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  • 1. Albertsson, A.-C.
    et al.
    Voepel, J.
    Edlund, U.
    Dahlman, Olof
    RISE, Innventia.
    Söderqvist-Lindblad, M.
    Design of renewable hydrogel release systems from fiberboard mill wastewater2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 5, p. 1406-1411Article in journal (Refereed)
    Abstract [en]

    A new route for the design of renewable hydrogels is presented. The soluble waste from masonite production was isolated, fractionized, and upgraded. The resulting hemicellulose rich fraction was alkenyl-functionalized and used in the preparation of covalently cross-linked hydrogels capable of sustained release of incorporated agents. Said hydrogels showed a Fickian diffusion-based release of incorporated bovine serum albumin. Also, a method for the coating of seeds with hydrogel was developed. The sustained release of incorporated growth retardant agents from the hydrogel coating on rape seeds was shown to enable the temporary inhibition of germination.

  • 2.
    Andersson Trojer, Markus
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF. Max Planck Institute of Colloids and Interfaces, Germany.
    Andersson, Mats
    Chalmers University of Technology, Sweden; Flinders University, Australia.
    Bergenholtz, Johan
    University of Gothenburg, Sweden.
    Gatenholm, Paul
    Chalmers University of Technology, Sweden.
    Quantitative Grafting for Structure-Function Establishment: Thermoresponsive Poly(alkylene oxide) Graft Copolymers Based on Hyaluronic Acid and Carboxymethylcellulose2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 3, p. 1271-1280Article in journal (Refereed)
    Abstract [en]

    A series of thermoresponsive graft copolymers, gelling at physiological conditions in aqueous solution and cell growth media, have been synthesized using quantitative coupling between a small set of amino-functionalized poly(alkylene oxide) copolymers (PAO) and the carboxylate of the biologically important polysaccharides (PSa) carboxymethylcellulose and the less reactive hyaluronate. Quantitative grafting enables the establishment of structure-function relationship which is imperative for controlling the properties of in situ gelling hydrogels. The EDC/NHS-mediated reaction was monitored using SEC-MALLS, which revealed that all PAOs were grafted onto the PSa backbone. Aqueous solutions of the graft copolymers were Newtonian fluids at room temperatures and formed reversible physical gels at elevated temperatures which were noncytotoxic toward chondrocytes. The established structure-function relationship was most clearly demonstrated by inspecting the thermogelling strength and the onset of thermogelling in a phase diagram. The onset of the thermogelling function could be controlled by the global PAO concentration, independent of graft ratio.

  • 3. Aulin, C.
    et al.
    Johansson, E.
    Wågberg, L.
    Lindström, Tom
    RISE, Innventia.
    Self-organized films from cellulose i nanofibrils using the layer-by-layer technique2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 4, p. 872-882Article in journal (Refereed)
    Abstract [en]

    The possibility of forming self-organized films using only charge-stabilized dispersions of cellulose I nanofibrils with opposite charges is presented, that is, the multilayers were composed solely of anionically and cationically modified microfibrillated cellulose (MFC) with a low degree of substitution. The build-up behavior and the properties of the layer-by-layer (LbL)-constructed films were studied using a quartz crystal microbalance with dissipation (QCM-D) and stagnation point adsorption reflectometry (SPAR). The adsorption behavior of cationic/anionic MFC was compared with that of polyethyleneimine (PEI)/anionic MFC. The water contents of five bilayers of cationic/anionic MFC and PEI/anionic MFC were approximately 70 and 50%, respectively. The MFC surface coverage was studied by atomic force microscopy (AFM) measurements, which clearly showed a more dense fibrillar structure in the five bilayer PEI/anionic MFC than in the five bilayer cationic/anionic MFC. The forces between the cellulose-based multilayers were examined using the AFM colloidal probe technique. The forces on approach were characterized by a combination of electrostatic and steric repulsion. The wet adhesive forces were very long-range and were characterized by multiple adhesive events. Surfaces covered by PEI/anionic MFC multilayers required more energy to be separated than surfaces covered by cationic/anionic MFC multilayers.

  • 4.
    Bjurhager, I.
    et al.
    RISE, Innventia.
    Halonen, H.
    RISE, Innventia.
    Lindfors, E.-L.
    RISE, Innventia.
    Iversen, T.
    RISE, Innventia.
    Almkvist, G.
    Gamstedt, E.K.
    Berglund, L.A.
    State of degradation in archeological oak from the 17th century vasa ship: Substantial strength loss correlates with reduction in (holo)cellulose molecular weight2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 8, p. 2521-2527Article in journal (Refereed)
  • 5. Bjurhager, I.
    et al.
    Olsson, Anne-Mari
    RISE, Innventia.
    Zhang, B.
    Gerber, L.
    Kumar, M.
    Berglund, Lars A.
    Burgert, I.
    Sundberg, B.
    Salmen, Lennart
    RISE, Innventia.
    Ultrastructure and mechanical properties of populus wood with reduced lignin content caused by transgenic down-regulation of cinnamate 4-hydroxylase2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 9, p. 2359-2365Article in journal (Refereed)
    Abstract [en]

    Several key enzymes in lignin biosynthesis of Populus have been down-regulated by transgenic approaches to investigate their role in wood lignification and to explore their potential for lignin modification. Cinnamate 4-hydroxylase is an enzyme in the early phenylpropanoid pathway that has not yet been functionally analyzed in Populus. This study shows that down-regulation of cinnamate 4-hydroxylase reduced Klason lignin content by 30% with no significant change in syringyl to guaiacyl ratio. The lignin reduction resulted in ultrastructural differences of the wood and a 10% decrease in wood density. Mechanical properties investigated by tensile tests and dynamic mechanical analysis showed a decrease in stiffness, which could be explained by the lower density. The study demonstrates that a large modification in lignin content only has minor influences on tensile properties of wood in its axial direction and highlights the usefulness of wood modified beyond its natural variation by transgene technology in exploring the impact of wood biopolymer composition and ultrastructure on its material properties.

  • 6. Cardenas, M
    et al.
    Elofsson, Ulla
    YKI – Ytkemiska institutet.
    Lindh, L
    Salivary mucin MUC5B could be an important component of in vitro pellicles of human saliva: An in situ ellipsometry and atomic force microscopy study2007In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 8, no 4, p. 1149-1156Article in journal (Refereed)
    Abstract [en]

    This paper describes a combined investigation of the salivary and MUC5B films structure and topography in conditions similar to those found in the oral cavity in terms of ionic strength, pH, and protein concentration. AFM and ellipsometry were successfully used to give a detailed picture of the film structure and topography both on hydrophilic and on hydrophobic substrata. Regardless of the substrata, the salivary film can be described as having a two sublayer structure in which an inner dense layer is decorated by large aggregates. However, the shape and height of these larger aggregates largely depend on the type of substrata used. Additionally, we show that the adsorption of MUC5B is controlled by the type of substrata and the MUC5B film topography is similar to that of the larger aggregates present in the salivary films, especially on hydrophobic substrates. Therefore, we conclude that MUC5B is a major component in the salivary film when formed on hydrophobic substrates. Furthermore, we studied how resistant the salivary and MUC5B films are against elutability by buffer rinsing and addition of SDS solution. We conclude that the adsorbed proteins contain fractions with varying binding strengths to the two types of surfaces. Specifically, we have shown that the large MUC5B biomacromolecules on the hydrophobic substrates are especially resistant to both elution with buffer solution and SDS. Therefore, these large mucins can be responsible for the increased resistance of HWS films on hydrophobic substrates and can protect the intraoral surfaces against surface-active components present in oral health care products.

