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  • 1.
    Albornoz-Palma, Gregory
    et al.
    Universidad de Concepción, Chile.
    Betancourt, Fernando
    Universidad de Concepción, Chile.
    Mendonça, Regis
    Universidad de Concepción, Chile.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Pereira, Miguel
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. Universidad de Concepción, Chile.
    Relationship between rheological and morphological characteristics of cellulose nanofibrils in dilute dispersions2019In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, article id 115588Article in journal (Refereed)
    Abstract [en]

    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. 

  • 2. Alexandrescu, L.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Iotti, M.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Gregersen, Ø.
    Belosi, F.
    Gatti, A.M.
    Air filtration of nano-particles using cellulose nanofibrils2012Conference paper (Refereed)
  • 3.
    Alexandrescu, Laura C.
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Gatti, Antonietta Maria
    ISTEC-CNR, Italy.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cytotoxicity tests of cellulose nanofibril-based structures2013In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 20, no 4, p. 1765-1775Article in journal (Refereed)
    Abstract [en]

    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.

  • 4. Aslan, M.
    et al.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Sørensen, B.F.
    Madsen, B.
    Strength Variability of Single Flax Fibres2011In: Journal of Materials Science, ISSN 0022-2461, E-ISSN 1573-4803, Vol. 46Article in journal (Refereed)
  • 5.
    Brodin, Malin
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Vallejos, Maria
    Instituto de Materiales de Misiones (IMAM), Argentina.
    Opedal, Mihaela Tanase
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Area, Maria C.
    Instituto de Materiales de Misiones (IMAM), Argentina.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Lignocellulosics as sustainable resources for production of bioplastics: a review2017In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 162, p. 646-664Article, review/survey (Refereed)
    Abstract [en]

    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.

  • 6.
    Chinga Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Pasquier, Eva
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Solberg, Amalie
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Leirset, Ingebjørg
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Stevanic Srndovic, Jasna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Rosendahl, Jennifer
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Håkansson, Joakim
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology. University of Gothenburg, Sweden.
    Carboxylated nanocellulose for wound healing applications – Increase of washing efficiency after chemical pre-treatment and stability of homogenized gels over 10 months2023In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 314, article id 120923Article in journal (Refereed)
    Abstract [en]

    To commercialize a biomedical product as a medical device, reproducibility of production and time-stability are important parameters. Studies of reproducibility are lacking in the literature. Additionally, chemical pre-treatments of wood fibres to produce highly fibrillated cellulose nanofibrils (CNF) seem to be demanding in terms of production efficiency, being a bottleneck for industrial upscaling. In this study, we evaluated the effect of pH on the dewatering time and washing steps of 2,2,6,6-Tetramethylpiperidinyloxy (TEMPO)-mediated oxidized wood fibres when applying 3.8 mmol NaClO/g cellulose. The results indicate that the method does not affect the carboxylation of the nanocelluloses, and levels of approximately 1390 μmol/g were obtained with good reproducibility. The washing time of a Low-pH sample was reduced to 1/5 of the time required for washing a Control sample. Additionally, the stability of the CNF samples was assessed over 10 months and changes were quantified, the most pronounced were the increase of potential residual fibre aggregates, reduction of viscosity and increase of carboxylic acid content. The cytotoxicity and skin irritation potential were not affected by the detected differences between the Control and Low-pH samples. Importantly, the antibacterial effect of the carboxylated CNFs against S. aureus and P. aeruginosa was confirmed. © 2023 The Authors

  • 7.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Advanced biomaterials based on nanofibrillated cellulose: from nanopapers to nanomedicine2014Conference paper (Refereed)
    Abstract [en]

    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.

  • 8.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Biocomposite Inks for 3D Printing2021In: Bioengineering, E-ISSN 2306-5354, Vol. 8, no 8, article id 102Article in journal (Other academic)
    Abstract [en]

    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 [...]

  • 9.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose fibres, nanofibrils and microfibrils: The morphological sequence of MFC components from a plant physiology and fibre technology point of view2011In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 6Article in journal (Refereed)
  • 10.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Complementary microscopy techniques for surface characterisation of uncoated and mineral pigment coated paper2012In: Current microscopy contributions to advances in science and technology / [ed] Méndez-Vilsa A., Formatex Research Center, 2012, p. 1448-1455Chapter in book (Refereed)
  • 11.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Complementary Microscopy Techniques for Surface Characterisation of Uncoated and Mineral Pigment Coated Paper2012In: Current Microscopy Contributions to Advances in Science and Technology, Formatex Research Center , 2012, , p. 8Chapter in book (Refereed)
  • 12.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Microscopy and computerized image analysis of wood pulp fibres multiscale structures2010In: Microscopy: Science, technology, applications and education / [ed] Méndez-Vilas A., Formatex Research Center, 2010, p. 2182-2189Chapter in book (Refereed)
  • 13.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Novel biocomposite engineering and bio-applications2018In: Bioengineering, ISSN 2306-5354, Vol. 5, no 4, p. 80-Article in journal (Other academic)
  • 14.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Optical methods for the quantification of the fibrillation degree of bleached MFC materials2013In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 48, p. 42-48Article in journal (Refereed)
    Abstract [en]

    In this study, the suitability of optical devices for quantification of the fibrillation degree of bleached microfibrillated cellulose (MFC) materials has been assessed. The techniques for optical assessment include optical scanner, UV-vis spectrophotometry, turbidity, quantification of the fiber fraction and a camera system for dynamic measurements. The results show that the assessed optical devices are most adequate for quantification of the light transmittance of bleached MFC materials. Such quantification yields an estimation of the fibrillation degree. Films made of poorly fibrillated materials are opaque, while films made of highly fibrillated materials containing a major fraction of nanofibrils are translucent, with light transmittance larger than 90%. Finally, the concept of using images acquired with a CCD camera system, for estimating the fibrillation degree in dynamic conditions was exemplified. Such systems are most interesting as this will widen the applicability of optical methods for quantification of fibrillation degree online in production lines, which is expected to appear in the years to come.

