Tag Archives: nanocellulose

Cellulose biosensor heralds new bioimaging approach to tissue engineering

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I keep an eye on how nanocellulose is being used in various applications and I’m not sure that this cellulose biosensor quite fits the bill as nanocellulose, nonetheless, it’s interesting and that’s enough for me. From a December 12, 2018 Sechenov University (Russia) press release on EurekAlert,

I.M. Sechenov First Moscow State Medical University teamed up together with Irish colleagues to develop a new imaging approach for tissue engineering. The team produced so-called ‘hybrid biosensor’ scaffold materials, which are based on cellulose matrices labeled with pH- and calcium-sensitive fluorescent proteins. These materials enable visualization of the metabolism and other important biomarkers in the engineered artificial tissues by microscopy. The results of the work were published in the Acta Biomaterialia journal.
The success of tissue engineering is based on the use of scaffold matrices – materials that support the viability and direct the growth of cells, tissues, and organoids. Scaffolds are important for basic and applied biomedical research, tissue engineering and regenerative medicine, and are promising for development of new therapeutics. However, the ability ‘to see’ what happens within the scaffolds during the tissue growth poses a significant research challenge

“We developed a new approach allowing visualization of scaffold-grown tissue and cells by using labeling with biosensor fluorescent proteins. Due to the high specificity of labeling and the use of fluorescence microscopy FLIM, we can quantify changes in pH and calcium in the vicinity of cells,” says Dr. Ruslan Dmitriev, Group Leader at the University College Cork and the Institute for Regenerative Medicine (I.M. Sechenov First Moscow State Medical University).
To achieve the specific labeling of cellulose matrices, researchers used well-known cellulose-binding proteins. The use of extracellular pH- and calcium-sensitive biosensors allow for analysis of cell metabolism: indeed, the extracellular acidification is directly associated with the balance of cell energy production pathways and the glycolytic flux (release of lactate). It is also a frequent hallmark of cancer and transformed cell types. On the other hand, calcium plays a key role in the extra- and intracellular signaling affecting cell growth and differentiation.

The approach was tested on different types of cellulose matrices (bacterial and produced from decellularised plant tissues) using 3D culture of human colon cancer cells and stem-cell derived mouse small intestinal organoids. The scaffolds informed on changes in the extracellular acidification and were used together with the analysis of real-time oxygenation of intestinal organoids. The resulting data can be presented in the form of colour maps, corresponding to the areas of cell growth within different microenvironments.

“Our results open new prospects in the imaging of tissue-engineered constructs for regenerative medicine. They enable deeper understanding of tissue metabolism in 3D and are also highly promising for commercialisation,” concludes Dr. Dmitriev.

The researchers have provided an image to illustrate their work,

Caption: A 3D reconstruction of a cellulose matrix stained with a pH-sensitive biosensor. Credit: Dr. R. Dmitriev

Here’s a link to and a citation for the paper,

Cellulose-based scaffolds for fluorescence lifetime imaging-assisted tissue engineering by Neil O’Donnell, Irina A. Okkelman, Peter Timashev, Tatyana I.Gromovykh, Dmitri B. Papkovsky, Ruslan I.Dmitriev. Acta Biomaterialia Volume 80, 15 October 2018, Pages 85-96 DOI: https://doi.org/10.1016/j.actbio.2018.09.034


This paper is behind a paywall.

Two new Canada Excellence Research Chairs (CERC) at the University of British Columbia (Canada) bring bioproducts and precision medicine skills

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This is very fresh news. One of these chairs has not yet been listed (at the time of this writing) as a member of the institute that he will be leading. Here’s the big picture news from an
April 17, 2019 University of British Columbia (UBC) news release, Note: Links have been removed,

Two internationally recognized researchers join the University of British Columbia as Canada Excellence Research Chairs, bringing international talent in the fields of forest bioproducts and precision cancer drug design.

Orlando Rojas has accepted the Canada Excellence Research Chair in Forest Bioproducts, while Sriram Subramaniam will hold the Gobind Khorana Canada Excellence Research Chair in Precision Cancer Drug Design—named after late Nobel Prize-winning UBC biochemistry professor Har Gobind Khorana.

