Wallenberg Wood Science Center

Göteborg, Sweden

Wallenberg Wood Science Center

Göteborg, Sweden
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Possibly the strongest hybrid silk fibers yet have been created by scientists in Sweden using all renewable resources. Combining spider silk proteins with nanocellulose from wood, the process offers a low-cost and scalable way to make bioactive materials for a wide range of medical uses. Published in ACS Nano by researchers from KTH Royal Institute of Technology in Stockholm, the technique brings together the structural and mechanical performance of inexpensive cellulose nanofibrils with the medicinal properties of spider silk, which is difficult and expensive to fabricate on a larger scale. The bioactive properties of spider silk have been known for centuries. In ancient Rome, spider webs were used to dress soldiers' battle wounds. But producing large scale amounts of spider silk material today has proven an expensive process, which often relies on fossil-based sources. KTH Researcher My Hedhammar says that by comparison, wood-based nanocellulose is cheap and sustainable. Furthermore, the technique of combining it with only small amounts of spider silk protein yields a biofunctional material that can be used for such medical purposes as promoting cell growth. "The strength of the fiber is significantly better than any human-made, silk-based material to our knowledge, and on the same level as what can be found in nature from spiders," says Daniel Söderberg, a researcher with the Wallenberg Wood Science Center at KTH. Today, cellulose nanofibrils obtained from trees receive scientific and commercial attention not only because they are renewable, biodegradeable, virtually non-toxic and available in large volumes, but they also offer outstanding mechanical properties. Söderberg says that the fabricated filament material could potentially be used, for example, as a building-block for ligaments. To make the material, the researchers use what are known as recombinant silk proteins. Rather than using a spider as host, the researchers take the gene encoding the silk protein and combine it with a gene encoding some desired function, such as cell-binding, Hedhammar says. "We transfer this fusion gene to a simple, easily-cultured lab bacteria, which then produces the functionalized silk proteins that can be purified in the lab," she says. "Spider silk fusion proteins are then added to the dispersed cellulose nanofibrils, and thanks to the favorable interactions between the two components, a composite material can be produced." Söderberg says technique uses hydrodynamics to align the fibers' internal structure on the micro- and nano-scale. "When the nanocellulose is aligned in the macroscopic material we can achieve super performance," he says.


Published in ACS Nano by researchers from KTH Royal Institute of Technology in Stockholm, the technique brings together the structural and mechanical performance of inexpensive cellulose nanofibrils with the medicinal properties of spider silk, which is difficult and expensive to fabricate on a large scale. The bioactive properties of spider silk have been known for centuries. In ancient Rome, spider webs were used to dress soldiers' battle wounds. But producing large-scale amounts of spider silk material today is an expensive process that often relies on fossil-based sources. KTH Researcher My Hedhammar says that by comparison, wood-based nanocellulose is cheap and sustainable. Furthermore, the technique of combining it with only small amounts of spider silk protein yields a biofunctional material that can be used for such medical purposes as promoting cell growth. "The strength of the fiber is significantly better than any man-made, silk-based material to our knowledge, and on the same level as what can be found in nature from spiders," says Daniel Söderberg, a researcher with the Wallenberg Wood Science Center at KTH. Today, cellulose nanofibrils obtained from trees receive scientific and commercial attention not only because they are renewable, biodegradable, virtually nontoxic and available in large volumes, but they also offer outstanding mechanical properties. Söderberg says that the fabricated filament material could potentially be used as a building block for ligaments, for example. To make the material, the researchers use what are known as recombinant silk proteins. Rather than using a spider as host, the researchers take the gene encoding the silk protein and combine it with a gene encoding some desired function, such as cell-binding, Hedhammar says. "We transfer this fusion gene to a simple, easily-cultured lab bacteria, which then produces the functionalized silk proteins that can be purified in the lab," she says. "Spider silk fusion proteins are then added to the dispersed cellulose nanofibrils, and thanks to the favorable interactions between the two components, a composite material can be produced." Söderberg says the technique uses hydrodynamics to align the fibers' internal structure on the micro- and nano-scale. "When the nanocellulose is aligned in the macroscopic material, we can achieve high performance," he says. Explore further: Spin doctors say scientists copy spider silk in lab More information: Nitesh Mittal et al. Ultrastrong and Bioactive Nanostructured Bio-Based Composites, ACS Nano (2017). DOI: 10.1021/acsnano.7b02305


