| 1. |
- Albornoz-Palma, Gregory, et al.
(författare)
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Relationship between rheological and morphological characteristics of cellulose nanofibrils in dilute dispersions
- 2019
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Ingår i: Carbohydrate Polymers. - : Elsevier Ltd. - 0144-8617 .- 1879-1344.
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Tidskriftsartikel (refereegranskat)abstract
- The morphology of cellulose nanofibrils (CNFs), the rheological characteristics of their dispersions, and the corresponding relationships, are fundamental for understanding the properties of the material. This work aims at understanding how the morphological characteristics of the CNFs affect the rheology of the dispersions in the dilute region and to establish a relationship between both properties. A strong relationship was observed between the intrinsic viscosity of the CNF dispersions and their aspect ratio, which can be correlated through the expression ρ[η]=0.051p1.85. When comparing the model obtained in this work to the wormlike chain model, it was possible to verify that these models are independent of the flexibility of the CNFs. Regarding the fibrillation process, the dynamic viscosity only reflects part of the behavior of the morphological properties of the CNFs and does not provide reliable data that would allow these characteristics to be inferred, while the intrinsic viscosity does allow this relationship.
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| 2. |
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| 3. |
- Alexandrescu, Laura C., et al.
(författare)
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Cytotoxicity tests of cellulose nanofibril-based structures
- 2013
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Ingår i: Cellulose. - : Springer Science and Business Media LLC. - 0969-0239 .- 1572-882X. ; 20:4, s. 1765-1775
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Tidskriftsartikel (refereegranskat)abstract
- Cellulose nanofibrils based on wood pulp fibres are most promising for biomedical applications. Bacterial cellulose has been suggested for some medical applications and is presently used as wound dressing. However, cost-efficient processes for mass production of bacterial cellulose are lacking. Hence, fibrillation of cellulose wood fibres is most interesting, as the cellulose nanofibrils can efficiently be produced in large quantities. However, the utilization of cellulose nanofibrils from wood requires a thorough verification of its biocompatibility, especially with fibroblast cells which are important in regenerative tissue and particularly in wound healing. The cellulose nanofibril structures used in this study were based on Eucalyptus and Pinus radiata pulp fibres. The nanofibrillated materials were manufactured using a homogenizer without pre-treatment and with 2,2,6,6-tetramethylpiperidine-1-oxy radical as pre-treatment, thus yielding nanofibrils low and high level of anionic charge, respectively. From these materials, two types of nanofibril-based structures were formed; (1) thin and dense structures and (2) open and porous structures. Cytotoxicity tests were applied on the samples, which demonstrated that the nanofibrils do not exert acute toxic phenomena on the tested fibroblast cells (3T3 cells). The cell membrane, cell mitochondrial activity and the DNA proliferation remained unchanged during the tests, which involved direct and indirect contact between the nano-structured materials and the 3T3 cells. Some samples were modified using the crosslinking agent polyethyleneimine (PEI) or the surfactant cetyl trimethylammonium bromide (CTAB). The sample modified with CTAB showed a clear toxic behaviour, having negative effects on cell survival, viability and proliferation. CTAB is an antimicrobial component, and thus this result was as expected. The sample crosslinked with PEI also had a significant reduction in cell viability indicating a reduction in DNA proliferation. We conclude that the neat cellulose nanostructured materials tested in this study are not toxic against fibroblasts cells. This is most important as nano-structured materials based on nanofibrils from wood pulp fibres are promising as substrate for regenerative medicine and wound healing.
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| 4. |
- Aslan, M., et al.
(författare)
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Strength Variability of Single Flax Fibres
- 2011
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Ingår i: Journal of Materials Science. - : Springer Science and Business Media LLC. - 0022-2461 .- 1573-4803. ; 46
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Tidskriftsartikel (refereegranskat)
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| 5. |
- Brodin, Malin, et al.
