| 1. |
- Li, Jingwen, et al.
(författare)
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Emerging Food Packaging Applications of Cellulose Nanocomposites : A Review
- 2022
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 14:19
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Forskningsöversikt (refereegranskat)abstract
- Cellulose is the most abundant biopolymer on Earth, which is synthesized by plants, bacteria, and animals, with source-dependent properties. Cellulose containing beta-1,4-linked D-glucoses further assembles into hierarchical structures in microfibrils, which can be processed to nanocellulose with length or width in the nanoscale after a variety of pretreatments including enzymatic hydrolysis, TEMPO-oxidation, and carboxymethylation. Nanocellulose can be mainly categorized into cellulose nanocrystal (CNC) produced by acid hydrolysis, cellulose nanofibrils (CNF) prepared by refining, homogenization, microfluidization, sonification, ball milling, and the aqueous counter collision (ACC) method, and bacterial cellulose (BC) biosynthesized by the Acetobacter species. Due to nontoxicity, good biodegradability and biocompatibility, high aspect ratio, low thermal expansion coefficient, excellent mechanical strength, and unique optical properties, nanocellulose is utilized to develop various cellulose nanocomposites through solution casting, Layer-by-Layer (LBL) assembly, extrusion, coating, gel-forming, spray drying, electrostatic spinning, adsorption, nanoemulsion, and other techniques, and has been widely used as food packaging material with excellent barrier and mechanical properties, antibacterial activity, and stimuli-responsive performance to improve the food quality and shelf life. Under the driving force of the increasing green food packaging market, nanocellulose production has gradually developed from lab-scale to pilot- or even industrial-scale, mainly in Europe, Africa, and Asia, though developing cost-effective preparation techniques and precisely tuning the physicochemical properties are key to the commercialization. We expect this review to summarise the recent literature in the nanocellulose-based food packaging field and provide the readers with the state-of-the-art of this research area.
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| 2. |
- Li, Jingwen, et al.
(författare)
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Nisin electroadsorption-enabled multifunctional bacterial cellulose membranes for highly efficient removal of organic and microbial pollutants in water
- 2022
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Ingår i: Chemical Engineering Journal. - : Elsevier BV. - 1385-8947 .- 1873-3212. ; 440, s. 135922-
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Tidskriftsartikel (refereegranskat)abstract
- Membranes fabricated from bacteria-produced cellulose have many practical and technological advantages over other means of cellulose fiber production, however, their functionality for targeted applications is limited and requires complex, multi-stage processing, while the mechanisms underpinned the optimum improvements remain largely unknown. Focusing on one of the highest-demand applications in wastewater treatment, here we resolve the three persistent issues in bacterial cellulose membranes (BCMs), namely poor fibrillar network quality, insufficient functionality and unsatisfactory performance, and discover the counterintuitive, yet most effective mechanism of imparting the multifunctional properties. First, innovative application of the Hestrin-Shramm medium instead of the CM0986 medium stimulated Taonella mepensis to produce BCMs with higher yields, more uniform fibrils and developed fibrillar networks, higher crystallinity indexes, better mechanical and thermal properties. Second, a novel but facile electroadsorption method was developed to enhance BCM functionality via bonding a natural bactericidal peptide-Nisin to the deliberately activated terminals on the BCM surface, achieving great antibacterial activity, good durability, well-preserved nanoporous network, outstanding water retention and low toxicity. Third, due to the synergetic effects of surface adsorption, ionic bonding, physical retention and active microbial killing, the Nisin-decorated BCMs enabled outstanding organic dye removal and excellent disinfection performance, among the best in the available reports. Collectively, this study demonstrates that electroadsorption is a promising and potentially generic strategy to fabricate Nisin-decorated and functionalized BCMs for next-generation membrane filters toward water purification.
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| 3. |
- Piao, Xinyue, et al.