  • 7.
    Cervin, Nicholas Tchang
    et al.
    KTH Royal Institute of Technology, Sweden.
    Johansson, Erik
    Cellutech AB, Sweden.
    Benjamins, Jan-Willem
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Mechanisms behind the Stabilizing Action of Cellulose Nanofibrils in Wet-Stable Cellulose Foams2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 3, p. 822-831Article in journal (Refereed)
    Abstract [en]

    The principal purpose of the investigation was to clarify the mechanisms behind the stabilizing action of cellulose nanofibrils (CNFs) in wet-stable cellulose foams. Following the basic theories for particle-stabilized foams, the investigation was focused on how the surface energy of the stabilizing CNF particles, their aspect ratio and charge density, and the concentration of CNF particles at the air–water interface affect the foam stability and the mechanical properties of a particle-stabilized air–liquid interface. The foam stability was evaluated from how the foam height changed over time, and the mechanical properties of the interface were evaluated as the complex viscoelastic modulus of the interface using the pendant drop method. The most important results and conclusions are that CNFs can be used as stabilizing particles for aqueous foams already at a concentration as low as 5 g/L. The major reasons for this were the small dimensions of the CNF and their high aspect ratio, which is important for gel-formation and the complex viscoelastic modulus of the particle-filled air–water interface. The influence of the aspect ratio was also demonstrated by a much higher foam stability of foams stabilized with CNFs than of foams stabilized by cellulose nanocrystals (CNC) with the same chemical composition. The charge density of the CNFs affects the level of liberation within larger aggregates and hence also the number of contact points at the interface and the gel formation and complex viscoelastic modulus of the air–water interface. The charges also result in a disjoining pressure related to the long-range repulsive electrostatic pressure between particle-stabilized bubbles and hence contribute to foam stability.

  • 8.
    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.

  • 9.
    Dedinaite, Andra
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Polymer och fiber.
    Claesson, Per
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Comparison of a brush-with-anchor and a train-of-brushes mucin on poly(methyl methacrylate) surfaces: Adsorption, surface forces, and friction2014In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 15, no 4, p. 1515-1525Article in journal (Refereed)
  • 10.
    Edlund, Ulrica
    et al.
    KTH Royal Institute of Technology, Sweden.
    Lagerberg, Tove
    Ålander, Eva
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Admicellar Polymerization Coating of CNF Enhances Integration in Degradable Nanocomposites2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 684-692Article in journal (Refereed)
    Abstract [en]

    A water-based one-pot synthesis strategy for converting cellulose nanofibrils (CNF) into a hydrophobic and processable biopolymer grade is devised. CNF was chemically modified through admicellar polymerization, producing fibrils coated with fatty acrylate polymers. The proposed modification targets a change in the interfibrillar interactions and improved CNF compatibility with a degradable plastic composite matrix, poly(butylene adipate-co-terephthalate), PBAT in composites prepared by melt extrusion. CNF had a clear reinforcing effect on PBAT, increasing Young's modulus by at least 35% and 169% at 5 and 20% (w/w) CNF content, respectively. However, unmodified CNF showed aggregation, poor adhesion in the matrix, and severely impaired the ductility of PBAT. CNF modified by admicellar polymerization was homogeneously dispersed in the PBT matrix and showed significantly better preservation of the elongation properties compared to unmodified CNF, especially at 5% (w/w) addition level.

  • 11.
    Erlandsson, Johan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Françon, Hugo
    KTH Royal Institute of Technology, Sweden.
    Marais, Andrew
    KTH Royal Institute of Technology, Sweden.
    Granberg, Hjalmar
    RISE - Research Institutes of Sweden, Bioeconomy, Papermaking and Packaging.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Cross-Linked and Shapeable Porous 3D Substrates from Freeze-Linked Cellulose Nanofibrils.2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 2, p. 728-737Article in journal (Refereed)
    Abstract [en]

    Chemically cross-linked highly porous nanocellulose aerogels with complex shapes have been prepared using a freeze-linking procedure that avoids common post activation of cross-linking reactions and freeze-drying. The aerogel shapes ranged from simple geometrical three-dimensional bodies to swirls and solenoids. This was achieved by molding or extruding a periodate oxidized cellulose nanofibril (CNF) dispersion prior to chemical cross-linking in a regular freezer or by reshaping an already prepared aerogel by plasticizing the structure in water followed by reshaping and locking the aerogel into its new shape. The new shapes were most likely retained by new cross-links formed between CNFs brought into contact by the deformation during reshaping. This self-healing ability to form new bonds after plasticization and redrying also contributed to the mechanical resilience of the aerogels, allowing them to be cyclically deformed in the dry state, reswollen with water, and redried with good retention of mechanical integrity. Furthermore, by exploiting the shapeability and available inner structure of the aerogels, a solenoid-shaped aerogel with all surfaces coated with a thin film of conducting polypyrrole was able to produce a magnetic field inside the solenoid, demonstrating electromagnetic properties. Furthermore, by biomimicking the porous interior and stiff exterior of the beak of a toucan bird, a functionalized aerogel was created by applying a 300 μm thick stiff wax coating on its molded external surfaces. This composite material displayed a 10-times higher elastic modulus compared to that of the plain aerogel without drastically increasing the density. These examples show that it is possible to combine advanced shaping with functionalization of both the inner structure and the surface of the aerogels, radically extending the possible use of CNF aerogels.

  • 12. Fransson, S.
    et al.
    Loren, Niklas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Altskär, Annika
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Effect of confinement and kinetics on the morphology of phase separating gelatin-maltodextrin droplets2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 6, p. 1446-1453Article in journal (Refereed)
    Abstract [en]

    The effect of confinement on the structure evolution and final morphology during phase separation and gelation of gelatin and maltodextrin was investigated and compared to the structures seen in bulk phase. Emulsion droplets with diameters from 4 to 300 ?m were analyzed using confocal laser scanning microscopy and image analysis. With the confocal laser scanning microscope it was possible to follow the entire phase separating process inside the droplets in real-time. The samples were either quenched directly from 70°C down to 20°C or exposed to holding times at 40°C. Different cooling procedures were studied to examine the structure evolution both before and after gelation in the restricted geometries. The concentration of the biopolymer mixture was kept constant at 4 w/w% gelatin and 6 w/w% maltodextrin. The results revealed that the size of the confinement had a great effect on both the initiation of phase separation and the final morphology of the microstructure inside the emulsion droplets. The phase separation in small droplets was observed to occur at a temperature above the phase separating temperature for bulk. Small droplets had either a microstructure with a shell of maltodextrin and core of gelatin or a microstructure where the two biopolymers had formed two separate bicontinuous halves. The initiation of phase separation in large droplets was similar to what was seen in bulk. The microstructure in large droplets was discontinuous, resembling the morphology in bulk phase. The kinetics had an effect on the character of the maltodextrin inclusions, as the cooling procedure of a direct quench gave spherical inclusions with an even size distribution, while a holding time at 40°C resulted in asymmetrical and elongated inclusions. © 2009 American Chemical Society.

  • 13.
    Galland, Sylvain
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Prakobna, Kasinee
    KTH Royal Institute of Technology, Swedenk.
    Berglund, Lars A.
    KTH Royal Institute of Technology, Sweden.
    Holocellulose Nanofibers of High Molar Mass and Small Diameter for High-Strength Nanopaper2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 8, p. 2427-2435Article in journal (Refereed)
    Abstract [en]

    Wood cellulose nanofibers (CNFs) based on bleached pulp are different from the cellulose microfibrils in the plant cell wall in terms of larger diameter, lower cellulose molar mass, and modified cellulose topochemistry. Also, CNF isolation often requires high-energy mechanical disintegration. Here, a new type of CNFs is reported based on a mild peracetic acid delignification process for spruce and aspen fibers, followed by low-energy mechanical disintegration. Resulting CNFs are characterized with respect to geometry (AFM, TEM), molar mass (SEC), and polysaccharide composition. Cellulose nanopaper films are prepared by filtration and characterized by UV-vis spectrometry for optical transparency and uniaxial tensile tests. These CNFs are unique in terms of high molar mass and cellulose-hemicellulose core-shell structure. Furthermore, the corresponding nanopaper structures exhibit exceptionally high optical transparency and the highest mechanical properties reported for comparable CNF nanopaper structures. (Graph Presented).

  • 14.
    Ghanadpour, Maryam
    et al.
    KTH Royal Institute of Technology, Sweden.
    Carosio, Federico
    Polytechnic University of Turin, Italy.
    Larsson, Per Tomas
    RISE, Innventia. KTH Royal Institute of Technology, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Phosphorylated Cellulose Nanofibrils: A Renewable Nanomaterial for the Preparation of Intrinsically Flame-Retardant Materials2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 10, p. 3399-3410Article in journal (Refereed)
    Abstract [en]

    Cellulose from wood fibers can be modified for use in flame-retardant composites as an alternative to halogen-based compounds. For this purpose, sulfite dissolving pulp fibers have been chemically modified by phosphorylation, and the resulting material has been used to prepare cellulose nanofibrils (CNF) that have a width of approximately 3 nm. The phosphorylation was achieved using (NH4)2HPO4 in the presence of urea, and the degree of substitution by phosphorus was determined by X-ray photoelectron spectroscopy, conductometric titration, and nuclear magnetic resonance spectroscopy. The presence of phosphate groups in the structure of CNF has been found to noticeably improve the flame retardancy of this material. The nanopaper sheets prepared from phosphorylated CNF showed self-extinguishing properties after consecutive applications of a methane flame for 3 s and did not ignite under a heat flux of 35 kW/m2, as shown by flammability and cone calorimetry measurements, respectively.