News Article | March 17, 2016
Site: www.biosciencetechnology.com

Bioengineers at Wake Forest Institute for Regenerative Medicine have taken a large step, ten years in the making, toward functional 3D bioprinted tissue. The team, led by Anthony Atala, M.D., successfully printed an ear, along with bone and muscle structures using what they call the Integrated Tissue and Organ Printing System (ITOP).   When implanted beneath the skin of mice and rats, the living tissue not only retained its shape over several months, but grew and developed a system of blood vessels. Another advance in 3D bioprinting was presented Wednesday at the American Chemical Society’s national meeting in San Diego, where a team led by Paul Gatenholm, Ph.D., from the Wallenberg Wood Science Center in Sweden reported on their work producing cartilage in an in vivo mouse model.  After 60 days of implantation in mice, the team’s 3D printed combination of polysaccharides, human chondrocytes (cells that build up cartilage), and human mesenchymal stem cells from bone marrow proved successful at encouraging chondrocyte and cartilage production. The findings may one day lead to implants that help heal injured noses, ears and knees. While 3D printing living organs for transplant patients is the ultimate goal of Atala’s group, it is still a long ways off.  Still, Atala’s new technique, detailed Feb. 15 in Nature Biotechnology, overcomes previous hurdles to printing functional tissue that is large enough and strong enough for use in humans. “This novel tissue and organ printer is an important advance in our quest to make replacement tissue for patients,” senior author Atala, said in a statement.  “It can fabricate stable, human-scale tissue of any shape.  With further development, this technology could potentially be used to print living tissue and organ structures for surgical implantation.” Read more: Cotton Candy Machine Could Lead to the Creation of Artificial Organs Previous studies showed that without a network of blood vessels tissues must be smaller than 200 microns (0.007 inches) for cells to be sustained. In the new study, a human, baby-sized ear (1.5 inches), was implanted under the skin of mice.  After two months of implantation, it was thriving and blood vessels and cartilage tissues had formed. The New York Times reported that other scientists have engineered human-size ears in mice before, but noted that those did not form blood vessels and cartilage like the current study, or they were not 3D printed. The scientists zeroed in on the optimal combination for their water-based “ink,” which is a mix of cells and gel.  Through the ITOP system, the hydrogel is combined with a biodegradable plastic to help maintain the tissues shape while it’s transplanted, and a network of micro-channels flow through the structures to let oxygen and nutrients flow into the body as the structures develop a system of blood vessels. Atala told CNN that with this concept, if a patient as a defect or an injury, they can perform an X-ray of that area and download the information digitally into the software program that drives the print heads, which will then “tailor-make” a structure that will fit the patient using the patient’s own cells. In addition to the ear, the team showed muscle tissue, implanted in rats, was strong enough to became vascularized and induce nerve formation after two weeks.  They also printed jaw bone fragments using human stem cells that were the size of a human. The bioprinted bone was implanted in rats and was vascularized five months after implantation. The study received funding from the Armed Forces Institute of Regenerative Medicine. The team hopes that in the future similar results will happen in humans, but for now ongoing studies will measure the long-term success of this effort.


Eita M.,KTH Royal Institute of Technology | Wagberg L.,KTH Royal Institute of Technology | Wagberg L.,Wallenberg Wood Science Center | Muhammed M.,KTH Royal Institute of Technology
Journal of Physical Chemistry C | Year: 2012

The incorporation of nanoparticles into polyelectrolytes thin films opens the way to a broad range of applications depending on the functionality of the nanoparticles. In this work, thin films of ZnO nanoparticles and poly(acrylic acid) (PAA) were built up using the layer-by-layer technique. The thickness of a 20-bilayer film is about 120 nm with a surface roughness of 22.9 nm as measured by atomic force microscopy (AFM). Thin ZnO/PAA films block UV radiation starting at a wavelength of 361 nm due to absorption by ZnO although the films are highly transparent. Due to their high porosity, these thin films show a broadband antireflection in the visible region, and thus they provide selective opacity in the UV region and enhanced transmittance in the visible region up to the near-infrared region. They are also superhydrophilic due to their high porosity and surface roughness. © 2012 American Chemical Society.