  • 15.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Por una ciencia integrada2018In: Celulosa Y Papel, ISSN 0716-2308, Vol. 34, no 4, p. 12-15Article in journal (Other academic)
  • 16.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Potential and Limitations of Nanocelluloses as Components in Biocomposite Inks for Three-Dimensional Bioprinting and for Biomedical Devices.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 701-711Article in journal (Refereed)
    Abstract [en]

    Three-dimensional (3D) printing has rapidly emerged as a new technology with a wide range of applications that includes biomedicine. Some common 3D printing methods are based on the suitability of biopolymers to be extruded through a nozzle to construct a 3D structure layer by layer. Nanocelluloses with specific rheological characteristics are suitable components to form inks for 3D printing. This review considers various nanocelluloses that have been proposed for 3D printing with a focus on the potential advantages, limitations, and requirements when used for biomedical devices and when used in contact with the human body.

  • 17.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Aasrød, Kenneth
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Leinsvang, Berit
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bouveng, Mikael
    RISE, Innventia.
    Johansson, Per-Åke
    RISE, Innventia.
    Structural effects on print-through and set-off2012In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 27, no 3, p. 596-603Article in journal (Refereed)
    Abstract [en]

    In this study the effect of paper structure on ink transfer and cold-set print quality was assessed. A factorial experiment involving 5 factors with two levels was designed. Several sheet structures were constructed. The sheets were made from three basic pulps, thermomechanical pulp (TMP), de-inked pulp (DIP) and stone groundwood (SGW). The designed structures were homogeneous and layered to verify the effect of sheet structure and fines content on print quality. A comprehensive multiscale characterisation of the sheet structures was performed. The analyses comprised scanning electron microscopy (SEM) and mercury porosimetry for bulk structure assessment. Parker Print Surf (PPS), laser profilometry and field-emission scanning electron microscopy (FE-SEM) were applied for giving a detailed description of the surface structure affecting ink transfer. The study revealed that the surface structure affects the ink demand and set-off. Increasing the micro-roughness leads to an increment of ink demand in order to achieve a given print density. The bulk pore structure affects the light scattering coefficients. Small pores are positive for increasing the light scattering and thus for reducing the print-through level. This was confirmed by SEM and mercury porosimetry measurements.

  • 18.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Gibadullin, Marat R.
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Micro-structural characterisation of homogeneous and layered MFC nano-composites2013In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 44, no 1, p. 331-338Article in journal (Refereed)
    Abstract [en]

    The complementary capabilities of various characterisation methods for micro-structural assessment are demonstrated. The assessed structures were composed of unbleached microfibrillated cellulose (MFC) in combination with bleached and 2,2,6,6-tetramethylpiperidinyl-1-oxyl (TEMPO) pre-treated MFC materials. The biodegradable nano-composites were thus characterised in detail, including laser profilometry, scanning electron microscopy (SEM) in high and low vacuum modes, and field-emission SEM. The distribution of the unbleached MFC materials was assessed by staining the unbleached MFC with osmium tetroxide (OsO4), which reacts with CC double bonds encountered in lignin. In addition, some properties of the MFC nano-composite films were tested, i.e. tensile properties, water wettability and oxygen permeability. In general, the group of characteristics of the nano-composite MFC films was better than the properties of the films made of the neat MFC qualities. This indicates that mixing complementary MFC qualities could give synergetic effects that are not exploited completely when using the MFC qualities separately. The study thus confirms the suitability of unbleached MFC materials as a component in multilayer structures, for example biodegradable packaging applications.

  • 19.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Averianova, Natalia V.
    Kazan National Research Technological University, Russia.
    Kondalenko, Olga
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Petrov, Vladimir A.
    Kazan National Research Technological University, Russia.
    Leinsvang, Berit
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of residual fibres on the micro-topography of cellulose nanopaper2014In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 56, p. 80-84Article in journal (Refereed)
    Abstract [en]

    Nanopaper is a new material concept composed of nanocellulose, which has been proposed for a series of applications. Recently, the surface of nanopapers has also been emphasized as an important structure to control. This is due to the potential of nanopaper structures as a substrate for printing functionality, which could expand the applicability of nanopaper as a functionalized biomaterial. In this study, we demonstrate how the roughness of nanopaper is affected by the fraction of residual fibres that were not fibrillated into nanofibrils after a homogenization procedure. The topography and morphology were assessed with laser profilometry, atomic force microscopy and scanning (transmission) electron microscopy. The results show a linear correlation between the estimated fraction of residual fibres and the roughness of the assessed nanopapers. Furthermore, the fraction of residual fibres can be reduced by fractionating the nanocellulose, which is demonstrated in the present work. Such knowledge will be valuable for designing nanopaper surfaces with specific structural characteristics.

  • 20.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Brodin, Malin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Karlsen, Trond
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Wood pulp fibres and nanocellulose: Characterization and application in biocomposite materials2014Conference paper (Refereed)
    Abstract [en]

    A composite can be defined as a material composed of two or more components having distinct morphology and chemistry, and giving synergetic effects. In this paper the term biocomposite is used, referring to i) a material having at least one bio-component (e.g. wood pulp fibres and nanofibrils) or ii) biomaterials intended for biomedical applications. The utilization of wood pulp fibres in composite materials has gained major interest during the last years. There are various wood pulp fibres that can be used as reinforcement in composites, e.g. thermo-mechanical pulp (TMP), chemi-thermo-mechanical pulp (CTMP) and kraft pulp fibres. Depending on the pulping process (TMP, CTMP or kraft pulp), the pulp fibres differ greatly with respect to the fibre morphology and chemistry. Kraft pulp fibres have been one of the most used raw materials for producing nanocellulose. Nanocellulose from wood refers to various cellulose nano-materials such as cellulose nanocrystals and nanofibrillated cellulose. Nanofibrillated cellulose is composed of a major fraction of structurally homogeneous nanofibrils having typical widths in the nanometre scale and lengths in the micrometre scale. Wood pulp fibres and nanofibrils have been proposed as reinforcement in composite materials. Some of the major motivations have been the potential improvements by using fibres and nanofibrillated materials with respect to e.g. strength, biodegradability and functionality. The purpose of the present work is to review some advances in biocomposite research and development, including three focus areas; structured biocomposites, flexible biocomposites and biomaterials.