(författare)
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Inulin for surimi gel fortification : Performance and molecular weight-dependent effects
- 2023
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Ingår i: Carbohydrate Polymers. - : Elsevier BV. - 0144-8617 .- 1879-1344. ; 305
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Tidskriftsartikel (refereegranskat)abstract
- Inulin is a prebiotic carbohydrate widely used in food industry due to its health benefits and unique rheological properties. For the first time, this study explores the potential of natural inulin as a sustainable food additive to enhance surimi gel characteristics, specifically focusing on understanding its molecular weight effects. The good solubility of inulin facilitates the conversion of alpha-helix to other secondary conformations which are favorable for protein denaturation and aggregation during gelation. Moreover, the abundant -OH groups at the surface of inulin can boost the chemical forces within surimi proteins to reinforce the gel network. Compared to short-chain inulin, long-chain inulin can alleviate proteolysis, enhance hydrophobic interactions and intertwine with myosin molecules, thereby reinforcing the gel network. A more viscous long-chain inulin solution formed within surimi gels fills the space between aggregated proteins and facilitates the lock of water molecules, improving the water -holding capacity (WHC). Thus, an addition of 12 % long-chain inulin leads to an enhanced hardness of surimi gel from 943 to 1593 and improved WHC from 72 % to 85 %. A new inulin-myosin interaction mechanism model is also proposed to provide useful guidelines for surimi processing and expanding the application of inulin within the food industries.
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| 4. |
- Piao, X., et al.
(författare)
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Oxidized cellulose nanofibrils-based surimi gel enhancing additives : Interactions, performance and mechanisms
- 2022
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 133
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Tidskriftsartikel (refereegranskat)abstract
- Surimi-based products with preferred textural properties and high nutritional value are fashionable throughout the market. Enhancing surimi gel characteristics is of key importance for enabling the following processing and warranting the end-product quality, but challenging due to the lack of energy- and performance-efficient processes and the elusive mechanisms underpinned such enhancements. Focusing on enhancing surimi gel properties by introducing sustainable additives, we successfully explore functionalized cellulose nanofibrils as a textural enhancer in surimi gels and establish a new model to expound the interaction mechanisms. Firstly, TEMPO-mediated oxidation prior to homogenization harvests functionalized cellulose nanofibrils with unique fibrillary shape, uniform nano-size, high surface hydrophilicity and activated -COO- groups, highly suited for the additive use in surimi gels (Monto et al., 2021). Secondly, the innovative application of oxidized cellulose nanofibrils at a remarkably low concentrations (0.1 g/100 g surimi) greatly improve the whiteness, microstructure, water holding capacity, gel strength and thermal stability of the surimi gels, through a synergistic effect of matrix-reinforcing, water binding and entrapping, covalent interactions (disulfide bonds, amide bonds), non-covalent interactions (hydrogen bonds, ionic bonds) and favorable protein conformational changes within the network. Next, a new mechanism model toward the high-performance surimi gels is concluded to better elucidate the interactions between oxidized cellulose nanofibrils and myosin molecules. We expect that this work can provide guidelines on designing novel and high-quality cellulose-additive foods and understanding the roles of food additives in meat gel systems, for advancing the applications of new additives and gelation mechanisms in the food industry.
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| 5. |
- Pylypchuk, Ievgen, V, et al.
