and stirred using a glass rod. The influence of ZnO nano particles with the addition of silica and chitin powder on the mechanical properties like tensile strength and hardness were investigated. The comparison of different weight fractions is also studied. Findings: By adding ZnO nano particles with micro silica and chitin the tensile property of polyester composite was increased. The hardness increased with the addition of Silica (micro and nano) and ZnO whereas, it decreased with the addition of chitin powder. Application/Improvements: Investigating the effect of Silica (micro and nano) and chitin in addition to the ZnO nano particles on the mechanical and micro structure of polyester composites.

Effect of corn oil on physical, thermal, and antifungal properties of gelatin-based nanocomposite films containing nano chitin

Effects of corn oil on physical and antifungal properties of gelatin nanocomposite films containing chitin nano fibers (N-chitin) were investigated in this study. Different concentrations of corn oil (0.10, 0.20, and 0.30; g/g of dry gelatin) and (0.05 g/g of dry gelatin) N-chitin were used to prepare an emulsion nanocomposite gelatin film. Subsequently, characteristics of films were assessed by analyzing moisture content, solubility, hydrophobicity of the surface, water vapor permeability (WVP), as well as mechanical, thermal, and antifungal properties. The results obtained showed that films containing N-chitin had better mechanical properties than net gelatin film. In addition, N-chitin decreased film tendency to water absorption. However, because both gelatin and N-chitin have hydrophilic nature, nanocomposite films were still wettable. In this sense, incorporation of oil into film formulation improved barrier properties more than nanoparticles alone. In spite of the fact that gelatin films containing just N-chitin had antifungal properties, emulsion nanocomposite films did not show any antimicrobial activity. In addition, improving effect of oil on film properties was observed for concentrations up to 0.20 g/g, because films containing 0.30 g/g oil possessed weaker mechanical and thermal stability. Therefore, around 0.20 g/g of oil in gelatin nanocomposite films can lead to create biodegradable polymers with more acceptable properties for food packaging.

Manufacturing Porous Blocks of Nano-Composite of Needle-Like Hydroxyapatite Crystallites and Chitin for Tissue Engineering

A porous composite scaffold for tissue engineering had been developed through a novel gel-casting approach with needle-like nano hydroxyapatite (HA) crystallites and chitin. The freeze-dried nano-HA powder was firstly dispersed in the chitin solvent before chitin dissolves in its solvent completely. The composite solution was evenly mixed with a selected porosifier and poured into a mold in which it became a composite gel under the reaction of water molecules in atmosphere. Subsequently, the composite gel was subjected to the simultaneous extraction of the porosifier and chitin solvent in distilled water. After the drying process the porous composite scaffold was obtained. The morphological analysis showed that the manufactured scaffold had uniform and isotropic porous structure with controlled, fully interconnected pores. In vitro experiments indicated that the bone-like apatite layer formed easily on the walls of the porous n-HA/chitin composite scaffold.