  • 21.
    Chinga-Carrasco, Gary
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Ehman, Nanci
    IMAM, Argentina.
    Filgueira, Daniel
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Johansson, Jenny
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Vallejos, Maria
    IMAM, Argentina.
    Felissia, Fernando
    IMAM, Argentina.
    Håkansson, Joakim
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Area, Maria
    IMAM, Argentina.
    Bagasse—A major agro-industrial residue as potential resource for nanocellulose inks for 3D printing of wound dressing devices2019In: Additive Manufacturing, ISSN 2214-8604, E-ISSN 2214-7810, Vol. 28, p. 267-274Article in journal (Refereed)
    Abstract [en]

    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.

  • 22.
    Chinga-Carrasco, Gary
    et al.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Ehman, Nanci V.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Pettersson, Jennifer
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Vallejos, Maria E.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Brodin, Malin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Felissia, Fernando E.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Håkansson, Joakim
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Area, Maria C.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Pulping and Pretreatment Affect the Characteristics of Bagasse Inks for Three-dimensional Printing2018In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 6, no 3, p. 4068-4075Article in journal (Refereed)
    Abstract [en]

    Bagasse is an underutilized agro-industrial residue with great potential as raw material for the production of cellulose nanofibrils (CNF) for a range of applications. In this study, we have assessed the suitability of bagasse for production of CNF for three-dimensional (3D) printing. First, pulp fibers were obtained from the bagasse raw material using two fractionation methods, i.e. soda and hydrothermal treatment combined with soda. Second, the pulp fibers were pretreated by TEMPO-mediated oxidation using two levels of oxidation for comparison purposes. Finally, the CNF were characterized in detail and assessed as inks for 3D printing. The results show that CNF produced from fibers obtained by hydrothermal and soda pulping were less nanofibrillated than the corresponding material produced by soda pulping. However, the CNF sample obtained from soda pulp was cytotoxic, apparently due to a larger content of silica particles. All the CNF materials were 3D printable. We conclude that the noncytotoxic CNF produced from hydrothermally and soda treated pulp can potentially be used as inks for 3D printing of biomedical devices. 

  • 23.
    Chinga-Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Johansson, Jenny
    RISE Research Institutes of Sweden, Materials and Production.
    Heggset, Ellinor B
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Leirset, Ingebjørg
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Björn, Camilla
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Agrenius, Karin
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles.
    Stevanic Srndovic, Jasna
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Håkansson, Joakim
    RISE Research Institutes of Sweden, Materials and Production, Chemistry, Biomaterials and Textiles. Gothenburg University, Sweden.
    Characterization and Antibacterial Properties of Autoclaved Carboxylated Wood Nanocellulose.2021In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 22, no 7, p. 2779-2789Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) were obtained by applying a chemical pretreatment consisting of autoclaving the pulp fibers in sodium hydroxide, combined with 2,2,6,6-tetramethylpiperidinyl-1-oxyl-mediated oxidation. Three levels of sodium hypochlorite were applied (2.5, 3.8, and 6.0 mmol/g) to obtain CNF qualities (CNF_2.5, CNF_3.8, and CNF_6.0) with varying content of carboxyl groups, that is, 1036, 1285, and 1593 μmol/g cellulose. The cytotoxicity and skin irritation potential (indirect tests) of the CNFs were determined according to standardized in vitro testing for medical devices. We here demonstrate that autoclaving (121 °C, 20 min), which was used to sterilize the gels, caused a modification of the CNF characteristics. This was confirmed by a reduction in the viscosity of the gels, a morphological change of the nanofibrils, by an increase of the ultraviolet-visible absorbance maxima at 250 nm, reduction of the absolute zeta potential, and by an increase in aldehyde content and reducing sugars after autoclaving. Fourier-transform infrared spectroscopy and wide-angle X-ray scattering complemented an extensive characterization of the CNF gels, before and after autoclaving. The antibacterial properties of autoclaved carboxylated CNFs were demonstrated in vitro (bacterial survival and swimming assays) on Pseudomonas aeruginosa and Staphylococcus aureus. Importantly, a mouse in vivo surgical-site infection model on S. aureus revealed that CNF_3.8 showed pronounced antibacterial effect and performed as good as the antiseptic Prontosan wound gel.

  • 24.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kirsebom, H.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Designing nanocellulose qualities for wound dressings2013Conference paper (Refereed)
  • 25.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Kuznetsova, Nina V.
    Kazan National Research Technological University, Russia.
    Garaeva, Milyausha
    Kazan National Research Technological University, Russia.
    Leirset, Ingebjörg
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Galiullina, Guzaliya
    Kazan National Research Technological University, Russia.
    Kostochko, Anatoliy V.
    Kazan National Research Technological University, Russia.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Bleached and unbleached MFC nanobarriers:: Properties and hydrophobisation with hexamethyldisilazane2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 12, article id 1280Article in journal (Refereed)
    Abstract [en]

    This study explores the production and surface modification of microfibrillated cellulose (MFC), based on unbleached and bleached Pinus radiata pulp fibres. Unbleached Pinus radiata pulp fibres tend to fibrillate easier by homogenisation without pre-treatment, compared to the corresponding bleached MFC. The resulting unbleached MFC films have higher barrier against oxygen, lower water wettability and higher tensile strength than the corresponding bleached MFC qualities. In addition, it is demonstrated that carboxymethylation can also be applied for production of highly fibrillated unbleached MFC. The nanofibril size distribution of the carboxymethylated MFC is narrow with diameters less than 20 nm, as quantified on high-resolution field-emission scanning electron microscopy images. The carboxymetylation had a larger fibrillation effect on the bleached pulp fibres than on the unbleached one. Importantly, the suitability of hexamethyldisilazane (HMDS) as a new alternative for rendering MFC films hydrophobic was demonstrated. TheHMDS-modifiedfilmsmade of carboxymethylated MFC had oxygen permeability levels better than 0.06 mL mm m-2 day-1 atm-1,which is a good property for some packaging applications.