(författare)
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"Artificial Wood" Lignocellulosic Membranes : Influence of Kraft Lignin on the Properties and Gas Transport in Tunicate-Based Nanocellulose Composites
- 2021
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Ingår i: Membranes. - : MDPI AG. - 2077-0375. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Nanocellulose membranes based on tunicate-derived cellulose nanofibers, starch, and similar to 5% wood-derived lignin were investigated using three different types of lignin. The addition of lignin into cellulose membranes increased the specific surface area (from 5 to similar to 50 m(2)/g), however the fine porous geometry of the nanocellulose with characteristic pores below 10 nm in diameter remained similar for all membranes. The permeation of H-2, CO2, N-2, and O-2 through the membranes was investigated and a characteristic Knudsen diffusion through the membranes was observed at a rate proportional to the inverse of their molecular sizes. Permeability values, however, varied significantly between samples containing different lignins, ranging from several to thousands of barrers (10(-10) cm(3) (STP) cm cm(-2) s(-1) cmHg(-1) cm), and were related to the observed morphology and lignin distribution inside the membranes. Additionally, the addition of similar to 5% lignin resulted in a significant increase in tensile strength from 3 GPa to similar to 6-7 GPa, but did not change thermal properties (glass transition or thermal stability). Overall, the combination of plant-derived lignin as a filler or binder in cellulose-starch composites with a sea-animal derived nanocellulose presents an interesting new approach for the fabrication of membranes from abundant bio-derived materials. Future studies should focus on the optimization of these types of membranes for the selective and fast transport of gases needed for a variety of industrial separation processes.
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| 6. |
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| 7. |
- Quero, Franck, et al.
(författare)
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Top-down Approach to Produce Protein Functionalized and Highly Thermally Stable Cellulose Fibrils
- 2018
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Ingår i: Biomacromolecules. - : AMER CHEMICAL SOC. - 1525-7797 .- 1526-4602. ; 19:8, s. 3549-3559
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Tidskriftsartikel (refereegranskat)abstract
- Protein-functionalized cellulose fibrils, having various amounts of covalently bonded proteins at their surface, were successfully extracted from the tunic of Pyura chilensis tunicates using successive alkaline extractions. Pure cellulose fibrils were also obtained by further bleaching and were used as reference material. Extraction yields of protein-functionalized cellulose fibrils were within the range of 62-76% by weight based on the dry initial tunic powder. Fourier-transform infrared and Raman spectroscopy confirmed the preservation of residual protein at the surface of cellulose fibrils, which was then quantified by X-ray photoelectron spectroscopy. The protein-functionalized cellulose fibrils were found to have relatively high crystallinity and their cellulose I crystalline structure was preserved upon applying alkaline treatments. The extracted cellulosic materials were found to be constituted of fibrils having a ribbon-like morphology with widths ranging from 30 nm up to similar to 400 nm. These protein-functionalized cellulose fibrils were found to have outstanding thermal stability with one of them having onset and peak degradation temperatures of similar to 350 and 374 degrees C, respectively. These values were found to be 24 and 41 degrees C higher than for bleached cellulose.
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| 8. |
- Tagami, Ayumu, et al.
(författare)
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Lignin-modified tunicate cellulose nanofiber (CNF)-starch composites: impact of lignin diversity on film performance
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Annan publikation (övrigt vetenskapligt/konstnärligt)abstract
- Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF) - starch mixture to prepare 100% bio-based composite films. The aim was to investigate the correlation between lignin diversity and film performance. It was confirmed that lignin’s distribution in the films was dependent on the solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The -OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to the thermal stability decrease and the Young's modulus increase of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic -OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol contents, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the positive relationship between the antioxidant ability of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin’s applications in bio-based materials based on their specific characteristics.
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| 9. |
- Wang, Miao, et al.