  • 15.
    Gillgren, Thomas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Barker, S.A.
    Belton, P.S.
    Georget, D.M.R.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Plasticization of zein: A thermomechanical, FTIR, and dielectric study2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 5, p. 1135-1139Article in journal (Refereed)
    Abstract [en]

    Zein, the main seed storage protein of maize, has been widely studied as a possible source of material for the production of biodegradable plastic films. Plasticization of zein is critical to make functional films. While there have been a number of publications which report the behavior of systems with a wide variety of plasticizers, there have been few which attempt to examine the interactions of protein and plasticizer at the molecular level. In this paper, we report on the plasticizing effects of water, glycerol, and 2-mercaptoethanol, which were examined by a combination of spectroscopy (FTIR and dielectric) and thermomechanical methods. The results suggest that both water and glycerol are adsorbed onto the protein and form hydrogen bonds with the amide groups. The plasticizer then builds up in patches on the protein surface. 2-Mercaptoethanol only exhibited a weak plasticizing effect due probably to disulfide bond breaking. © 2009 American Chemical Society.

  • 16.
    Hagman, Joel
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Loren, Niklas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Effect of gelatin gelation kinetics on probe diffusion determined by FRAP and rheology2010In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 11, no 12, p. 3359-3366Article in journal (Refereed)
    Abstract [en]

    The time-dependent diffusion and mechanical properties of gelatin in solution, in the gel state, and during the sol/gel transition were determined using fluorescence recovery after photobleaching (FRAP) and rheology. The parameters in the experimental design were 2% w/w and 5% w/w gelatin concentration; 15, 20, and 25?C end quench temperatures; and Na 2-fluorescein, 10 kDa FITC-dextran, and 500 kDa FITC-dextran as diffusion probes. The samples were monitored in solution at 60?C, during quenching, for 75 min at end quench temperatures and after 1, 7, and 14 days of storage at the end quench temperature. The effect of temperature on the probe diffusion was normalized by determining the free diffusion of the probes in pure water for the different temperatures. The results gained by comparing FRAP and rheology showed that FRAP is able to capture structural changes in the gelatin before gelation occurs, which was interpreted as a formation of transient networks. This was clearly seen for 2% w/w gelatin and 20 and 25?C end quench temperatures. The structural changes during sol/gel transition are detected only by the larger probes, giving information about the typical length scales in the gelatin structure. The normalized diffusion rate increased after 7 and 14 days of storage. This increase was most pronounced for fluorescein but was also seen for the larger probes. © 2010 American Chemical Society.

  • 17. Henriksson, M.
    et al.
    Berglund, L. A.
    Isaksson, P.
    Lindström, Tom
    RISE, STFI-Packforsk.
    Nishino, T.
    Cellulose nanopaper structures of high toughness2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Biomacromolecules, Vol. 9, no 6, p. 1579-1585Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils offer interesting potential as a native fibrous constituent of mechanical performance exceeding the plant fibers in current use for commercial products. In the present study, wood nanofibrils are used to prepare porous cellulose nanopaper of remarkably high toughness. Nanopapers of different porosities and from nanofibrils of different molar mass are prepared. Uniaxial tensile tests are performed and structure - property relationships are discussed. The high toughness of highly porous nanopaper is related to the nanofibrillar network structure and high mechanical nanofibril performance. Also, molar mass correlates with tensile strength. This indicates that nanofibril fracture controls ultimate strength. Furthermore, the large strain-to-failure means that mechanisms, such as interfibril slippage, also contributes to inelastic deformation in addition to deformation of the nanofibrils themselves. © 2008 American Chemical Society.

  • 18.
    Hernandez-Cerdan, Pablo
    et al.
    Institute of Fundamental Sciences, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand; Riddet Insitute, New Zealand.
    Mansel, Bradley W
    Institute of Fundamental Sciences, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.
    Leis, Andrew
    The University of Melbourne, Australia.
    Lundin, Leif
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Williams, Martin A K
    Institute of Fundamental Sciences, New Zealand; The MacDiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.
    Structural Analysis of Polysaccharide Networks by Transmission Electron Microscopy: Comparison with Small-Angle X-ray Scattering2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 989-995Article in journal (Refereed)
    Abstract [en]

    Polysaccharide gels assembled from the anionic biopolymers pectin and carrageenan have been studied using transmission electron microscopy (TEM). Gels were formed in several different ways: for pectin, hydrogen bonding was used to form junction zones between strands, whereas for carrageenan systems, several different ion types were used to form ionotropic networks. Using this approach, several distinct network architectures were realized. In addition to preparing gelled samples for electron microscopy, a set of samples was taken without performing the additional treatment necessitated by the TEM measurements, and these were studied directly by small-angle X-ray scattering (SAXS). Taking careful consideration of the relative merits of different image sizes and available processing techniques, the real-space images acquired by TEM were used via radial integration of the Fourier transform to produce simulated scattering patterns. These intensity-versus-wavevector plots were compared with the results of SAXS experiments carried out on the unadulterated gels using synchrotron radiation. Although information regarding chain thicknesses and flexibilities was found to be modified by labeling and changes in the dielectric constant and mechanical properties of the surroundings in the TEM, the studies carried out here show that careful protocols can produce data sets where information acquired above ∼20 nm is broadly consistent with that obtained by SAXS studies carried out on unadulterated samples. The fact that at larger length scale the structure of these water-rich networks seems largely preserved in the TEM samples suggests that three-dimensional (3D) TEM tomography experiments carried out with careful sample preparation will be valuable tools for measuring network architecture and connectivity; information that is lost in SAXS owing to the intrinsic averaging nature of the technique.

  • 19.
    Hua, Kai
    et al.
    Uppsala University, Sweden.
    Ålander, Eva
    RISE, Innventia.
    Lindström, Tom
    RISE, Innventia.
    Mihranyan, Albert
    Uppsala University, Sweden.
    Strömme, Maria
    Uppsala University, Sweden.
    Ferraz, Natalia
    Uppsala University, Sweden.
    Surface Chemistry of Nanocellulose Fibers Directs Monocyte/Macrophage Response2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 9, p. 2787-2795Article in journal (Refereed)
    Abstract [en]

    The effect of surface functionalization of nanofibrillated cellulose (NFC) on monocyte/macrophage (MM) behavior is investigated to understand how the physicochemical properties of nanocelluloses influence the interactions of such materials with biological systems. Films of anionic (a-), cationic (c-), and unmodified (u-) NFC were synthesized and characterized in terms of surface charge. THP-1 monocytes were cultured on the surface of the films for 24 h in the presence and absence of lipopolysaccharide, and the cell response was evaluated in terms of cell adhesion, morphology, and secretion of TNF-α, IL-10, and IL-1ra. The results show that MMs cultured on carboxymethylated-NFC films (a-NFC) are activated toward a proinflammatory phenotype, whereas u-NFC promotes a mild activation of the studied cells. The presence of hydroxypropyltrimethylammonium groups on c-NFC, however, does not promote the activation of MMs, indicating that c-NFC closely behaves as an inert material in terms of MM activation. None of the materials is able to directly activate the MMs toward an anti-inflammatory response. These results may provide a foundation for the design of future NFC-based materials with the ability to control MM activation and may expand the use of NFC in biomedical applications.