Karabulut E.,KTH Royal Institute of Technology | Pettersson T.,KTH Royal Institute of Technology | Ankerfors M.,Innventia Ab | Wagberg L.,KTH Royal Institute of Technology | Wagberg L.,Wallenberg Wood Science Center
ACS Nano | Year: 2012

The preparation of multifunctional films and coatings from sustainable, low-cost raw materials has attracted considerable interest during the past decade. In this respect, cellulose-based products possess great promise due not only to the availability of large amounts of cellulose in nature but also to the new classes of nanosized and well-characterized building blocks of cellulose being prepared from trees or annual plants. However, to fully utilize the inherent properties of these nanomaterials, facile and also sustainable preparation routes are needed. In this work, bioinspired hybrid conjugates of carboxymethylated cellulose nanofibrils (CNFC) and dopamine (DOPA) have been prepared and layer-by-layer (LbL) films of these modified nanofibrils have been built up in combination with a branched polyelectrolyte, polyethyleneimine (PEI), to obtain robust, adhesive, and wet-stable nanocoatings on solid surfaces. It is shown that the chemical functionalization of CNFCs with DOPA molecules alters their conventional properties both in liquid dispersion and at the interface and also influences the LbL film formation by reducing the electrostatic interaction. Although the CNFC-DOPA conjugates show a lower colloidal stability in aqueous dispersions due to charge suppression, it was possible to prepare the LbL films through the consecutive deposition of the building blocks. Adhesive forces between multilayer films prepared using chemically functionalized CNFCs and a silica probe are much stronger in the presence of Fe 3+ than those between a multilayer film prepared from unmodified nanofibrils and a silica probe. The present work demonstrates a facile way to prepare chemically functionalized cellulose nanofibrils whereby more extended applications can produce novel cellulose-based materials with different functionalities. © 2012 American Chemical Society.


News Article | April 1, 2016
Site: www.nanotech-now.com

Home > Press > Transparent wood could one day help brighten homes and buildings Abstract: When it comes to indoor lighting, nothing beats the sun's rays streaming in through windows. Soon, that natural light could be shining through walls, too. Scientists have developed transparent wood that could be used in building materials and could help home and building owners save money on their artificial lighting costs. Their material, reported in ACS' journal Biomacromolecules, also could find application in solar cell windows. Homeowners often search for ways to brighten up their living space. They opt for light-colored paints, mirrors and lots of lamps and ceiling lights. But if the walls themselves were transparent, this would reduce the need for artificial lighting — and the associated energy costs. Recent work on making transparent paper from wood has led to the potential for making similar but stronger materials. Lars Berglund and colleagues wanted to pursue this possibility. The researchers removed lignin from samples of commercial balsa wood. Lignin is a structural polymer in plants that blocks 80 to 95 percent of light from passing through. But the resulting material was still not transparent due to light scattering within it. To allow light to pass through the wood more directly, the researchers incorporated acrylic, often known as Plexiglass. The researchers could see through the resulting material, which was twice as strong as Plexiglass. Although the wood isn't as crystal clear as glass, its haziness provides a possible advantage for solar cells. Specifically, because the material still traps some light, it could be used to boost the efficiency of these cells, the scientists note. The authors acknowledge funding from the Knut and Alice Wallenberg Foundation. About American Chemical Society The American Chemical Society is a nonprofit organization chartered by the U.S. Congress. With nearly 157,000 members, ACS is the world's largest scientific society and a global leader in providing access to chemistry-related research through its multiple databases, peer-reviewed journals and scientific conferences. Its main offices are in Washington, D.C., and Columbus, Ohio. For more information, please click Contacts: Michael Bernstein 202-872-6042 Katie Cottingham, Ph.D. 301-775-8455 Lars Berglund, Ph.D. Wallenberg Wood Science Center Department of Fiber and Polymer Technology KTH Royal Institute of Technology Stockholm, Sweden If you have a comment, please us. Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.