(författare)
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From hollow lignin microsphere preparation to simultaneous preparation of urea encapsulation for controlled release using industrial kraft lignin via slow and exhaustive acetone-water evaporation
- 2020
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Ingår i: Holzforschung. - : De Gruyter. - 0018-3830 .- 1437-434X. ; 74:1, s. 77-87
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Tidskriftsartikel (refereegranskat)abstract
- Lignin nano/microparticles have recently attracted growing interest for various value-additive applications of lignin, especially encapsulation. In this study, in order to establish a highly efficient and highly productive preparation process to effectively utilize technical lignin, a brand-new, slow and exhaustive solution evaporation process following a simple, self-assembly principle was developed using industrial softwood kraft lignin (SKL) from a starting acetone-water (80/20, v/v) solution to recover 100% of the lignin as homogeneous and well-shaped microspheres. The prepared microspheres had a typical average diameter of 0.81 ± 0.15 μm and were hollow with very thin shells (of nanoscale thickness). Based on this developed technique, encapsulation of urea by these lignin microspheres was directly achieved using the same process as hollow lignin microspheres with urea attached to the outside and entrapped inside of the wall. Two distinct urea release rates were observed for the urea-encapsulated microspheres: a fast release of the urea outside the shell wall and a slow (controlled) release of the urea inside the shell wall. The encapsulation efficiency was as high as 46% of the trapped urea as encapsulated inside the lignin microspheres. The slow and exhaustive solution evaporation procedure reported here is a simple and straightforward method for the valorization of industrial kraft lignin as hollow microspheres with controllable, homogeneous and desired morphologies, and especially for the direct preparation of lignin-based encapsulating fertilizers for controlled release.
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| 10. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Cellulose nanofibrils-stabilized food-grade Pickering emulsions : Clarifying surface charge's contribution and advancing stabilization mechanism understanding
- 2024
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 152
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Tidskriftsartikel (refereegranskat)abstract
- Pickering emulsions stabilized by cellulose nanofibrils (CN) have sparked significant attention, however the fundamental mechanisms underpinning the stabilization process remain insufficiently elucidated. Focusing on an academic debate of surface charge's contribution to stabilization, this study first explored how the varying carboxyl group contents of TEMPO-oxidized CN (TCNs) impacted Pickering emulsions' formation and stability. TCNs with 662 μmol/g carboxyl groups exhibited distinctive attributes, including larger particle sizes (322 nm in length), improved thermal stability (maximum decomposition temperature of 317 °C), and increased viscosity (1.57 Paִִ⋅s) compared to their counterparts with 963–1011 μmol/g charge density. Notably, the former one, with a larger three-phase contact angle (51.5°), higher interfacial tension, and greater detachment energy (21.69 × 10−18 J), resulted in a homogeneous dispersion of spherical oil droplets and super-stable Pickering emulsions with a consistent emulsifying index of 100% over 30 days. These findings clearly clarified that TCNs with a lower charge density exhibit superior emulsifying properties. In addition, for the first time, a distinct oil droplet-decorated fibrillar structure was observed, probably suggesting that TCNs might be able to serve as anchoring matrixes to guide the distribution of oil droplets. These structures seemed to impeded the migration and accumulation of the oil droplets, consequently enhancing the stability of the resulting Pickering emulsions. To sum, this study clearly elucidated the role of surface charge in stabilizing cellulose-based Pickering emulsions and proposed a new model to expound the cellulose-oil interaction mechanisms, thus providing new theoretical and practical insights on utilization of CN as highly effective emulsifier for super-stable food-grade Pickering emulsions.
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| 11. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Collagens for surimi gel fortification : Type-dependent effects and the difference between type I and type II
- 2023
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Ingår i: Food Chemistry. - : Elsevier BV. - 0308-8146 .- 1873-7072. ; 407, s. 135157-
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Tidskriftsartikel (refereegranskat)abstract
- Surimi products have unsatisfactory gel properties. Hence, this study evaluates the effect of collagen-adding on surimi gel properties and provides the first observation results regarding collagen type influence. With higher water solubility and more charged amino acids than type II, collagen type I intertwines with surimi myofibrillar proteins better to induce higher exposure of protein functional domains, more sufficient conformational changes of myosin and greater formation of chemical forces among proteins. These enhancements accelerate the gelation rate, leading to a well-stabilized surimi gel. The collagen I-containing surimi gels show more compact structures with uniformly distributed smaller pores than those containing collagen II, thereby providing the final products with higher water holding capacity and better textural profiles. As such, the surimi gel fortification performance of collagen I and the well-elucidated collagen-myofibrillar protein interaction mechanism will guide the further exploitation of collagen as an effective additive in the food industry.