  • 20.
    Jack, Alison A
    et al.
    Cardiff University School of Dentistry, UK.
    Nordli, Henriette R
    NTNU, Norway.
    Powell, Lydia C
    Cardiff University School of Dentistry, UK.
    Farnell, Damian J J
    Cardiff University School of Dentistry, UK.
    Pukstad, Brita
    NTNU, Norway; Trondheim University Hospital, Norway.
    Rye, Philip D
    AlgiPharma AS, Norway.
    Thomas, David W
    Cardiff University School of Dentistry, UK.
    Chinga-Carrasco, Gary
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Hill, Katja E
    Cardiff University School of Dentistry, UK.
    Cellulose Nanofibril Formulations Incorporating a Low-Molecular-Weight Alginate Oligosaccharide Modify Bacterial Biofilm Development.2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) from wood pulp are a renewable material possessing advantages for biomedical applications because of their customizable porosity, mechanical strength, translucency, and environmental biodegradability. Here, we investigated the growth of multispecies wound biofilms on CNF formulated as aerogels and films incorporating the low-molecular-weight alginate oligosaccharide OligoG CF-5/20 to evaluate their structural and antimicrobial properties. Overnight microbial cultures were adjusted to 2.8 × 109 colony-forming units (cfu) mL-1 in Mueller Hinton broth and growth rates of Pseudomonas aeruginosa PAO1 and Staphylococcus aureus 1061A monitored for 24 h in CNF dispersions sterilized by γ-irradiation. Two CNF formulations were prepared (20 g m-2) with CNF as air-dried films or freeze-dried aerogels, with or without incorporation of an antimicrobial alginate oligosaccharide (OligoG CF-5/20) as a surface coating or bionanocomposite, respectively. The materials were structurally characterized by scanning electron microscopy (SEM) and laser profilometry (LP). The antimicrobial properties of the formulations were assessed using single- and mixed-species biofilms grown on the materials and analyzed using LIVE/DEAD staining with confocal laser scanning microscopy (CLSM) and COMSTAT software. OligoG-CNF suspensions significantly decreased the growth of both bacterial strains at OligoG concentrations >2.58% (P < 0.05). SEM showed that aerogel-OligoG bionanocomposite formulations had a more open three-dimensional structure, whereas LP showed that film formulations coated with OligoG were significantly smoother than untreated films or films incorporating PEG400 as a plasticizer (P < 0.05). CLSM of biofilms grown on films incorporating OligoG demonstrated altered biofilm architecture, with reduced biomass and decreased cell viability. The OligoG-CNF formulations as aerogels or films both inhibited pyocyanin production (P < 0.05). These novel CNF formulations or bionanocomposites were able to modify bacterial growth, biofilm development, and virulence factor production in vitro. These data support the potential of OligoG and CNF bionanocomposites for use in biomedical applications where prevention of infection or biofilm growth is required.

  • 21.
    Jacobs, Anna
    et al.
    STFI.
    Dahlman, Olof
    STFI.
    Characterization of the Molar Masses of Hemicelluloses from Wood and Pulps Employing Size Exclusion Chromatography and Matrix-Assisted Laser Desorption Ionization Time-of-Flight Mass Spectrometry2001In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 2, no 3, p. 894-905Article in journal (Refereed)
  • 22.
    Jacobs, Anna
    et al.
    STFI.
    Larsson, Per Tomas
    STFI.
    Dahlman, Olof
    STFI.
    Distribution of Uronic Acids in Xylans from Various Species of Soft- and Hardwood As Determined by MALDI Mass Spectrometry2001In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 2, no 3, p. 979-990Article in journal (Refereed)
  • 23.
    Johansson, Emma
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Processum.
    Lundström, Lisa
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Processum.
    Norgren, Magnus
    Wågberg, Lars
    Adsorption behavior and adhesive properties of biopolyelectrolyte multilayers formed from cationic and anionic starch2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 7, p. 1768-1776Article in journal (Refereed)
    Abstract [en]

    Cationic starch (D.S. 0.065) and anionic starch (D.S. 0.037) were used to form biopolyelectrolyte multilayers. The influence of the solution concentration of NaCl on the adsorption of starch onto silicon oxide substrates and on the formation of multilayers was investigated using stagnation point adsorption reflectometry (SPAR) and quartz crystal microbalance with dissipation (QCM-D). The wet adhesive properties of the starch multilayers were examined by measuring pull-off forces with the AFM colloidal probe technique. It was shown that polyelectrolyte multilayers (PEM) can be successfully constructed from cationic starch and anionic starch at electrolyte concentrations of 1 mM NaCl and 10 mM NaCl. The water content of the PEMs was approximately 80% at both electrolyte concentrations. However, the thickness of the PEMs formed at 10 mM NaCl was approximately twice the thickness formed at 1 mM NaCl. The viscoelastic properties of the starch PEMs, modeled as Voigt elements, were dependent on the polyelectrolyte that was adsorbed in the outermost layer. The PEMs appeared to be more rigid when capped by anionic starch than when capped by cationic starch. The wet adhesive pull-off forces increased with layer number and were also dependent on the polyelectrolyte adsorbed in the outermost layer. Thus, starch PEM treatment has a large potential for increasing the adhesive interaction between solid substrates to levels higher than can be reached by a single layer of cationic starch. © 2009 American Chemical Society.

  • 24. Johansson, JÅ
    et al.
    Halthur, T
    YKI – Ytkemiska institutet.
    Herranen, M
    Söderberg, L
    Elofsson, U
    YKI – Ytkemiska institutet.
    Hilborn, J
    Build-up of collagen and hyaluronic acid polyelectrolyte multilayers2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, p. 1353-1359Article in journal (Refereed)
    Abstract [en]

    We have used a novel polyelectrolyte multilayer (PEM) coating consisting of the polyelectrolytes collagen and hyaluronic acid. The build-up by the layer-by-layer deposition technique is outlined by ex situ and in situ ellipsometric measurements. When collagen was added the thickness of the PEM was increased and the refractive index was decreased. Corresponding but opposite effects were noted when hyaluronic acid was added. These changes are considered to be explained by a diffusion mechanism. It was also found that the PEM layers were unstable at physiological pH. However, by crosslinking using N-(3-Di-methylaminopropyl)-N0-ethylcarbodiimide together with N-hydroxysuccinimide a stable PEM layer resulted. These tissue friendly PEM layers are expected to have a great impact in the design of artificial extra cellular matrices. Also, the insertion of fluorescence labels demonstrates the potential for incorporation of other functionalities

  • 25.
    Karlsson, Rose-Marie Pernilla
    et al.
    KTH Royal Institute of Technology, Sweden.
    Larsson, Per Tomas
    RISE - Research Institutes of Sweden, Bioeconomy, Biorefinery and Energy. KTH Royal Institute of Technology, Sweden.
    Hansson, Per
    Uppsala University, Sweden.
    Wågberg, Lars
    KTH Royal Institute of Technology, Sweden.
    Thermodynamics of the Water-Retaining Properties of Cellulose-Based Networks2019In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 20, no 4, p. 1603-1612Article in journal (Refereed)
    Abstract [en]

    Noncrystalline cellulose-based gel beads were used as a model material to investigate the effect of osmotic stress on a cellulosic network. The gel beads were exposed to osmotic stress by immersion in solutions with different concentrations of high molecular mass dextran and the equilibrium dimensional change of the gel beads was studied using optical microscopy. The volume fraction of cellulose was calculated from the volume of the gel beads in dextran solutions and their dry content and the relation between the cellulose volume fraction and the total osmotic pressure was thus obtained. The results show that the contribution to the osmotic pressure from counterions increases the water-retaining capacity of the beads at high osmotic pressures but also that the main factor controlling the gel bead collapse at high osmotic strains is the resistance to the deformation of the polymer chain network within the beads. Furthermore, the osmotic pressure associated with the deformation of the polymer network, which counteracts the deswelling of the beads, could be fitted to the Wall model indicating that the response of the cellulose polymer networks was independent of the charge of the cellulose. The best fit to the Wall model was obtained when the Flory-Huggins interaction parameter (χ) of the cellulose-water system was set to 0.55-0.60, in agreement with the well-established insolubility of high molecular mass β-(1,4)-d-glucan polymers in water.