  • 26.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Miettinen, A.
    Hendriks, C. L. L
    Gamstedt, K.
    Kataka, M.
    Structural characterisation of kraft pulp fibres and their nanofibrillated materials for biodegradable composite applications2011In: Nanocomposites and Polymers with Analytical Methods, InTech , 2011Chapter in book (Refereed)
  • 27.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University UK.
    Thomas, D.W
    Cardiff University, UK.
    Wood nanocellulose: Characterization and potential application as barrier against wound bacteria2014Conference paper (Refereed)
    Abstract [en]

    Wood nanocellulose is a novel biomaterial for wound dressing applications. Wood nanocellulose was produced from never-dried P. radiata pulp fibres. The applied pre-treatment was 2,2,6,6-tetramethylpiperidinyl-1-oxyl  (TEMPO) mediated oxidation. To characterise bacterial growth, P. aeruginosa PAO1 biofilms were grown in Mueller Hinton broth on air-dried films. Various microscopy techniques, including atomic force microscopy (AFM), confocal laser scanning microscopy (CLSM) and field-emission scanning electron microscopy (FESEM), were applied to characterise the nanocellulose material and the bacterial-nanocellulose interactions.   Multiscale assessments, including FESEM and AFM, revealed the effective fibrillation of the fibre wall structure, yielding nanofibrils with diameters less than 20 nm and lengths in the micrometre-scale. Importantly, we have demonstrated that the growth of PAO1 was inhibited in the presence of the nanocellulose suspensions when compared to the control. Additionally, SEM imaging revealed distinct clusters of PAO1 cells growing on the surfaces of nanocellulose films. This work highlights the potential usefulness of novel nanocellulose materials in wound dressings with optimized characteristics.

  • 28.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Powell, L.C
    Cardiff University School of Dentistry, UK; Swansea University, UK.
    Nordli, H.R
    NTNU Norwegian University of Science and Technology, Norway.
    Khan, S
    Cardiff University, UK.
    Hill, K.E
    Cardiff University, UK.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Thomas, D.W
    Cardiff University, UK.
    Nanocellulose from wood as a biomaterial for biomedical applications2014Conference paper (Refereed)
    Abstract [en]

    During the last decades major efforts have been made to produce nanocellulose from wood, where the cellulose fibres are disintegrated into individualized nanofibrils with diameters < 20 nm and lengths in the micrometre scale. Production procedures include various pre-treatments, which yield nanocelluloses with varying chemical and structural properties. One important area of research is nanocellulose as a biomaterial with potential applications within the health sector. As an example, the superior mechanical properties, good moisture retention capability and the ability to form elastic macro-porous structures are advantageous properties for utilizing nanocellulose substrates for wound dressings. However, the utilization of nanocellulose as a substrate for wound dressings requires a thorough assessment of the biocompatibility of the material.  In this respect, it has been demonstrated in-vitro that nanocellulose does not exert acute toxic phenomena on fibroblast cells. However, in addition to in-vitro cytotoxicity testing, in-vivo testing of nanocellulose and the ability of nanocellulose to resist bacterial colonization need a closer attention. This presentation will give an overview of the current research on nanocellulose as a biomaterial for wound dressing applications, considering the morphology of nanocellulose structures, mechanical properties, moisture absorption, cytotoxicity tests and nanocellulose-bacteria interactions.

  • 29.
    Chinga-Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Rosendahl, Jennifer
    RISE Research Institutes of Sweden, Materials and Production, Product Realisation Methodology.
    Catalán, Julia
    Finnish Institute of Occupational Health, Finland; University of Zaragoza, Spain.
    Nanocelluloses – Nanotoxicology, Safety Aspects and 3D Bioprinting2022In: Advances in Experimental Medicine and Biology, ISSN 0065-2598, E-ISSN 2214-8019, Vol. 1357, p. 155-177Article in journal (Refereed)
    Abstract [en]

    Nanocelluloses have good rheological properties that facilitate the extrusion of nanocellulose gels in micro-extrusion systems. It is considered a highly relevant characteristic that makes it possible to use nanocellulose as an ink component for 3D bioprinting purposes. The nanocelluloses assessed in this book chapter include wood nanocellulose (WNC), bacterial nanocellulose (BNC), and tunicate nanocellulose (TNC), which are often assumed to be non-toxic. Depending on various chemical and mechanical processes, both cellulose nanofibrils (CNF) and cellulose nanocrystals (CNC) can be obtained from the three mentioned nanocelluloses (WNC, BNC, and TNC). Pre/post-treatment processes (chemical and mechanical) cause modifications regarding surface chemistry and nano-morphology. Hence, it is essential to understand whether physicochemical properties may affect the toxicological profile of nanocelluloses. In this book chapter, we provide an overview of nanotoxicology and safety aspects associated with nanocelluloses. Relevant regulatory requirements are considered. We also discuss hazard assessment strategies based on tiered approaches for safety testing, which can be applied in the early stages of the innovation process. Ensuring the safe development of nanocellulose-based 3D bioprinting products will enable full market use of these sustainable resources throughout their life cycle.

  • 30.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Solheim, Olav
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Lenes, Marianne
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Larsen, Åge G.
    SINTEF, Norway.
    A method for estimating the fibre length in fibre-PLA composites2013In: Journal of Microscopy, ISSN 0022-2720, E-ISSN 1365-2818, Vol. 250, no 1, p. 15-20Article in journal (Refereed)
    Abstract [en]

    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.

  • 31.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Cellulose nanofibrils: production, characterization and applications2011In: Fine Structure of Papermaking Fibres, Swedish University of Agricultural Sciences , 2011, , p. 13Chapter in book (Refereed)
  • 32.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    On the porosity and oxygen barrier properties of cellulose nanofibril-based films2011Conference paper (Refereed)
  • 33.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    On the structure and oxygen transmission rate of biodegradable cellulose nanobarriers2012In: Nanoscale Research Letters, ISSN 1931-7573, E-ISSN 1556-276X, Vol. 7Article in journal (Refereed)
  • 34.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Pretreatment-dependent surface chemistry of wood nanocellulose for pH-sensitive hydrogels2014In: Journal of biomaterials applications, ISSN 0885-3282, E-ISSN 1530-8022, Vol. 3, no 29, p. 423-432Article in journal (Refereed)
    Abstract [en]