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| 12. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Enhancement of myofibrillar protein gelation by plant proteins for improved surimi gel characteristics: Mechanisms and performance
- 2024
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Ingår i: Lebensmittel-Wissenschaft + Technologie. - : Elsevier BV. - 0023-6438 .- 1096-1127. ; 198
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Tidskriftsartikel (refereegranskat)abstract
- Three commonly used plant proteins, soy isolate protein (SPI), wheat gluten (WG) and pea protein (PP), were incorporated into surimi gels, and their effects on myofibrillar protein gelation and resultant surimi gel properties have been investigated. Results revealed that addition of any of these plant proteins at 5 g/100 g surimi enhanced the surimi gelation, among which SPI addition resulted in smoother, denser and whiter surimi gels (whiteness of 61.49) with superior textural attributes (hardness of 1994 g), water-holding capacity (85.67%) and structural integrity. Such improvements were attributed to the uniform distribution of SPI solution between adjacent surimi protein molecules, not only aiding in maintaining the matrix's continuity but bridging the interaction between the proteins. SPI with a higher content of charged amino acids (47.17%) exhibited a better ability to interact with the charged N- and C- terminals of surimi proteins. This interaction promoted the complete unfolding of surimi proteins, facilitated the conversion of α-helix to β structures, exposing hydrophobic ends and sulfhydryl groups, and consequently enhanced the formation of hydrophobic interactions and disulfide bonds during gelation. This study demonstrated that plant proteins, especially SPI, are effective gel-reinforcing additives in surimi gels, offering insights for developing plant protein-rich surimi products.
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| 13. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Enhancement of surimi gel properties through the synergetic effect of fucoidan and oligochitosan
- 2023
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Ingår i: Food Hydrocolloids. - : Elsevier BV. - 0268-005X .- 1873-7137. ; 140
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Tidskriftsartikel (refereegranskat)abstract
- For the first time, two common marine-derived dietary fibres (MDFs), fucoidan (FU) and oligochitosan (OCS), were introduced as textural and nutritional enhancers in hairtail surimi gels. The MDFs could assist with inhabiting the endogenous proteolytic enzyme activity, unfolding the myosin to expose more reactive domains, inducing favorable protein conformational transition, and thus, promoting gelation. The highly hydrophilic MDFs rich in -OH groups can bind water molecules via strong hydrogen bonds, facilitating water redistribution within the gel network. Driven by the enhanced chemical forces, a stable protein-FU-OCS gel is obtained, which improves the hardness by almost 100% and the water holding capacity from 86.25% to 92.25%. Collectively, this study demonstrates that MDFs are a group of effective additives to improve gel characteristics and nutritional profiles of surimi-based seafood products. The proposed MDF-protein interaction model would guide the application of MDFs as novel additives in the food industry.
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| 14. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Fabrication of multidimensional bio-nanomaterials from nanocellulose oxalate
- 2023
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Ingår i: Cellulose. - : Springer Nature. - 0969-0239 .- 1572-882X. ; 30:4, s. 2147-2163
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Tidskriftsartikel (refereegranskat)abstract
- Nanocelluloses and cellulose nanomaterials derived from natural resources are a group of ideal platform materials for advanced applications. However, their synthesis through sustainable and facile processes to achieve the required properties are still challenging. Here, we prepare the nanocellulose oxalate (n-COX) from cotton with outstanding physicochemical properties by defining the optimal oxalic acid pretreatment conditions. Thus-obtained n-COX with unique 1D nanofiber shape as a platform material is further processed to various high-performance multidimensional bio-nanomaterials through several simple yet effective strategies. First, 2D n-COX films prepared through a casting-drying method show comparable or even better transparency and tensile strength than those made from other types of nanocelluloses. Second, 3D n-COX hydrogels/aerogels fabricated by a molding-crosslinking approach demonstrate good shape stability, well-preserved nanoporous networks, and qualified mechanical properties. Third, n-COX-derived bioinks display improved printability and fidelity, resulting in better size-preserving and shape-control of the 3D-bioprinted scaffolds. We expect this work could offer new insights on engineering natural cellulose and using n-COX as a platform material for further advanced fabrication, and thus, open up application potentials of this new nanocellulose.