(författare)
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Lignocellulosics as sustainable resources for production of bioplastics : a review
- 2017
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Ingår i: Journal of Cleaner Production. - : Elsevier Ltd. - 0959-6526 .- 1879-1786. ; 162, s. 646-664
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Forskningsöversikt (refereegranskat)abstract
- The bio-based economy requires a sustainable utilization of bioresources for production of a range of products, including pulp, paper, chemicals, biofuel and bioplastics. Currently, various types of bioplastics are produced industrially, competing in performance and price with the conventional fossil-oil based plastics. However, there is also a major interest in utilizing non-food crops, such as lignocellulosics, for production of drop-in polymers or new dedicated bioplastics. Lignocellulosic resources have a potential to replace plastics and materials, which have been traditionally based on fossil resources. This is important, as the development of high performance bio-based and renewable materials is one important factor for sustainable growth of the bio-based industry. However, production of bioplastics from forestry biomass requires a dedicated fractionation into the major components, i.e. cellulose, hemicelluloses and lignin, effective purification processes and cost-effective routes for conversion into monomers and platform molecules, utilized as a basis for bioplastics production. These processes are now technologically demanding and not profitable. The intention of this work was thus to review the current advances that have been made during the years within fractionation and purification of lignocelluloses and the processes that may feasible for production of bioplastics, based on wood components.
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| 6. |
- Cano, María Emilia, et al.
(författare)
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Characterization of carboxylated cellulose nanofibrils and oligosaccharides from Kraft pulp fibers and their potential elicitor effect on the gene expression of Capsicum annuum
- 2024
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Ingår i: International Journal of Biological Macromolecules. - : Elsevier B.V.. - 0141-8130 .- 1879-0003. ; 267
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Tidskriftsartikel (refereegranskat)abstract
- Biomass-derived oligo- and polysaccharides may act as elicitors, i.e., bioactive molecules that trigger plant immune responses. This is particularly important to increase the resistance of plants to abiotic and biotic stresses. In this study, cellulose nanofibrils (CNF) gels were obtained by TEMPO-mediated oxidation of unbleached and bleached kraft pulps. The molecular structures were characterized with ESI and MALDI MS. Analysis of the fine sequences was achieved by MS and MS/MS of the water-soluble oligosaccharides obtained by acid hydrolysis of the CNF gels. The analysis revealed the presence of two families: one corresponding to homoglucuronic acid sequences and the other composed by alternating glucose and glucuronic acid units. The CNF gels, alone or with the addition of the water-soluble oligosaccharides, were tested on Chili pepper (Capsicum annuum). Based on the characterization of the gene expression with Next Generation Sequencing (NGS) of the C. annuum’s total messenger RNA, the differences in growth of the C. annuum seeds correlated well with the downregulation of the pathways regulating photosynthesis. A downregulation of the response to abiotic factors was detected, suggesting that these gels would improve the resistance of the C. annuum plants to abiotic stress due to, e.g., water deprivation and cold temperatures.
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| 7. |
- Chinga-Carrasco, Gary, et al.
(författare)
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A method for estimating the fibre length in fibre-PLA composites
- 2013
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Ingår i: Journal of Microscopy. - : Wiley. - 0022-2720 .- 1365-2818. ; 250:1, s. 15-20
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Tidskriftsartikel (refereegranskat)abstract
- Wood pulp fibres are an important component of environmentally sound and renewable fibre-reinforced composite materials. The high aspect ratio of pulp fibres is an essential property with respect to the mechanical properties a given composite material can achieve. The length of pulp fibres is affected by composite processing operations. This thus emphasizes the importance of assessing the pulp fibre length and how this may be affected by a given process for manufacturing composites. In this work a new method for measuring the length distribution of fibres and fibre fragments has been developed. The method is based on; (i) dissolving the composites, (ii) preparing the fibres for image acquisition and (iii) image analysis of the resulting fibre structures. The image analysis part is relatively simple to implement and is based on images acquired with a desktop scanner and a new ImageJ plugin. The quantification of fibre length has demonstrated the fibre shortening effect because of an extrusion process and subsequent injection moulding. Fibres with original lengths of >1 mm where shortened to fibre fragments with length of <200 μm. The shortening seems to be affected by the number of times the fibres have passed through the extruder, the amount of chain extender and the fraction of fibres in the polymer matrix.