    Nanocellulose from wood is a promising material with potential in various technological areas. Within biomedical applications, nanocellulose has been proposed as a suitable nano-material for wound dressings. This is based on the capability of the material to self-assemble into 3D micro-porous structures, which among others have an excellent capacity of maintaining a moist environment. In addition, the surface chemistry of nanocellulose is suitable for various applications. First, OH-groups are abundant in nanocellulose materials, making the material strongly hydrophilic. Second, the surface chemistry can be modified, introducing aldehyde and carboxyl groups, which have major potential for surface functionalization. In this study, we demonstrate the production of nanocellulose with tailor-made surface chemistry, by pre-treating the raw cellulose fibres with carboxymethylation and periodate oxidation. The pre-treatments yielded a highly nanofibrillated material, with significant amounts of aldehyde and carboxyl groups. Importantly, the poly-anionic surface of the oxidized nanocellulose opens up for novel applications, i.e. micro-porous materials with pH-responsive characteristics. This is due to the swelling capacity of the 3D micro-porous structures, which have ionisable functional groups. In this study, we demonstrated that nanocellulose gels have a significantly higher swelling degree in neutral and alkaline conditions, compared to an acid environment (pH 3). Such a capability can potentially be applied in chronic wounds for controlled and intelligent release of antibacterial components into biofilms.

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  • 35.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Tobjörk, Daniel
    Åbo Akademi University, Finland.
    Österbacka, Ronald
    Åbo Akademi University, Finland.
    Inkjet-printed silver nanoparticles on nano-engineered cellulose films for electrically conducting structures and organic transistors:: concept and challenges2012In: Journal of nanoparticle research, ISSN 1388-0764, E-ISSN 1572-896X, Vol. 14, no 11, article id 1213Article in journal (Refereed)
    Abstract [en]

    This study explores the suitability of microfibrillated cellulose (MFC) films as a substrate for printing electrically conductive structures and multilayer electronic structures such as organic field effect transistors. Various MFC qualities were tested, including mechanically produced MFC, 2,2,6,6-tetramethylpiperidinyl- 1-oxyl pre-treated MFC and carboxymethylated- MFC. The films differed significantly with respect to the surface structure. In addition, the carboxymethylated-MFC films were surface modified with hexamethyldisilazane (HMDS) to reduce the water-wettability of the films, and thus, improve the print resolution of the inkjet-printed silver (Ag) nanoparticles. The Ag-particles (diameter>50 nm) were printed on the HMDS-modified films, which were mainly composed of nanofibrils with diameters >20 nm. The effect of surface roughness and surface chemical characteristics on the ink spreading and print resolution of the Ag-structures was explored. It was demonstrated that organic transistors operating at low voltages can be fabricated on nano-engineered MFC films.

  • 36.
    Chinga-Carrasco, Gary
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Yu, Y.
    Diserud, O.
    Quantitative Electron Microscopy of Cellulose Nanofibril Structures from Eucalyptus and Pinus Radiata Kraft Pulp Fibres2011In: Microscopy and Microanalysis, ISSN 1431-9276, E-ISSN 1435-8115, Vol. 17Article in journal (Refereed)
  • 37.
    Chinga-Carrasco, Gary
    et al.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Zarna, Chiara
    NTNU, Norway.
    Rodríguez-Fabià, Sandra
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Leirset, Ingebjörg
    RISE Research Institutes of Sweden.
    Tanase-Opedal, Mihaela
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Molteberg, Dag
    Norske Skog Saugbrugs, Norway.
    Echtermeyer, Andreas
    NTNU, Norway.
    Hindersland, Leif
    Alloc AS, Norway.
    Side streams from flooring laminate production – Characterisation and recycling in biocomposite formulations for injection moulding2022In: Composites. Part A, Applied science and manufacturing, ISSN 1359-835X, E-ISSN 1878-5840, Vol. 153, article id 106723Article in journal (Refereed)
    Abstract [en]

    Side streams were collected from three locations in a flooring factory and their suitability in biocomposite formulations was assessed. The side stream (S3) that contained mainly residues from high-density fibreboards (HDF) was selected for further material testing. The effect of different fractions of S3, thermomechanical pulp (TMP) fibres and polylactic acid (PLA) were assessed in terms of their mechanical, melt flow and thermal properties. A biocomposite made from PLA, 20 wt% TMP fibres and 10 wt% S3 revealed a significant increase in modulus (5800 MPa), compared to the neat PLA (3598 MPa), and a similar melt-flow index (MFI = 4.5). The tensile strength was however somewhat reduced from 66 to 58 MPa. Importantly, numerical modelling and simulations were applied to demonstrate that building a model chair out of biocomposite can potentially reduce the material volume by 12% while maintaining similar load bearing capacity, compared to neat PLA. © 2021 The Author(s)

  • 38.
    Chiulan, I.
    et al.
    ICECHIM, Romania.
    Panaitescu, D. M.
    ICECHIM, Romania.
    Radu, E. -R
    ICECHIM, Romania.
    Frone, A. N.
    ICECHIM, Romania.
    Gabor, R. A.
    ICECHIM, Romania.
    Nicolae, C. A.
    ICECHIM, Romania.
    Jinescu, G.
    Carol Davila University of Medicine and Pharmacy, Romania.
    Tofan, V.
    Cantacuzino National Institute of Research and Development for Microbiology and Immunology, Romania.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Comprehensive characterization of silica-modified silicon rubbers2020In: Journal of The Mechanical Behavior of Biomedical Materials, ISSN 1751-6161, E-ISSN 1878-0180, Vol. 101, article id 103427Article in journal (Refereed)
    Abstract [en]

    In this study a commercially liquid silicone rubber was filled with fumed silica particles in different concentrations and evaluated for medical applications. The thermal, morphological and mechanical properties of silicone/silica composite samples were studied before and after aging, flexural tests and immersion in saline environment. Understanding the effect of silica content, aging conditions and thickness (from 0.6 to 2 mm) of the samples on the behavior of these materials in different environments is crucial for applications as implantable devices. Before inducing any mechanical stress, tensile strength was found to increase for samples containing 3 or 5 wt% of fumed silica, depending on the thickness. A similar trend was observed after 106 flexes for tensile strength, storage modulus and hardness at room temperature, which increased with the concentration of fumed silica. Moreover, tensile strength decreased with increasing the thickness of the samples from 0.6 to 2 mm. The thermal degradation was found to start at higher temperature in the case of the composites as compared with neat silicone, however, the glass transition and melting temperatures were only slightly modified by the presence of the silica particles, regardless the mechanical aging. The MTT assay using L929 fibroblasts mouse cells showed a good short-time cytocompatibility for both silicone elastomer and the composite with 3 wt% fumed silica. Similarly, the measurement of the cytokine secretion revealed no inflammatory response.