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| 15. |
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| 16. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Mechanically Reinforced, Flexible, Hydrophobic and UV Impermeable Starch-Cellulose Nanofibers (CNF)-Lignin Composites with Good Barrier and Thermal Properties
- 2021
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Ingår i: Polymers. - : MDPI AG. - 2073-4360. ; 13:24, s. 4346-
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Tidskriftsartikel (refereegranskat)abstract
- Bio-based composite films have been widely studied as potential substitutes for conventional plastics in food packaging. The aim of this study was to develop multifunctional composite films by introducing cellulose nanofibers (CNF) and lignin into starch-based films. Instead of costly and complicated chemical modification or covalent coupling, this study optimized the performance of the composite films by simply tuning the formulation. We found that starch films were mechanically reinforced by CNF, with lignin dispersing as nanoparticles embedded in the matrix. The newly built-up hydrogen bonding between these three components improves the integration of the films, while the introduction of CNF and lignin improved the thermal stability of the starch-based films. Lignin, as a functional additive, improved hydrophobicity and blocked UV transmission. The inherent barrier property of CNF and the dense starch matrix provided the composite films with good gas barrier properties. The prepared flexible films were optically transparent, and exhibited UV blocking ability, good oxygen-barrier properties, high hydrophobicity, appreciable mechanical strength and good thermal stability. These characteristics indicate potential utilization as a green alternative to synthetic plastics especially for food packaging applications.
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| 17. |
- Zhao, Yadong, 1985-, et al.
(författare)
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The Impact of Lignin Structural Diversity on Performance of Cellulose Nanofiber (CNF)-Starch Composite Films
- 2019
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Ingår i: Polymers. - : MDPI. - 2073-4360. ; 11:3
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Tidskriftsartikel (refereegranskat)abstract
- Lignin fractions having different molecular weights and varied chemical structures isolated from kraft lignins of both softwood and hardwood via a sequential solvent fractionation technique were incorporated into a tunicate cellulose nanofibers (CNF)-starch mixture to prepare 100% bio-based composite films. The aim was to investigate the impact of lignin structural diversity on film performance. It was confirmed that lignin's distribution in the films was dependent on the polarity of solvents used for fractionation (acetone > methanol > ethanol > ethyl acetate) and influenced the optical properties of the films. The -OH group content and molecular weight of lignin were positively related to film density. In general, the addition of lignin fractions led to decrease in thermal stability and increase in Young's modulus of the composite films. The modulus of the films was found to decrease as the molecular weight of lignin increased, and a higher amount of carboxyl and phenolic -OH groups in the lignin fraction resulted in films with higher stiffness. The thermal analysis showed higher char content formation for lignin-containing films in a nitrogen atmosphere with increased molecular weight. In an oxygen atmosphere, the phenol content, saturated side chains and short chain structures of lignin had impacts on the maximum decomposition temperature of the films, confirming the relationship between the chemical structure of lignin and thermo-oxidative stability of the corresponding film. This study addresses the importance of lignin diversities on composite film performance, which could be helpful for tailoring lignin's applications in bio-based materials based on their specific characteristics.