  • 26. Kuktaite, R.
    et al.
    Plivelic, T.S.
    Cerenius, Y.
    Hedenqvist, M.S.
    Gällstedt, M.
    RISE, Innventia.
    Marttila, S.
    Ignell, R.
    Popineau, Y.
    Tranquet, O.
    Shewry, P.R.
    Johansson, E.
    Structure and morphology of wheat gluten films: From polymeric protein aggregates toward superstructure arrangements2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 5, p. 1438-1448Article in journal (Refereed)
  • 27. Lofgren, C.
    et al.
    Guillotin, S.
    Evenbratt, H.
    Schols, H.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Effects of calcium, pH, and blockiness on kinetic rheological behavior and microstructure of HM pectin gels2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 2, p. 646-652Article in journal (Refereed)
    Abstract [en]

    The kinetic behavior during gel formation and the microstructure of 0.75% high methoxyl (HM) pectin gels in 60% sucrose have been investigated by oscillatory measurements and transmission electron microscopy for three comparable citrus pectin samples differing in their degree of blockiness (DB). Ca2+ addition at pH 3.0 resulted in faster gel formation and a lower storage modulus after 3 h for gels of the blockwise pectin A. For gels of the randomly esterified pectin B, the Ca2+ addition resulted in faster gel formation and a higher storage modulus at pH 3.0. At pH 3.5, both pectins A and B were reinforced by the addition of Ca2+. In the absence of Ca2+, the shortest gelation time was obtained for the sample with the highest DB. Microstructural characterization of the gel network, 4 and 20 h after gel preparation, showed no visible changes on a nanometer scale. The microstructure of pectins A and B without Ca2+ was similar, whereas the presence of Ca2+ in pectin A resulted in an inhomogeneous structure. © 2005 American Chemical Society.

  • 28. Lofgren, C.
    et al.
    Guillotin, S.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Microstructure and kinetic rheological behavior of amidated and nonamidated LM pectin gels2006In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 7, no 1, p. 114-121Article in journal (Refereed)
    Abstract [en]

    The microstructure, kinetics of gelation, and rheological properties have been investigated for gels of nonamidated pectin (C30), amidated pectin (G), and saponified pectin (sG) at different pH values, both with and without sucrose. The low-methoxyl (LM) pectin gels were characterized in the presence of Ca2+ by oscillatory measurements and transmission electron microscopy (TEM). The appearance of the gel microstructure varied with the pH, the gel structure being sparse and aggregated at pH 3 but dense and somewhat entangled at pH 7. During gel formation of pectins G and C30 at pH 3 there was a rapid increase in G? initially followed by a small increase with time. At pH 7 G? increased very rapidly at first but then remained constant. The presence of sucrose influenced neither the kinetic behavior nor the microstructure of the gels but strongly increased the storage modulus. Pectins G and C30 showed large variations in G? at pH values 3, 4, 5, and 7 in the presence of sucrose, and the maximum in G? in the samples occurred at different pH values. Due to its high Ca2+ sensitivity, pectin sG had a storage modulus that was about 50 times higher than that of its mother pectin G at pH 7. © 2006 American Chemical Society.

  • 29. Lofgren, C.
    et al.
    Walkenström, Pernilla
    SIK – Institutet för livsmedel och bioteknik.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Microstructure and rheological behavior of pure and mixed pectin gels2002In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 6, p. 1144-1153Article in journal (Refereed)
    Abstract [en]

    The microstructure and the rheological properties of pure HM (high methoxyl) and LM (low methoxyl) pectin gels and of mixed HM/LM pectin gels have been investigated. Gel formation of either the HM or LM pectin, or both, was initiated in the mixed gels by varying the sucrose and Ca 2+ content. The microstructure was characterized by transmission electron microscopy, light microscopy, and confocal laser scanning microscopy. HM and LM pectin gels showed aggregated networks with large pores around 500 nm and network strands of similar character. Small differences could be found, such as a more inhomogeneous LM pectin network with shorter and more branched strands of flexible appearance. LM pectin also formed a weak gel in 60% sucrose in the absence of calcium. A highly inhomogeneous mixed gel structure was formed in the presence of 60% sucrose and Ca 2+ ions, which showed large synergistic effects in rheological properties. Its formation was explained by the behavior of the corresponding pure gels. In the presence of 60% sucrose alone, a homogeneous, fine-stranded mixed network was formed, which showed weak synergistic effects. It is suggested that LM pectin interacts with HM pectin during gel formation, thereby hindering secondary aggregation leading to the aggregated networks observed for the pure gels.

  • 30.
    Loren, Niklas
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Shtykova, L.
    Kidman, Siw
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Jarvoll, P.
    Nyden, M.
    Hermansson, Ann-Marie
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Dendrimer diffusion in ?-carrageenan gel structures2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 2, p. 275-284Article in journal (Refereed)
    Abstract [en]

    The effect of the ?-carrageenan concentration on gel microstructure and self-diffusion of polyamideamine dendrimers has been determined by transmission electron microscopy (TEM), image analysis, and nuclear magnetic resonance (NMR) diffusometry. Different salt conditions of KCl, NaCl, and mixtures thereof allowed for formation of significantly different microstructures. The ?-carrageenan concentrations were varied between 0.25 and 3.0 w/w% for a salt mixture containing 20 mM KCl and 200 mM NaCl gels and between 0.5 and 4.0 w/w% for 250 mM NaCl gels. Furthermore, the effect of potassium ion concentration on the gel structure and the dendrimer diffusion rate was determined. The potassium ion concentration was varied between 20 mM KCl and 200 mM KCl. Two different dendrimer generations with significant difference in size were used: G2 and G6. Dendrimers were found to be sensitive probes for determination of the effect of the gel microstructure on molecular diffusion rate. A qualitative comparison between TEM micrographs, NMR diffusometry data and image analysis showed that the gel structure has a large impact on the dendrimers diffusion in ?-carrageenan gels. It was found that diffusion was strongly influenced by the ?-carrageenan concentration and the dendrimer generation. Small voids in the gel network gave strongly reduced diffusion. Image analysis revealed that the interfacial area between the gel network and the surrounding water phase correlated well with the dendrimer diffusion. © 2009 American Chemical Society.

  • 31.
    Mansel, Bradley W.
    et al.
    Massey University, New Zealand; Macdiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.
    Chu, Che-Yi
    National Tsing-Hua University, Taiwan; National Synchrotron Radiation Research Centre, Taiwan.
    Leis, Andrew
    CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Hemar, Yacine
    University of Auckland, New Zealand.
    Chen, Hsin-Lung
    National Tsing-Hua University, Taiwan.
    Lundin, Leif
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Food and Bioscience. CSIRO Commonwealth Scientific and Industrial Research Organisation, Australia.
    Williams, Martin A. K.
    Massey University, New Zealand; Macdiarmid Institute for Advanced Materials and Nanotechnology, New Zealand.
    Zooming in: Structural Investigations of Rheologically Characterized Hydrogen-Bonded Low-Methoxyl Pectin Networks2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 10, p. 3209-3216Article in journal (Refereed)
    Abstract [en]

    Self-assembled hydrogen-bonded networks of the polysaccharide pectin, a mechanically functional component of plant cell walls, have been of recent interest as biomimetic exemplars of physical gels, and the microrheological and strain-stiffening behaviors have been previously investigated. Despite this detailed rheological characterization of preformed gels, little is known about the fundamental arrangement of the polymers into cross-linking junction zones, the size of these bonded regions, and the resultant network architecture in these hydrogen-bonded materials, especially in contrast to the plethora of such information available for their well-known calcium-assembled counterparts. In this work, in concert with pertinent rheological measurements, an in-depth structural study of the hydrogen-bond-mediated gelation of pectins is provided. Gels were realized by using glucona-delta-lactone to decrease the pH of solutions of pectic polymers that had a (blockwise) low degree of methylesterification. Small-angle X-ray scattering and transmission electron microscopy were utilized to access structural information on length scales on the order of nanometers to hundreds of nanometers, while complementary mechanical properties were measured predominantly using small amplitude oscillatory shear rheology.