  • 39.
    Chiulan, Ioana
    et al.
    The National Institute for Research and Development in Chemistry and Petrochemistry, Romania; Advanced Polymer Materials Group, University Politehnica of Bucharest, Romania.
    Heggset, Ellinor B
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Voicu, Stefan
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Photopolymerization of Bio-Based Polymers in a Biomedical Engineering Perspective2021In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 22, no 5, p. 1795-1814Article in journal (Refereed)
    Abstract [en]

    Photopolymerization is an effective method to covalently cross-link polymer chains that can be shaped into several biomedical products and devices. Additionally, polymerization reaction may induce a fluid-solid phase transformation under physiological conditions and is ideal for in vivo cross-linking of injectable polymers. The photoinitiator is a key ingredient able to absorb the energy at a specific light wavelength and create radicals that convert the liquid monomer solution into polymers. The combination of photopolymerizable polymers, containing appropriate photoinitiators, and effective curing based on dedicated light sources offers the possibility to implement photopolymerization technology in 3D bioprinting systems. Hence, cell-laden structures with high cell viability and proliferation, high accuracy in production, and good control of scaffold geometry can be biofabricated. In this review, we provide an overview of photopolymerization technology, focusing our efforts on natural polymers, the chemistry involved, and their combination with appropriate photoinitiators to be used within 3D bioprinting and manufacturing of biomedical devices. The reviewed articles showed the impact of different factors that influence the success of the photopolymerization process and the final properties of the cross-linked materials.

  • 40.
    Djafari Petroudy, Seyed Rahman
    et al.
    Shahid Beheshti University, Iran.
    Ghasemian, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Sari University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute. NTNU Norwegian University of Science and Technology, Norway.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    The effect of xylan on the fibrillation efficiency of DED bleached soda bagasse pulp and on nanopaper characteristics2015In: Cellulose, ISSN 0969-0239, E-ISSN 1572-882X, Vol. 22, no 1, p. 385-395Article in journal (Refereed)
    Abstract [en]

    Xylan is the second most abundant polysaccharide and the most abundant hemicellulose component of soda bagasse pulp. In this study, bleached soda bagasse pulp (SB) and bleached bagasse dissolving pulp (DB) with varying amounts of xylan were fibrillated with a homogenization process. The produced fibrillated materials were used for making nanopaper structures. The surface, physical, mechanical and optical properties of the nanopaper were measured, and the effect of xylan was assessed. Laser profilometry (LP) and field emission scanning electron microscopy were applied to study the degree of the fibrillation. The pulp having the highest xylan content, SB, showed the highest yield of cellulose nanofibrils. Nanopaper produced from SB had a more consolidated structure than that produced from DB. Additionally, SB nanopaper yielded higher tensile strength, lower LP roughness, a higher barrier against oxygen and lower opacity. These results indicate a higher degree of fibrillation of the SB pulp compared to the DB pulp. Hence, the positive effect of xylan for facilitating the fibrillation of the starting pulp fibers was demonstrated.

  • 41.
    Djafari Petroudy, Seyed Rahman
    et al.
    NTNU Norwegian University of Science and Technology, Norway; Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, Ali
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Resalati, Hossein
    Gorgan University of Agricultural Sciences and Natural Resources, Iran.
    Effects of bagasse microfibrillated cellulose and cationic polyacrylamide on key properties of bagasse paper2014In: Carbohydrate Polymers, ISSN 0144-8617, E-ISSN 1879-1344, Vol. 99, p. 311-318Article in journal (Refereed)
    Abstract [en]

    This study explores the benefits of using bagasse microfibrillated cellulose (MFC) in bagasse paper. Two different types of MFC were produced from DED bleached soda bagasse pulp. The MFC was added to soda bagasse pulp furnishes in different amounts. Cationic polyacrylamide (C-PAM) was selected as retention aid. The results show that addition of MFC increased the strength of paper as expected. Interestingly, 1% MFC in combination with 0.1% C-PAM yielded similar drainage time as the reference pulp, which did not contain MFC. In addition, the samples containing 1% MFC and 0.1% C-PAM yielded (i) a significant increment of the tensile index, (ii) a minor decrease of opacity and (iii) preserved Gurley porosity. Hence, this study proves that small fractions of MFC in combination with adequate retention aids can have positive effects with respect to paper properties, which is most interesting from an industrial point of view.

  • 42. Djafari Petroudy, S.R.
    et al.
    Syverud, Kristin
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Ghasemain, A.
    Resalati, H.
    Gregersen, Ø.W.
    Oriented nanopaper (ONP) made of bagasse nanofibrils2012Conference paper (Refereed)
  • 43.
    Ehman, N. V.
    et al.
    Universidad Nacional de Misiones, Argentina.
    Lourenço, A. F.
    University of Coimbra, Portugal.
    McDonagh, B. H.
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Vallejos, M. E.
    Universidad Nacional de Misiones, Argentina.
    Felissia, F. E.
    Universidad Nacional de Misiones, Argentina.
    Ferreira, P. J. T.
    University of Coimbra, Portugal.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Area, M. C.
    Universidad Nacional de Misiones, Argentina.
    Influence of initial chemical composition and characteristics of pulps on the production and properties of lignocellulosic nanofibers2020In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 143, p. 453-461Article in journal (Refereed)
    Abstract [en]

    This work aimed to study the influence of the initial chemical composition (glucans, lignin, xylan, and mannans), intrinsic viscosity, and carboxylate groups of pulps on the production process and final properties of lignocellulosic nanofibers (LCNF). Pulps of pine sawdust, eucalyptus sawdust, and sugarcane bagasse subjected to conventional pulping and highly oxidized processes were the starting materials. The LCNF were obtained by TEMPO mediated oxidation and mechanical fibrillation with a colloidal grinder. The nanofibrillation degree, chemical charge content, rheology, laser profilometry, cristallinity and atomic force microscopy were used to characterize the LCNF. The carboxylate groups, hemicelluloses and lignin of the initial pulps were important factors that affected the production process of LCNF. The results revealed that intrinsic viscosity and carboxylate groups of the initial pulps affected LCNF production process, whereas lignin and hemicelluloses influenced the viscosity of LCNF aqueous suspensions, the roughness of LCNF films, and the carboxylate groups content of LCNF