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| 18. |
- Zhao, Yadong, 1985-
(författare)
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Towards Large-scale and Feasible Exploitation of Tunicate Cellulose and Cellulose Nanocrystals for Different Applications
- 2015
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Tunicates are a group of filter-feeding animals that live in the ocean. They are widely distributed throughout the world and are a major contributor to the fouling problem in aquaculture. In addition to their natural abundance, large-scale farming will further render them readily available in high quantities, and they should instead be providing us food, energy, chemicals and materials. As tunicates are the sole known animal group synthesizing cellulose, the primary target for this bioresources exploitation should be cellulose preparation and application. Moreover, cellulose exploitation should be conducted in both a technically and economically feasible manner.Among the tunicates, Ciona intestinalis (termed Ciona hereafter) is one of the most abundant species in Norwegian and Swedish coastal waters. Upon comprehensive quantification of the principal chemical compositions, cellulose has been confirmed to exist as cellulose-protein fibrils cemented by non-cellulose glycans and lipids and is almost exclusively present in the Ciona tunic fraction. Using the tunic as raw material, Ciona cellulose was prepared following a unique prehydrolysis-kraft cooking-bleaching sequence with a yield of 21.64% and by a modified Updegraff method with a yield of 23.65% on a dried ash-free mass basis. To improve the Ciona cellulose dispersibility and processability, Ciona cellulose nanocrystals (CNs) were prepared using different processes, namely acid hydrolysis, 2,2,6,6‑tetramethylpiperidine-1-oxyl (TEMPO)-mediated oxidation and enzymatic hydrolysis as well as acid hydrolysis followed by TEMPO-mediated oxidation. The CN preparation yield was 30.0-73.4%, depending on the process applied.By conducting comprehensive characterizations, it was found that the Ciona cellulose was nearly 100% pure, with a large weight average degree of polymerization (DPw=4200), a high surface area (133 m2/g), a large aspect ratio (length of several micrometres and diameter of ~16 nm), a high crystallinity (89%) in the form of nearly pure Iβ crystals, and a good thermal stability (onset degradation temperature of 226 ºC). When obtained in membrane form, the cellulose preserved the native interwoven microfibril network structure in the original tunic. It had a high ductility (tensile strain of 19.24%) in the wet state and good mechanical strength (tensile strength of 41.19 MPa and Young’s Modulus of 1.98 GPa) when dried. The CNs obtained were smaller in DPw, shorter in morphological size (length), similar or higher in crystallinity and more thermally stable than the starting cellulose to different extents and with different charged structures and charge contents dependent on the method/procedure used.Several applications have been examined. First, the Ciona cellulose in pulp form was utilized in the fabrication of sponge cloth to replace cotton, and the product obtained was of similar quality to the commercial one made from cotton. Second, the Ciona cellulose in membrane form was tested in the cultivation of human umbilical vein endothelial cells and mouse NIH‑3T3 cells for evaluations of cell proliferation performance and medical application potential. The performance was very positive. Third, the Ciona cellulose membrane and two CNs were applied as the matrix for high-quality zinc-blende CdSe/CdS core/shell nanocrystal quantum dots (QDs) for the development of mechanically strong and high-performance fluorescent material. The QDs were firmly attached to the Ciona CNs with uniform monolayer distribution and a high packing density. The obtained composites preserved both the high-quality optical properties from the QDs and the matrix morphology and thus expectedly the excellent mechanical properties from the cellulose. Finally, the Ciona CNs were processed to composite films cemented by konjac glucomannan for material development. Newly introduced hydrogen bonds between these two compatible polysaccharides and thus strong cementing effects were observed. The composite films showed excellent mechanical properties in addition to improved transparency, thermal stability and hydrophobicity compared with the CN’s neat films.Feasible tunicate cellulose exploitation demands the sound large-scale farming of Ciona for the highest possible cellulose content in the farmed animal, the exploitation of species other than Ciona, the complete utilization of fractions other than the tunic used and the value-added productions of other by-products. Composition quantification of the adult Ciona specimens collected from different farms showed that the carbohydrate content was linearly correlated with the body weight, which in turn was affected by the farm location, deployment time and sub-sea depth of the settling