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| 8. |
- Chinga-Carrasco, Gary
(författare)
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Advanced biomaterials based on nanofibrillated cellulose : from nanopapers to nanomedicine
- 2014
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Konferensbidrag (refereegranskat)abstract
- Nanofibrillated cellulose (NFC) offers a wide range of interesting opportunities and advantages, being biodegradable, renewable and thus environmentally sound. Extensive research has been performed on the effective production and application of NFC. The proposed applications extend from being a component in paper, coatings and composite materials to being applied in bio-medicine as part of wound dressings or in drug delivery systems. Some of the major advantages of NFC are the dimensions and the structural and chemical composition of nanofibrils, which lead to the formation of dense networks with optimized optical and mechanical properties. In this respect, the concept of nanopaper has been introduced. Nanopapers are strong structures, with high light transmittance and smooth surfaces. These characteristics open for novel applications, including the formation of smooth substrates for printing functionality. A recently explored example is the printing of bioactive biomacromolecules and conductive structures on tailor-made nanopapers, which could form the basis for novel biosensors. Additionally, nanobarriers are most promising in novel packaging applications where the self-assembly properties of the material facilitate the formation of dense structures with high barrier against oxygen. However, NFC alone does not seem to be sufficient for the formation of adequate nanobarriers due to the brittle and hygroscopic characteristics of the material. Novel biocomposite concepts need thus closer attention, where the strong and high barrier properties of NFC could be complemented with adequate bioplastics and additives for the formation of ductile films, suitable for conversion processes. From the biomedical point of view, NFC offers several advantages. Depending on the structural and chemical composition of the material and the cross-linking with adequate polymers and particles, micro-porous and elastic gels can be formed. Such gels can hold a considerable amount of water, thus being an excellent material for keeping a moist environment during wound healing and for facilitating the regeneration process of human tissue. Additionally, NFC gels based on oxidized nanofibrils can have pH-sensitive characteristics, a property with potential in drug delivery. With the intention of giving an extensive description of NFC and its modern applications, this presentation will be divided into three main sections; i) production and definition, ii) characterization including structural, chemical and biological aspects and iii) novel applications of NFC from nanopapers to biomedical devices.
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| 9. |
- Chinga-Carrasco, Gary, et al.
(författare)
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Bagasse—A major agro-industrial residue as potential resource for nanocellulose inks for 3D printing of wound dressing devices
- 2019
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Ingår i: Additive Manufacturing. - : Elsevier B.V.. - 2214-8604 .- 2214-7810. ; 28, s. 267-274
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Tidskriftsartikel (refereegranskat)abstract
- Sugarcane bagasse, an abundant residue, is usually burned as an energy source. However, provided that appropriate and sustainable pulping and fractionation processes are applied, bagasse can be utilized as a main source of cellulose nanofibrils (CNF). We explored in this study the production of CNF inks for 3D printing by direct-ink-writing technology. The CNF were tested against L929 fibroblasts cell line and we confirmed that the CNF from soda bagasse fibers were found not to have a cytotoxic potential. Additionally, we demonstrated that the alginate and Ca 2+ caused significant dimensional changes to the 3D printed constructs. The CNF-alginate grids exhibited a lateral expansion after printing and then shrank due to the cross-linking with the Ca 2+ . The release of Ca 2+ from the CNF and CNF-alginate constructs was quantified thus providing more insight about the CNF as carrier for Ca 2+ . This, combined with 3D printing, offers potential for personalized wound dressing devices, i.e. tailor-made constructs that can be adapted to a specific shape, depending on the characteristics of the wound healing treatment.
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| 10. |
- Chinga-Carrasco, Gary
(författare)
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Biocomposite Inks for 3D Printing
- 2021
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Ingår i: Bioengineering. - : MDPI. - 2306-5354. ; 8:8
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Tidskriftsartikel (övrigt vetenskapligt/konstnärligt)abstract
- Three-dimensional (3D) printing has evolved massively during the last years and is demonstrating its potential in tissue engineering, wound dressings, cell culture models for drug testing, and prosthesis, to name a few [...]
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