  • 44.
    Ehman, Nanci Vanesa
    et al.
    IMAM Instituto de Materiales de Misiones, Argentina.
    Ita-Nagy, Diana
    Pontificia Universidad Católica del Perú, Peru.
    Felissia, Fernando Esteban
    IMAM Instituto de Materiales de Misiones, Argentina.
    Vallejos, María Evangelina
    IMAM Instituto de Materiales de Misiones, Argentina.
    Quispe, Isabel
    Pontificia Universidad Católica del Perú, Peru.
    Area, María Cristina
    IMAM Instituto de Materiales de Misiones, Argentina.
    Chinga-Carrasco, Gary
    RISE Research Institutes of Sweden, Bioeconomy and Health, Material and Surface Design.
    Biocomposites of Bio-Polyethylene Reinforced with a Hydrothermal-Alkaline Sugarcane Bagasse Pulp and Coupled with a Bio-Based Compatibilizer.2020In: Molecules, ISSN 1431-5157, E-ISSN 1420-3049, Vol. 25, no 9, article id E2158Article in journal (Refereed)
    Abstract [en]

    Bio-polyethylene (BioPE, derived from sugarcane), sugarcane bagasse pulp, and two compatibilizers (fossil and bio-based), were used to manufacture biocomposite filaments for 3D printing. Biocomposite filaments were manufactured and characterized in detail, including measurement of water absorption, mechanical properties, thermal stability and decomposition temperature (thermo-gravimetric analysis (TGA)). Differential scanning calorimetry (DSC) was performed to measure the glass transition temperature (Tg). Scanning electron microscopy (SEM) was applied to assess the fracture area of the filaments after mechanical testing. Increases of up to 10% in water absorption were measured for the samples with 40 wt% fibers and the fossil compatibilizer. The mechanical properties were improved by increasing the fraction of bagasse fibers from 0% to 20% and 40%. The suitability of the biocomposite filaments was tested for 3D printing, and some shapes were printed as demonstrators. Importantly, in a cradle-to-gate life cycle analysis of the biocomposites, we demonstrated that replacing fossil compatibilizer with a bio-based compatibilizer contributes to a reduction in CO2-eq emissions, and an increase in CO2 capture, achieving a CO2-eq storage of 2.12 kg CO2 eq/kg for the biocomposite containing 40% bagasse fibers and 6% bio-based compatibilizer.

  • 45.
    Espinosa, Eduardo
    et al.
    University of Córdoba, Spain.
    Bascón-Villegas, Isabel
    University of Córdoba, Spain.
    Rosal, Antonio
    University Pablo de Olavide, Spain.
    Pérez-Rodríguez, Fernando
    University of Córdoba, Spain.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Rodríguez, Alejandro
    University of Córdoba, Spain.
    PVA/(ligno)nanocellulose biocomposite films. Effect of residual lignin content on structural, mechanical, barrier and antioxidant properties2019In: International Journal of Biological Macromolecules, ISSN 0141-8130, E-ISSN 1879-0003, Vol. 141, p. 197-206Article in journal (Refereed)
    Abstract [en]

    Nanocelluloses with and without residual lignin were isolated from wheat straw. In addition, the effect of TEMPO-mediated oxidation on the production of lignin-containing nanocellulose was studied. The different nanocelluloses were used as reinforcing agent in Poly(vinyl alcohol) films. The morphology, crystallinity, surface microstructure, barrier properties, light transmittance, mechanical and antioxidant properties were evaluated. The translucency of films was reduced by the addition of nanocellulose, however, the ability to block UV-light increased from 10% for PVA to >50% using lignin-containing nanocellulose, and 30% for lignin-free samples. The mechanical properties increased considerably, however, for loads higher than 5% a negative trend was observed presumptively due to a clustering of nanocellulose components in PVA matrix. The barrier properties of the films were improved with the use of nanocellulose, especially at small amounts (1–3%). The antioxidant capacity of films was increased up to 10% using lignin-containing nanocellulose compared to 4.7% using PVA. © 2019 Elsevier B.V.

  • 46.
    Espinosa, Eduardo
    et al.
    Universidad de Cordoba, Spain.
    Filgueira, Daniel
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, PFI.
    Rodríguez, Alejandro
    Universidad de Cordoba, Spain.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, PFI.
    Nanocellulose-Based Inks-Effect of Alginate Content on the Water Absorption of 3D Printed Constructs.2019In: Bioengineering (Basel, Switzerland), ISSN 2306-5354, Vol. 6, no 3, article id E65Article in journal (Refereed)
    Abstract [en]

    2,2,6,6-tetramethylpyperidine-1-oxyl (TEMPO) oxidized cellulose nanofibrils (CNF) were used as ink for three-dimensional (3D) printing of porous structures with potential as wound dressings. Alginate (10, 20, 30 and 40 wt%) was incorporated into the formulation to facilitate the ionic cross-linking with calcium chloride (CaCl2). The effect of two different concentrations of CaCl2 (50 and 100 mM) was studied. The 3D printed hydrogels were freeze-dried to produce aerogels which were tested for water absorption. Scanning Electronic Microscopy (SEM) pictures demonstrated that the higher the concentration of the cross-linker the higher the definition of the printed tracks. CNF-based aerogels showed a remarkable water absorption capability. Although the incorporation of alginate and the cross-linking with CaCl2 led to shrinkage of the 3D printed constructs, the approach yielded suitable porous structures for water and moisture absorption. It is concluded that the 3D printed biocomposite structures developed in this study have characteristics that are promising for wound dressings devices.