  • 32.
    Muneer, Faraz
    et al.
    SLU Swedish University of Agricultural Sciences, Sweden.
    Andersson, Mariette
    SLU Swedish University of Agricultural Sciences, Sweden.
    Koch, Kristine
    SLU Swedish University of Agricultural Sciences, Sweden.
    Menzel, Carolin
    SLU Swedish University of Agricultural Sciences, Sweden.
    Hedenqvist, Mikael S.
    KTH Royal Institute of Technology, Sweden.
    Gällstedt, Mikael
    RISE, Innventia.
    Plivelic, Tomás S.
    Lund University, Sweden.
    Kuktaite, Ramune
    SLU Swedish University of Agricultural Sciences, Sweden.
    Nanostructural Morphology of Plasticized Wheat Gluten and Modified Potato Starch Composites: Relationship to Mechanical and Barrier Properties2015In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 16, no 3, p. 695-705Article in journal (Refereed)
    Abstract [en]

    In the present study, we were able to produce composites of wheat gluten (WG) protein and a novel genetically modified potato starch (MPS) with attractive mechanical and gas barrier properties using extrusion. Characterization of the MPS revealed an altered chain length distribution of the amylopectin fraction and slightly increased amylose content compared to wild type potato starch. WG and MPS of different ratios plasticized with either glycerol or glycerol and water were extruded at 110 and 130 °C. The nanomorphology of the composites showed the MPS having semicrystalline structure of a characteristic lamellar arrangement with an approximately 100 Å period observed by small-angle X-ray scattering and a B-type crystal structure observed by wide-angle X-ray scattering analysis. WG has a structure resembling the hexagonal macromolecular arrangement as reported previously in WG films. A larger amount of β-sheets was observed in the samples 70/30 and 30/70 WG-MPS processed at 130 °C with 45% glycerol. Highly polymerized WG protein was found in the samples processed at 130 °C versus 110 °C. Also, greater amounts of WG protein in the blend resulted in greater extensibility (110 °C) and a decrease in both E-modulus and maximum stress at 110 and 130 °C, respectively. Under ambient conditions the WG-MPS composite (70/30) with 45% glycerol showed excellent gas barrier properties to be further explored in multilayer film packaging applications. (Graph presented).

  • 33.
    Nilebäck, Linnea
    et al.
    KTH Royal Institute of Technology, Sweden.
    Hedin, Jesper
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Widhe, Mona
    KTH Royal Institute of Technology, Sweden.
    Floderus, Lotta S
    KTH Royal Institute of Technology, Sweden.
    Krona, Annika
    RISE - Research Institutes of Sweden, Bioscience and Materials, Agrifood and Bioscience.
    Bysell, Helena
    RISE - Research Institutes of Sweden, Bioscience and Materials, Chemistry and Materials.
    Hedhammar, My
    KTH Royal Institute of Technology, Sweden.
    Self-Assembly of Recombinant Silk as a Strategy for ChemicalFree Formation of Bioactive Coatings – a Real-Time Study2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 3, p. 846-854Article in journal (Refereed)
    Abstract [en]

    Functionalization of biomaterials with biologically active peptides can improve their performance after implantation. By genetic fusion to self-assembling proteins, the functional peptides can easily be presented on different physical formats. Herein, a chemical-free coating method based on self-assembly of the recombinant spider silk protein 4RepCT is described and used to prepare functional coatings on various biomaterial surfaces. The silk assembly was studied in real-time, revealing occurrence of continuous assembly of silk proteins onto surfaces and formation of nanofibrillar structures. The adsorbed amounts and viscoelastic properties were evaluated, and the coatings were shown to be stable against wash with hydrogen chloride, sodium hydroxide, and ethanol. Titanium, stainless steel, and hydroxyapatite were coated with silk fused to an antimicrobial peptide or a motif from fibronectin. Human primary cells cultured on the functional silk coatings show good cell viability and proliferation, implying potential to improve implant performance and acceptance by the body.

  • 34.
    Nordgren, N
    et al.
    YKI – Ytkemiska institutet.
    Eklöf, J
    Zhou, Q
    Brumer, H
    Rutland, MW
    YKI – Ytkemiska institutet.
    Top-down grafting of xyloglucan to gold monitored by QCM-D and AFM: Enzymatic activity and interactions with cellulose2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 3, p. 942-948Article in journal (Refereed)
    Abstract [en]

    This study focuses on the manufacture and characterization of model surfaces consisting of end-grafted xyloglucan (XG), a naturally occurring polysaccharide, onto a gold substrate. The now well-established XET-technology was utilized for enzymatic incorporation of a thiol moiety at one end of the xyloglucan backbone. This functionalized macromolecule was subsequently top-down grafted to gold, forming a thiol-bonded xyloglucan brushlike layer. The grafting was monitored in situ with QCM-D, and a significant difference in the adsorbed/grafted amount between unmodified xyloglucan and the thiol-functionalized polymer was observed. The grafted surface was demonstrated to be accessible to enzyme digestion using the plant endo-xyloglucanase TmNXG1. The nanotribological properties toward cellulose of the untreated crystal, brush-modified surface, and enzyme-exposed surfaces were compared with a view to understanding the role of xyloglucan in friction reduction. Friction coefficients obtained by the AFM colloidal probe technique using a cellulose functionalized probe on the xyloglucan brush showed an increase of a factor of 2 after the enzyme digestion, and this result is interpreted in terms of surface roughness. Finally, the brush is shown to exhibit binding to cellulose despite its highly oriented nature.

  • 35.
    Nordgren, N
    et al.
    YKI – Ytkemiska institutet.
    Eronen, P
    Osterberg, M
    Laine, J
    Rutland, MW
    YKI – Ytkemiska institutet.
    Mediation of the nanotribological properties of cellulose by chitosan adsorption2009In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 10, no 3, p. 645-650Article in journal (Refereed)
    Abstract [en]

    Cellulosic model surfaces functionalized with chitosan, a naturally occurring cationic biomacromolecule, by in situ adsorption have been studied with an atomic force microscope (AFM) in colloidal probe configuration. The interaction forces on approach and separation, as well as the nanotribological properties, were shown to be highly pH-dependent, and a significant difference in the behavior was seen before and after chitosan adsorption. In general, all forces on approach showed a highly repulsive interaction at shorter distances due to deformation of the probe. At high pH, before chitosan adsorption, a long-range electrostatic repulsion was observed, consistent with DLVO theory. However, at low pH no electrostatic contribution was found before adsorption, probably due to charge neutralization of carboxyl groups. After chitosan adsorption, repulsive forces acting over a much longer distance than predicted by DLVO theory were present at low pH. This effect was ascribed to chain extension of the chitosan species of which the magnitude and the range of the force increased dramatically with higher charge at low pH. In all cases, a typical saw-tooth patterned adhesion was present, with pull-off events occurring at different separations. The frequency of these events after chitosan adsorption was greatly increased at longer distances. Additionally, the adsorbed chitosan markedly reduced the friction, where the largest effect was a 7-fold decrease of the friction coefficient observed at low pH

  • 36.
    Nyström, Lina
    et al.
    Uppsala University, Sweden.
    Nordström, Randi
    Uppsala University, Sweden.
    Bramhill, Jane
    University of Manchester, UK.
    Saunders, Brian R.
    University of Manchester, UK.
    Álvarez-Asencio, Rubén
    KTH Royal Institute of Technology, Sweden; IMDEA Nanoscience, Spain.
    Rutland, Mark W.
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor, Life Science. KTH Royal Institute of Technology, Sweden.
    Malmsten, Martin
    Uppsala University, Sweden.
    Factors affecting peptide interactions with surface-bound microgels2016In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 17, no 2, p. 669-678Article in journal (Refereed)
    Abstract [en]

    Effects of electrostatics and peptide size on peptide interactions with surface-bound microgels were investigated with ellipsometry, confocal microscopy, and atomic force microscopy (AFM). Results show that binding of cationic poly-l-lysine (pLys) to anionic, covalently immobilized, poly(ethyl acrylate-co-methacrylic acid) microgels increased with increasing peptide net charge and microgel charge density. Furthermore, peptide release was facilitated by decreasing either microgel or peptide charge density. Analogously, increasing ionic strength facilitated peptide release for short peptides. As a result of peptide binding, the surface-bound microgels displayed pronounced deswelling and increased mechanical rigidity, the latter quantified by quantitative nanomechanical mapping. While short pLys was found to penetrate the entire microgel network and to result in almost complete charge neutralization, larger peptides were partially excluded from the microgel network, forming an outer peptide layer on the microgels. As a result of this difference, microgel flattening was more influenced by the lower Mw peptide than the higher. Peptide-induced deswelling was found to be lower for higher Mw pLys, the latter effect not observed for the corresponding microgels in the dispersed state. While the effects of electrostatics on peptide loading and release were similar to those observed for dispersed microgels, there were thus considerable effects of the underlying surface on peptide-induced microgel deswelling, which need to be considered in the design of surface-bound microgels as carriers of peptide loads, for example, in drug delivery or in functionalized biomaterials.