structures. Through analysing the Ciona intestinal content, it was found that both eukaryotes and prokaryotes contributed to the diet of the animal, and their quantities were positively correlated with the animal size (body weight). The tunics of three other tunicate species, Halocynthia roretzi, Styela plicata, and Ascidia sp., have been examined for tunicate cellulose preparation following the prehydrolysis-kraft cooking‑bleaching procedure. They were all found to be good sources for similar quality tunicate cellulose exploitation, thus verifying the universal applicability of the procedure. Based on more detailed chemical composition analyses, all the fractions other than the tunic, termed the inner body tissues fraction, from all four tunicate species were found to have excellent nutritional values: a high protein content with good quality amino acids and high contents of omega-3 (n-3) fatty acids and essential elements. Their toxic element contents were under the regulated limits for human food. They should therefore all be explored as human food sources. Furthermore, many different chemical structures, many of which were found for the first time, were present in the tunicate animals studied, ranging from collagens, glycosaminoglycans, and sterols to phospholipids. These structures should be explored as various bioactive by‑products during tunicate cellulose exploitation. For example, the prepared Ciona lipids had a high content of n-3 fatty acids, which presented mainly in the form of phospholipids. They should be an excellent alternative to markedly high value fish oils, but with a higher bioavailability.The techniques and knowledge obtained by this study will provide a basis for the promising large-scale and feasible exploitation of tunicate cellulose and cellulose nanocrystals for different applications.
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| 19. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Transparent Composites Made from Tunicate Cellulose Membranes and Environmentally Friendly Polyester
- 2018
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Ingår i: ChemSusChem. - : WILEY-V C H VERLAG GMBH. - 1864-5631 .- 1864-564X. ; 11:10, s. 1728-1735
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Tidskriftsartikel (refereegranskat)abstract
- A series of optically transparent composites were made by using tunicate cellulose membranes, in which the naturally organized cellulose microfibrillar network structure of tunicate tunics was preserved and used as the template and a solution of glycerol and citric acid at different molar ratios was used as the matrix. Polymerization through ester bond formation occurred at elevated temperatures without any catalyst, and water was released as the only byproduct. The obtained composites had a uniform and dense structure. Thus, the produced glycerol citrate polyester improved the transparency of the tunicate cellulose membrane while the cellulose membrane provided rigidity and strength to the prepared composite. The interaction between cellulose and polyester afforded the composites high thermal stability. Additionally, the composites were optically transparent and their shape, strength, and flexibility were adjustable by varying the formulation and reaction conditions. These composites of cellulose, glycerol, and citric acid are renewable and biocompatible and have many potential applications as structural materials in packaging, flexible displays, and solar cells.
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| 20. |
- Zhao, Yadong, 1985-, et al.
(författare)
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Unique and outstanding quantum dots (QD)/tunicate cellulose nanofibrils (TCNF) nanohybrid platform material for use as 1D ink and 2D film
- 2020
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344. ; 242
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Tidskriftsartikel (refereegranskat)abstract
- Quantum dots (QD)/polymer materials have wide applications in biological imaging, clinical diagnostics, anti-counterfeiting materials, light-emitting devices and solar cells. The development of QD/cellulose nanofibrils (CNF) hybrids with a more perfect structure and excellent properties is important for improving known applications. A unique tunicate CNF (TCNF) was homogeneously blended with outstanding CdSe/CdS core/shell QD to prepare a novel QD/TCNF hybrid. The QD were monodispersed on a single TCNF fibril surface as an evenly distributed monolayer with an extremely high packing density and no visible aggregation. The prepared hybrid is an excellent platform nanomaterial which was demonstrated by its good writing fidelity when applied as a 1D ink and by its good processability in the preparation of 2D films with acceptable transparency and flexibility. This one-step direct blending approach provides a facile shortcut to effectively fabricate cellulose-based high-performance functional QD nanomaterials at the single-fibril level.
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