  • 47.
    Filgueira, Daniel
    et al.
    University of Vigo, Spain.
    Holmen, Solveig
    NTNU, Norway.
    Melbø, Johnny K.
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, PFI.
    Moldes, Diego
    University of Vigo, Spain.
    Echtermeyer, Andreas T.
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden (2017-2019), Bioeconomy, PFI.
    3D printable filaments made of biobased polyethylene biocomposites2018In: Polymers, E-ISSN 2073-4360, Vol. 10, no 3, article id 314Article in journal (Refereed)
    Abstract [en]

    Two different series of biobased polyethylene (BioPE) were used for the manufacturing of biocomposites, complemented with thermomechanical pulp (TMP) fibers. The intrinsic hydrophilic character of the TMP fibers was previously modified by grafting hydrophobic compounds (octyl gallate and lauryl gallate) by means of an enzymatic-assisted treatment. BioPE with low melt flow index (MFI) yielded filaments with low void fraction and relatively low thickness variation. The water absorption of the biocomposites was remarkably improved when the enzymatically-hydrophobized TMP fibers were used. Importantly, the 3D printing of BioPE was improved by adding 10% and 20% TMP fibers to the composition. Thus, 3D printable biocomposites with low water uptake can be manufactured by using fully biobased materials and environmentally-friendly processes.

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  • 48.
    Filgueira, Daniel
    et al.
    University of Vigo, Spain.
    Holmen, Solveig
    NTNU, Norway.
    Melbø, Johnny K.
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Moldes, Diego
    University of Vigo, Spain.
    Echtermeyer, Andreas T.
    NTNU, Norway.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Enzymatic-Assisted Modification of Thermomechanical Pulp Fibers to Improve the Interfacial Adhesion with Poly(lactic acid) for 3D Printing2017In: ACS Sustainable Chemistry and Engineering, E-ISSN 2168-0485, Vol. 5, no 10, p. 9338-9346Article in journal (Refereed)
    Abstract [en]

    The present study is about the enzymatic modification of thermomechanical pulp (TMP) fibers for reduction of water uptake and their use in bio-based filaments for 3D printing. Additionally, TMP was used as a fiber reinforcing material and poly(lactic acid) (PLA) as the polymer matrix. The hydrophilic TMP fibers were treated via laccase-assisted grafting of octyl gallate (OG) or lauryl gallate (LG) onto the fiber surface. The modified TMP fibers showed remarkable hydrophobic properties, as demonstrated by water contact angle measurements. Filaments reinforced with OG-treated fibers exhibited the lowest water absorption and the best interfacial adhesion with the PLA matrix. Such higher chemical compatibility between the OG-treated fibers and the PLA enabled better stress transfer from the matrix to the fibers during mechanical testing, which led to the manufacture of strong filaments for 3D printing. All of the manufactured filaments were 3D-printable, although the filaments containing OG-treated fibers yielded the best results. Hence, laccase-mediated grafting of OG onto TMP fibers is a sustainable and environmentally friendly pathway for the manufacture of fully bio-based filaments for 3D printing.

  • 49.
    Gamelas, José A. F.
    et al.
    University of Coimbra, Portugal.
    Pedrosa, Jorge
    University of Coimbra, Portugal.
    Lourenco, Ana F.
    University of Coimbra, Portugal.
    Mutjo, Peré
    University of Girona, Spain.
    Gonzalez, Israel
    University of Girona, Spain.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Singh, Gurvinder
    NTNU Norwegian University of Science and Technology, Norway.
    Ferreira, Paulo J. T.
    University of Coimbra, Portugal.
    On the morphology of cellulose nanofibrils obtained by TEMPO-mediated oxidation and mechanical treatment2015In: Micron, ISSN 0968-4328, E-ISSN 1878-4291, Vol. 72, p. 28-33Article in journal (Refereed)
    Abstract [en]

    The morphological properties of cellulose nanofibrils obtained from eucalyptus pulp fibres were assessed. Two samples were produced with the same chemical treatment (NaClO/NaBr/TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical) oxidation), but distinct mechanical treatment intensities during homogenization. It was shown that the nanofibrils production yield increases with the mechanical energy. The effect of mechanical treatment on the yield was confirmed by laser profilometry of air-dried nanocellulose films. However, no significant differences were detected regarding the nanofibrils width as measured by atomic force microscopy (AFM) of air-dried films. On the other hand, differences in size were found either by laser diffraction spectroscopy or by dynamic light scattering (DLS) of the cellulose nanofibrils suspensions as a consequence of the differences in the length distribution of both samples. The nanofibrils length of the more nanofibrillated sample was calculated based on the width measured by AFM and the hydrodynamic diameter obtained by DLS. A length value of ca. 600. nm was estimated. The DLS hydrodynamic diameter, as an equivalent spherical diameter, was used to estimate the nanofibrils length assuming a cylinder with the same volume and with the diameter (width) assessed by AFM. A simple method is thus proposed to evaluate the cellulose nanofibrils length combining microscopy and light scattering methods.

  • 50.
    Ghose, Agneta
    et al.
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Chinga-Carrasco, Gary
    RISE, Innventia, PFI – Paper and Fiber Research Institute.
    Environmental Aspects of Norwegian production of pulp fibres and printing paper2013In: Journal of Cleaner Production, ISSN 0959-6526, E-ISSN 1879-1786, Vol. 57, p. 293-301Article in journal (Refereed)
    Abstract [en]

    The purpose of this study was to assess the environmental impacts of the Norwegian pulp and paper industry, considering the production of pulp fibres and printing paper. The pulp fibres included in this study are thermo-mechanical pulp and kraft pulp fibres, which differ with respect to the energy consumption and chemicals used during production. The assessed paper grades were super-calendered paper and newsprint. The study was a cradle to gate approach, and corresponds to an attributional life cycle assessment (LCA). The LCA was based on data collected from main pulp and paper producers in Norway. Importantly, aspects related to the increasing use of mineral fillers in the production of newsprints were assessed. The results showed that a reduction of more than 18% climate change impact (kg CO2 eq.) was achieved by increasing the fraction of fillers, in the newsprint furnish. Furthermore, the total climate change impact reduction depended on the applied energy mix. Assuming that the production of printing paper was based only on Norwegian energy mix, yielded a reduction of the climate change impact by more than 44% in 2011, compared to the production based on Scandinavian and European energy mix. Additionally, the input and output transport contributed to more than 20% impact in several cases. We thus concluded that the estimated environmental impacts were affected by; i) the furnish composition of a given paper quality, ii) the input and output transport and iii) the use of different primary grid energy sources.

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