Scientists can 3-D bioprint the shape of an ear using human cells that build up cartilage. Credit: American Chemical Society Athletes, the elderly and others who suffer from injuries and arthritis can lose cartilage and experience a lot of pain. Researchers are now reporting, however, that they have found a way to produce cartilage tissue by 3-D bioprinting an ink containing human cells, and they have successfully tested it in an in vivo mouse model. The development could one day lead to precisely printed implants to heal damaged noses, ears and knees. The researchers presented their work today at the 251st National Meeting & Exposition of the American Chemical Society (ACS). "Three-dimensional bioprinting is a disruptive technology and is expected to revolutionize tissue engineering and regenerative medicine," says Paul Gatenholm, Ph.D. "Our team's interest is in working with plastic surgeons to create cartilage to repair damage from injuries or cancer. We work with the ear and the nose, which are parts of the body that surgeons today have a hard time repairing. But hopefully, they'll one day be able to fix them with a 3-D printer and a bioink made out of a patient's own cells." Gatenholm's team at the Wallenberg Wood Science Center in Sweden is tackling this challenge step by step. First, they had to develop an ink with living human cells that would keep its shape after printing. Previously, printed materials would collapse into an amorphous pile. To create a new bioink, Gatenholm's team mixed polysaccharides from brown algae and tiny cellulose fibrils from wood or made by bacteria, as well as human chondrocytes, which are cells that build up cartilage. Using this mixture, the researchers were able to print living cells in a specific architecture, such as an ear shape, that maintained its form even after printing. The printed cells also produced cartilage in a laboratory dish. "But under in vitro conditions, we have to change the nutrient-filled liquid that the material sits in every other day and add growth factors," Gatenholm says. "It's a very artificial environment." So the next step was to move the research from a lab dish to a living system. Gatenholm's team printed tissue samples and implanted them in mice. The cells survived and produced cartilage. Then, to boost the number of cells, which is another hurdle in tissue engineering, the researchers mixed the chondrocytes with human mesenchymal stem cells from bone marrow. Previous research has indicated that stem cells spur primary cells to proliferate more than they would alone. Preliminary data from in vivo testing over 60 days show the combination does indeed encourage chondrocyte and cartilage production. Gatenholm says further preclinical work needs to be done before moving on to human trials. To ensure the most direct route, he is working with a plastic surgeon to anticipate and address practical and regulatory issues. In addition to cartilage printing, Gatenholm's team is working with a cosmetic company to develop 3-D bioprinted human skin. Cosmetic companies are now prohibited in Europe from testing cosmetics on animals, so they hope to use printed skin to try out makeup, anti-wrinkling techniques and strategies to prevent sun damage. Explore further: Cellulose from wood can be printed in 3-D More information: 3D Bioprinting of Living Tissues and Organs with Polysaccharide Based Bioinks and Human Cells, the 251st National Meeting & Exposition of the American Chemical Society (ACS), 2016.


Lars Berglund, a professor at Wallenberg Wood Science Center at KTH, says that while optically transparent wood has been developed for microscopic samples in the study of wood anatomy, the KTH project introduces a way to use the material on a large scale. The finding was published in the American Chemical Society journal, Biomacromolecules. "Transparent wood is a good material for solar cells, since it's a low-cost, readily available and renewable resource," Berglund says. "This becomes particularly important in covering large surfaces with solar cells." Berglund says transparent wood panels can also be used for windows, and semitransparent facades, when the idea is to let light in but maintain privacy. The optically transparent wood is a type of wood veneer in which the lignin, a component of the cell walls, is removed chemically. "When the lignin is removed, the wood becomes beautifully white. But because wood isn't not naturally transparent, we achieve that effect with some nanoscale tailoring," he says. The white porous veneer substrate is impregnated with a transparent polymer and the optical properties of the two are then matched, he says. "No one has previously considered the possibility of creating larger transparent structures for use as solar cells and in buildings," he says Among the work to be done next is enhancing the transparency of the material and scaling up the manufacturing process, Berglund says. "We also intend to work further with different types of wood," he adds. "Wood is by far the most used bio-based material in buildings. It's attractive that the material comes from renewable sources. It also offers excellent mechanical properties, including strength, toughness, low density and low thermal conductivity." Explore further: Future solar cells may be made of wood More information: Yuanyuan Li et al. Optically Transparent Wood from a Nanoporous Cellulosic Template: Combining Functional and Structural Performance, Biomacromolecules (2016). DOI: 10.1021/acs.biomac.6b00145