  • 37. Olsson, C.
    et al.
    Frigard, T.
    Andersson, R.
    Hermansson, Ann-Marie
    SIK – Institutet för livsmedel och bioteknik.
    Effects of amylopectin structure and molecular weight on microstructural and rheological properties of mixed beta-lactoglobulin gels2003In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 4, no 5, p. 1400-1409Article in journal (Refereed)
    Abstract [en]

    Nongelling amylopectin fractions from potato and barley have been used to form mixed ?-lactoglobulin gels. The amylopectin fractions were produced by varying the time of ?-amylase hydrolysis followed by sequential ethanol precipitation. The molecular weights, radius of gyration, chain length distribution, and viscosity of the fractions were established. The mixed gels were analyzed theologically with dynamic mechanical analysis in shear and microstructurally with light microscopy, transmission electron microscopy, and nuclear magnetic resonance spectroscopy. The result of the gel studies clearly showed that small differences in the molecular weight of amylopectins have a significant influence on the kinetics of protein aggregation and thereby on the gel microstructure and the rheological behavior of the gel. Both an increase in the molecular weight and a higher concentration of amylopectins resulted in a more open protein network structure, with thicker strands of larger and more close-packed ?-lactoglobulin clusters, which showed a larger storage modulus. The transmission electron micrographs revealed that degraded amylopectins were enclosed inside the protein clusters in the mixed gels, whereas nondegraded amylopectin was only found outside the protein clusters. The volume-weighted mean value of the molecular weight of the amylopectins was found to vary between 3.2 × 10 4 and 5.0 × 10 7 Da and the ratio of gyration between 14 and 61 nm. The maximum in chain length distribution was generally somewhat distributed toward longer chain lengths for potato compared to barley, but the differences in chain length distribution were minor compared to those seen in the molecular weight and ratio of gyration between the fractions.

  • 38. Persson, PV
    et al.
    Hafren, J
    Fogden, A
    YKI – Ytkemiska institutet.
    Daniel, G
    Iversen, T
    Silica nanocasts of wood fibres: A study of cell wall accessibility and structure2004In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 5, p. 1097-1101Article in journal (Refereed)
    Abstract [en]

    The porosity and the available surface area of a lignocellulosic fiber can influence the accessibility and reactivity in derivatization and modification reactions because the porous cell-wall network determines the upper size limit for molecules that can penetrate and react with the interior of the wall. To obtain information concerning the accessibility of the porous cell wall of wood fibers, surfactant-templated sol-gel mineralization has been examined. Wood and kraft pulp samples of Norway spruce were impregnated with a silica sol-gel and subsequently heated (calcined) and transformed into structured mesoporous silica. Microscopy studies (environmental scanning electron microscopy, transmission electron microsopy, TEM) on the silica casts showed that the three-dimensional architecture of the wood and pulp fiber cell wall was revealed down to the nanometer level. Image analysis of TEM micrographs of silica fragments from the never-dried pulp revealed complete infiltration of the cell-wall voids and microcavities (mean pore width 4.7 ± 2 nm) by the sol-gel and the presence of cellulose fibrils with a width of 3.6 ± 1 nm. Cellulose fibrils of the same width as that shown by image analysis were also identified by nitrogen adsorption measurements of the pore size distribution in the replicas.

  • 39. Petersson, M.
    et al.
    Loren, Niklas
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Characterization of phase separation in film forming biopolymer mixtures2005In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 6, no 2, p. 932-941Article in journal (Refereed)
    Abstract [en]

    Enhanced, tailor-made films can be achieved by combining the good gas barrier of the hydrophilic high amylose maize starch (hylon) with the water resistance of the hydrophobic protein zein. Two polymers are not always miscible in solution, and the phase separation behavior of the mixture is therefore important for the final film structure and its properties. Phase separation of a mixture of these two biopolymers was induced either by cooling, which was observed as growing droplets of the hylon phase which in some cases also formed small aggregates, or by solvent evaporation and studied in real-time in a confocal laser scanning microscope. Solvent evaporation had a much stronger effect on phase separation. During the early stage of phase separation, hylon formed large aggregates and subsequently smaller droplets coalesced with other droplets or large hylon aggregates. The later part of the separation seemed to take place through spinodal decomposition. © 2005 American Chemical Society.

  • 40.
    Rashad, Ahmad
    et al.
    University of Bergen, Norway.
    Mohamed-Ahmed, Samih
    University of Bergen, Norway.
    Ojansivu, Miina
    University of Bergen, Norway; University of Tampere, Finland.
    Berstad, Kaia
    University of Bergen, Norway.
    Yassin, Mohammad
    University of Bergen, Norway.
    Kivijärvi, Tove
    KTH Royal Institute of Technology, Sweden.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Mustafa, Kamal
    University of Bergen, Norway.
    Coating 3D Printed Polycaprolactone Scaffolds with Nanocellulose Promotes Growth and Differentiation of Mesenchymal Stem Cells2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 11, p. 4307-4319Article in journal (Refereed)
    Abstract [en]

    3D printed polycaprolactone (PCL) has potential as a scaffold for bone tissue engineering, but the hydrophobic surface may hinder optimal cell responses. The surface properties can be improved by coating the scaffold with cellulose nanofibrils material (CNF), a multiscale hydrophilic biocompatible biomaterial derived from wood. In this study, human bone marrow-derived mesenchymal stem cells were cultured on tissue culture plates (TCP) and 3D printed PCL scaffolds coated with CNF. Cellular responses to the surfaces (viability, attachment, proliferation, and osteogenic differentiation) were documented. CNF significantly enhanced the hydrophilic properties of PCL scaffolds and promoted protein adsorption. Live/dead staining and lactate dehydrogenase release assays confirmed that CNF did not inhibit cellular viability. The CNF between the 3D printed PCL strands and pores acted as a hydrophilic barrier, enhancing cell seeding efficiency, and proliferation. CNF supported the formation of a well-organized actin cytoskeleton and cellular production of vinculin protein on the surfaces of TCP and PCL scaffolds. Moreover, CNF-coated surfaces enhanced not only alkaline phosphatase activity, but also collagen Type-I and mineral formation. It is concluded that CNF coating enhances cell attachment, proliferation, and osteogenic differentiation and has the potential to improve the performance of 3D printed PCL scaffolds for bone tissue engineering.

  • 41.
    Rashad, Amad
    et al.
    University of Bergen, Norway.
    Mustafa, Kamal
    University of Bergen, Norway.
    Heggset, Ellinor B
    RISE - Research Institutes of Sweden, Bioeconomy, PFI.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Cytocompatibility of Wood-Derived Cellulose Nanofibril Hydrogels with Different Surface Chemistry2017In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 18, no 4, p. 1238-1248Article in journal (Refereed)
    Abstract [en]

    The current study aims to demonstrate the influence of the surface chemistry of wood-derived cellulose nanofibril (CNF) hydrogels on fibroblasts for tissue engineering applications. TEMPO-mediated oxidation or carboxymethylation pretreatments were employed to produce hydrogels with different surface chemistry. This study demonstrates the following: first, the gelation of CNF with cell culture medium and formation of stable hydrogels with improved rheological properties; second, the response of mouse fibroblasts cultured on the surface of the hydrogels or sandwiched within the materials with respect to cytotoxicity, cell attachment, proliferation, morphology, and migration. Indirect cytotoxicity tests showed no toxic effect of either hydrogel. The direct contact with the carboxymethylated hydrogel adversely influenced the morphology of the cells and limited their spreading, while typical morphology and spreading of cells were observed with the TEMPO-oxidized hydrogel. The porous fibrous structure may be a key to cell proliferation and migration in the hydrogels.

  • 42. Rindlav-Westling, A.
    et al.
    Stading, Mats
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Sveriges tekniska forskningsinstitut, SIK – Institutet för livsmedel och bioteknik.
    Gatenholm, P.
    Crystallinity and morphology in films of starch, amylose and amylopectin blends2002In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 3, no 1, p. 84-91Article in journal (Refereed)
    Abstract [en]

    Films of potato starch, amylose, and amylopectin and blends thereof were prepared by solution casting and examined using X-ray diffraction, light microscopy, transmission electron microscopy, and differential scanning calorimetry. Amylose films had a relative crystallinity of about 30% whereas amylopectin films were entirely amorphous. Blending of amylose and amylopectin resulted in films with a considerably higher degree of crystallinity than could be predicted. This is explained by cocrystallization between amylose and amylopectin and possibly by crystallization of amylopectin. The crystallized material gave rise to an endotherm detected with differential scanning calorimetry. The enthalpy and peak temperature of the transition also increased as the water content decreased. When the amylose proportion in the blends was low, separate phases of amylose and amylopectin were observed by light microscopy. At higher amylose proportions, however, the phase separation was apparently prevented by amylose gelation and the formation of a continuous amylose network. The amylose network in the films, observed with transmission electron microscopy, consisted of stiff strands and open pores and became less visible as the amylose proportion decreased. The water content of the films was dependent on the microstructure and the crystallinity.