“We are delighted to welcome Dr. Rojas and Dr. Subramaniam to UBC,” said UBC President and Vice-Chancellor, Professor Santa J. Ono. “Thanks to the CERC program and the generous support of our partners, including VGH & UBC Hospital Foundation, we have an opportunity to continue to build on UBC’s reputation as a global leader in these vitally important research fields.”

The Canada Excellence Research Chairs (CERC) program was established by the federal government in 2008 to attract top research talent from abroad to Canada. UBC will receive up to $10 million over seven years to support each chair and their research teams. In addition, a philanthropic gift of $18 million made to VGH & UBC Hospital Foundation will support cancer drug design that will be carried out by Subramaniam in close partnership with UBC and the Vancouver Prostate Centre at VGH.

“VGH & UBC Hospital Foundation is honoured to announce an $18 million gift from Aqueduct Foundation on behalf of an anonymous donor that will increase capacity for discovering and testing new life-saving cancer treatments right here in B.C. This funding will specifically support the design of precise, targeted and cost-effective drugs for cancer in work led by Dr. Sriram Subramaniam in close partnership with UBC and the Vancouver Prostate Centre at VGH and other research centres,” says Barbara Grantham, president and CEO of VGH & UBC Hospital Foundation.

Bioproducts

The April 17, 2019 UBC news release, goes on to describe the two new chairs,

Breaking new ground in forest bioproducts

Orlando Rojas comes to UBC from Aalto University [Finland], where he directs with VTT, the Technical Research Centre of Finland, a scientific cluster to advance the Finnish materials bio-economy. A recipient of the Anselme Payen Award—one of the highest international recognitions in the area of cellulose and renewable materials—and an elected member of the American Chemical Society and the Finnish Academy of Science and Letters, Rojas is recognized as a worldwide leader in the area of nanocelluloses.

“I’m thrilled to join an already stellar team of researchers at UBC’s BioProducts Institute,” said Rojas. “My research is aimed at uncovering solutions that can be found in nature to fulfill our material needs by using sustainably, readily available bio-resources. I hope to break new grounds to create positive societal impacts and to better our quality of life.”

As the CERC in Forest Bioproducts, Rojas will establish a world-class research program in genomics, synthetic biology, materials science and engineering. Together with his team and by applying cutting-edge nano- and biotechnologies, he will discover new strategies to isolate and transform biomass components—non-fossil organic materials derived from plants (including wood)—as well as side-streams and residuals from forestry and agriculture, oils and biomolecules. The work will lead to the generation of new bio-based precursors and advanced materials critical to the future bioeconomy. Rojas will be the scientific director of the UBC BioProducts Institute, synergizing a distinguished group of professors and researchers across campus who will conduct multi- and cross-disciplinary research that will position UBC at the forefront in the area.

As climate change continues to be the greatest threat to our world, the need to transition toward a more sustainable bio-based circular economy is critical. Rojas’ research is vital in understanding the role of forest and other plant-based resources in facilitating the transition to renewable materials and bioproducts.

As I noted earlier, Rojas has yet to be added to the UBC BioProducts Institute roster but I did find a listing of his published papers on Google Scholar and noted a number of them are focused on nanocellulose with at least one study on cellulose nanocrystals (CNC),

  • Cellulose nanocrystals: chemistry, self-assembly, and applications [by] Y Habibi, LA Lucia, OJ Rojas Chemical reviews 110 (6), 3479-3500

The University of British Columbia was the site for much of the early work in Canada and internationally on cellulose nanocrystals. After the provincial government lost interest in supporting it, the researchers at FPInnovations (I think it was a university spin-off organization) moved their main headquarters (leaving a smaller group in British Columbia) to the province of Québec where they receive significant support . In turn, FPInnovations spun-off a company, CelluForce which produces CNC from forest products.This news about Roja’s appointment would seem to make for an interesting development in Canada’s nanocellulose story.

Precision medicine with cryo-electron microscopy

Now for the second CERC appointment, from the April 17, 2019 UBC news release,

Putting Canada at the forefront of precision medicine

Sriram Subramaniam is recognized as a global leader in the emerging field of cryo-electron microscopy, or cryo-EM, a technology that has sparked a revolution in imaging of protein complexes. Subramaniam and his team demonstrated that proteins and protein-bound drugs could be visualized at atomic resolution with cryo-EM, paving the way for this technology to be used in accelerating drug discovery.