News Article | October 26, 2015
Site: phys.org

Thanks to their unique properties, ionic liquids are all in the rage as solvents as, for instance, "green" sustainable chemical processes. Recently, two research teams at Umeå University discovered how enzymes can perform their catalytical processes in a switchable ionic liquid. The discovery paves way for enzymatic refinement of cellulose to precious molecules and industrial products. The results have been published in the journal ChemSusChem. Ionic liquids are salts in fluid form at room temperature – compared with regular cooking salt, sodium chloride, which melts at 800 degrees Celsius. This characteristic means that ionic liquids have unique properties making them important solvents for "green" and sustainable chemistry. In a previous study, the professor in chemistry Jyri-Pekka Mikkolas' research group has discovered that hemicellulose, cellulose and lignin can be selectively separated and dissolved using a new type of so-called switchable ionic liquid. Recently, a team of Magnus Wolf-Watz and Jyri-Pekka Mikkolas research teams have discovered that enzymes can function in this particular ionic liquid. This is far from evident since enzymes have evolved into functioning in water solutions. "Our discovery is a scientific breakthrough! This is the launch that enables us to extract small key molecules directly from wood. There are many applications not in the least in the production of ethanol as fuel but also a number of other things," says Magnus Wolf-Watz, associate professor at the Department of Chemistry. The main experimental technology used is NMR, nuclear magnetic resonance spectroscopy. A crucial component in the work has been the development of a completely new method to determine the enzymatic activity. The assay procedure is based on real time measurements of the chemical reaction using 31P NMR spectroscopy. The NMR infrastructure at Umeå University is at international top class and are funded by the Kempe and Wallenberg Foundations. "This development will be of major importance to the measurement of enzymatic catalysis in complex solutions and preparations, and the method is already being used in new projects," says Jyri-Pekka Mikkola, professor at the Department of Chemistry. The research team is represented by researchers from both biochemistry and technical chemistry. Jyri-Pekka Mikkolas' research team is a part of Bio4Energy's research environment that aims to take Swedish biorefinery research to whole new levels. Jyri-Pekka Mikkolas' research team also belongs to the network Wallenberg Wood Science Center. Explore further: Ionic Liquid's Makeup Measurably Non-Uniform at the Nanoscale More information: Per Rogne et al. Realtime P NMR Investigation on the Catalytic Behavior of the Enzyme Adenylate kinase in the Matrix of a Switchable Ionic Liquid , ChemSusChem (2015). DOI: 10.1002/cssc.201501104


News Article | March 16, 2016
Site: www.cemag.us

Athletes, the elderly, and others who suffer from injuries and arthritis can lose cartilage and experience a lot of pain. Researchers are now reporting, however, that they have found a way to produce cartilage tissue by 3D bioprinting an ink containing human cells, and they have successfully tested it in an in vivo mouse model. The development could one day lead to precisely printed implants to heal damaged noses, ears, and knees. “Three-dimensional bioprinting is a disruptive technology and is expected to revolutionize tissue engineering and regenerative medicine,” says Paul Gatenholm, Ph.D. “Our team’s interest is in working with plastic surgeons to create cartilage to repair damage from injuries or cancer. We work with the ear and the nose, which are parts of the body that surgeons today have a hard time repairing. But hopefully, they’ll one day be able to fix them with a 3D printer and a bioink made out of a patient’s own cells.” Gatenholm’s team at the Wallenberg Wood Science Center in Sweden is tackling this challenge step by step. First, they had to develop an ink with living human cells that would keep its shape after printing. Previously, printed materials would collapse into an amorphous pile. To create a new bioink, Gatenholm’s team mixed polysaccharides from brown algae and tiny cellulose fibrils from wood or made by bacteria, as well as human chondrocytes, which are cells that build up cartilage. Using this mixture, the researchers were able to print living cells in a specific architecture, such as an ear shape, that maintained its form even after printing. The printed cells also produced cartilage in a laboratory dish. “But under in vitro conditions, we have to change the nutrient-filled liquid that the material sits in every other day and add growth factors,” Gatenholm says. “It’s a very artificial environment.” So the next step was to move the research from a lab dish to a living system. Gatenholm’s team printed tissue samples and implanted them in mice. The cells survived and produced cartilage. Then, to boost the number of cells, which is another hurdle in tissue engineering, the researchers mixed the chondrocytes with human mesenchymal stem cells from bone marrow. Previous research has indicated that stem cells spur primary cells to proliferate more than they would alone. Preliminary data from in vivo testing over 60 days show the combination does indeed encourage chondrocyte and cartilage production. Gatenholm says further preclinical work needs to be done before moving on to human trials. To ensure the most direct route, he is working with a plastic surgeon to anticipate and address practical and regulatory issues. In addition to cartilage printing, Gatenholm’s team is working with a cosmetic company to develop 3D bioprinted human skin. Cosmetic companies are now prohibited in Europe from testing cosmetics on animals, so they hope to use printed skin to try out makeup, anti-wrinkling techniques and strategies to prevent sun damage. He acknowledges funding from the Knut and Alice Wallenberg Foundation, Eurostar/Vinnova, and the Västra Götalands Regionen.

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