  • 43.
    Rutland, Mark
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Nanobiocomposite adhesion: Role of graft length and temperature in a hybrid biomimetic approach2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 14, no 4, p. 1003-1009Article in journal (Refereed)
  • 44. Saadatmand, S.
    et al.
    Edlund, U.
    Albertsson, A.-C.
    Danielsson, S.
    RISE, Innventia.
    Dahlman, O.
    RISE, Innventia.
    Karlström, K.
    RISE, Innventia.
    Turning hardwood dissolving pulp polysaccharide residual material into barrier packaging2013In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 8, p. 2929-2936Article in journal (Refereed)
  • 45.
    Stiernstedt, J
    et al.
    YKI – Ytkemiska institutet.
    Brumer III, H
    Zhou, Q
    Teeri, TT
    Rutland, MW
    YKI – Ytkemiska institutet.
    Friction between cellulose surfaces and the effect of and xyloglucan adsorption2006In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 7, p. 2147-2153Article in journal (Refereed)
    Abstract [en]

    The forces and friction between cellulose spheres have been measured in the absence and presence of xyloglucan using an atomic force microscope. The forces between cellulose are monotonically repulsive with negligible adhesion after contact is achieved. The friction coefficient is observed to be unusually high in comparison with other nanotribological systems. We have confirmed that xyloglucan adsorbs strongly to cellulose, which results in a much stronger adhesion, which is dependent on the time the surfaces are in contact. Xyloglucan also increases the repulsion on approach of the cellulose surfaces, and the friction is markedly reduced. The apparently incompatible observations of decreased friction in combination with increased adhesion fulfills many of the necessary criteria for a papermaking additive.

  • 46. Tanpichai, S.
    et al.
    Quero, F.
    Nogi, M.
    Yano, H.
    Young, R.J.
    Lindström, T.
    RISE, Innventia.
    Sampson, W.W.
    Eichhorn, S.J.
    Effective young's modulus of bacterial and microfibrillated cellulose fibrils in fibrous networks2012In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 5, p. 1340-1349Article in journal (Refereed)
  • 47.
    Thorvaldsson, Anna
    et al.
    RISE, Swerea, Swerea IVF.
    Stenhamre, H.
    Chalmers University of Technology.
    Gatenholm, P.
    Chalmers University of Technology.
    Walkenström, Pernilla
    RISE, Swerea, Swerea IVF.
    Electrospinning of highly porous scaffolds for cartilage regeneration2008In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 9, no 3, p. 1044-1049Article in journal (Refereed)
    Abstract [en]

    This study presents a new innovative method where electrospinning is used to coat single microfibers with nanofibers. The nanofiber-coated microfibers can be formed into scaffolds with the combined benefits of tailored porosity for cellular infiltration and nanostructured surface morphology for cell growth. The nanofiber coating is obtained by using a grounded collector rotating around the microfiber, to establish an electrical field yet allow collection of nanofibers on the microfiber. A Teflon tube surrounding the fibers and collector is used to force the nanofibers to the microfiber. Polycaprolactone nanofibers were electrospun onto polylactic acid microfibers and scaffolds of 95 and 97% porosities were made. Human chondrocytes were seeded on these scaffolds and on reference scaffolds of purely nanofibers and microfibers. Thereafter, cellular infiltration was investigated. The results indicated that scaffold porosity had great effects on cellular infiltration, with higher porosity resulting in increased infiltration, thereby confirming the advantage of the presented method. © 2008 American Chemical Society.

  • 48.
    Torstensen, Jonathan Ø
    et al.
    NTNU Norwegian University of Science and Technology, Norway.
    Liu, Ming
    North Carolina State University, USA.
    Jin, Soo-Ah
    North Carolina State University, USA.
    Deng, Liyuan
    NTNU Norwegian University of Science and Technology, Norway.
    Hawari, Ayman I
    North Carolina State University, USA.
    Syverud, Kristin
    RISE - Research Institutes of Sweden, Bioeconomy, PFI. NTNU Norwegian University of Science and Technology, Norway.
    Spontak, Richard J
    North Carolina State University, USA.
    Gregersen, Øyvind W
    NTNU Norwegian University of Science and Technology, Norway.
    Swelling and Free-Volume Characteristics of TEMPO-Oxidized Cellulose Nanofibril Films.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 3, p. 1016-1025Article in journal (Refereed)
    Abstract [en]

    Cellulose nanofibrils (CNFs) are becoming increasingly ubiquitous in diverse technologies requiring sustainable nanoscale species to form or modify films. The objective of the present study is to investigate the swelling behavior and accompanying free volume of self-standing TEMPO-oxidized (TO) CNF films in the presence of water vapor. For this purpose, we have performed time-resolved swelling experiments on films, prepared according to different experimental protocols, at 90% relative humidity (RH) and ambient temperature. Corresponding free-volume characteristics are elucidated by positron annihilation lifetime spectroscopy (PALS) conducted at ambient temperature and several RH levels. Increasing the drying temperature of the films (from ambient to 50 °C) is observed to promote an increase in film density, which serves to reduce bulk swelling. These elevated drying temperatures likewise cause the free-volume pore size measured by PALS to decrease, while the corresponding total free-volume fraction remains nearly constant. Similarly, dispersion of TO-CNF into aqueous suspensions by ultrasonication prior to film formation increases both the total free-volume fraction and pore size but reduces the size of individual nanofibrils with little net change in bulk swelling. The swelling and concurrent free-volume measurements reported here generally reveal an increase in the free volume of TO-CNF films with increasing RH.

  • 49. Wang, M.
    et al.
    Olszewska, A.
    Walther, A.
    Malho, J.-M.
    Schacher, F.H.
    Ruokolainen, J.
    Ankerfors, M.
    RISE, Innventia.
    Laine, J.
    Berglund, L.A.
    Österberg, M.
    Ikkala, O.
    Colloidal ionic assembly between anionic native cellulose nanofibrils and cationic block copolymer micelles into biomimetic nanocomposites2011In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, no 6, p. 2074-2081Article in journal (Refereed)
  • 50.
    Yang, Xuan
    et al.
    KTH Royal Institute of Technology, Sweden.
    Berthold, Fredrik
    RISE - Research Institutes of Sweden, Bioeconomy, Biobased Materials.
    Berglund, Lars A
    KTH Royal Institute of Technology, Sweden.
    Preserving Cellulose Structure: Delignified Wood Fibers for Paper Structures of High Strength and Transparency.2018In: Biomacromolecules, ISSN 1525-7797, E-ISSN 1526-4602, Vol. 19, no 7, p. 3020-3029Article in journal (Refereed)
    Abstract [en]

    To expand the use of renewable materials, paper products with superior mechanical and optical properties are needed. Although beating, bleaching, and additives are known to improve industrially produced Kraft pulp papers, properties are limited by the quality of the fibers. While the use of nanocellulose has been shown to significantly increase paper properties, the current cost associated with their production has limited their industrial relevance. Here, using a simple mild peracetic acid (PAA) delignification process on spruce, we produce hemicellulose-rich holocellulose fibers (28.8 wt %) with high intrinsic strength (1200 MPa for fibers with microfibrillar angle smaller than 10°). We show that PAA treatment causes less cellulose/hemicellulose degradation and better preserves cellulose nanostructure in comparison to conventional Kraft pulping. High-density holocellulose papers with superior mechanical properties (Young's modulus of 18 GPa and ultimate strength of 195 MPa) are manufactured using a water-based hot-pressing process, without the use of beating or additives. We propose that the preserved hemicelluloses act as "glue" in the interfiber region, improving both mechanical and optical properties of papers. Holocellulose fibers may be affordable and applicable candidates for making special paper/composites where high mechanical performance and/or optical transmittance are of interest.

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