Subramaniam comes to UBC’s faculty of medicine from the US National Cancer Institute (NCI) at the National Institutes of Health (NIH) where he led a research team that made seminal advances in molecular and cellular imaging using electron microscopy, including work on advancing vaccine design for viruses such as HIV. Subramaniam is also founding director of the National Cryo-EM Program at NCI, NIH.

As the Gobind Khorana Canada Excellence Research Chair in Precision Cancer Drug Design, Subramaniam will establish and direct a laboratory located at UBC, aimed at bringing about transformative discoveries in cancer, neuroscience and infectious disease. Subramaniam is appointed both in the department of urologic sciences and in biochemistry and molecular biology at UBC, and is linked to the precision cancer drug design program at the Vancouver Prostate Centre at VGH.

His research is supported by a philanthropic gift of $18 million made to VGH & UBC Hospital Foundation. He will work in close partnership with the Vancouver Prostate Centre at VGH.

“We would not be able to undertake this path aimed at leveraging advances in imaging technology to improve patient outcomes if it weren’t for the generous support of the donor, the Canadian government, and VGH & UBC Hospital Foundation,” said Subramaniam. “I am proud to be part of a team of outstanding researchers here in Vancouver, and working together to harness the true potential of cryo-EM to accelerate drug design. Our work has the potential to establish VGH, UBC and Canada at the forefront of the emerging era of precision medicine.”

I was not able to find much in the way of additional information about Subramaniam—other than this (from the High Resolution Electron Microscopy Lab Members webpage),

Sriram Subramaniam received his Ph.D. in Physical Chemistry from Stanford University and completed postdoctoral training in the Departments of Chemistry and Biology at M.I.T. [Massachusetts Institute of Technology] He is chief of the Biophysics Section in the Laboratory of Cell Biology at the Center for Cancer Research, National Cancer Institute. He holds a visiting faculty appointment at the Johns Hopkins University School of Medicine.

Welcome to both Orlando J. Rohas and Sriram Subramaniam!

Wooden supercapacitors: a cellulose nanofibril story

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A May 24, 2018 news item on Nanowerk announces a technique for making sustainable electrodes (Note: A link has been removed),

Carbon aerogels are ultralight, conductive materials, which are extensively investigated for applications in supercapacitor electrodes in electrical cars and cell phones. Chinese scientists have now found a way to make these electrodes sustainably. The aerogels can be obtained directly from cellulose nanofibrils, the abundant cell-wall material in wood, finds the study reported in the journal Angewandte Chemie (“Wood-Derived Ultrathin Carbon Nanofiber Aerogels”).

A May 24, 2018 Wiley Publications press release, which originated the news item, explains further,

Supercapacitors are capacitors that can take up and release a very large amount of energy in a very short time. Key requirements for supercapacitor electrodes are a large surface area and conductivity, combined with a simple production method. Another growing issue in supercapacitor production–mainly for smartphone and electric car technologies–is sustainability. However, sustainable and economical production of carbon aerogels as supercapacitor electrode materials is possible, propose Shu-Hong Yu and colleagues from the University of Science and Technology of China, Hefei, China.

Carbon aerogels are ultralight conductive materials with a very large surface area. They can be prepared by two production routes: the first and cheapest starts from mostly phenolic components and produces aerogels with improvable conductivity, while the second route is based on graphene- and carbon-nanotube precursors. The latter method delivers high-performance aerogels but is expensive and non-environmentally friendly. In their search for different precursors, Yu and colleagues have found an abundant, far less expensive, and sustainable source: wood pulp.

Well, not really wood pulp, but its major ingredient, nanocellulose. Plant cell walls are stabilized by fibrous nanocellulose, and this extractable material has very recently stimulated substantial research and technological development. It forms a highly porous, but very stable transparent network, and, with the help of a recent technique–oxidation with a radical scavenger called TEMPO–it forms a microporous hydrogel of highly oriented cellulose nanofibrils with a uniform width and length. As organic aerogels are produced from hydrogels by drying and pyrolysis, the authors attempted pyrolysis of supercritically or freeze-dried nanofibrillated cellulose hydrogel.

As it turns out, the method was not as straightforward as expected because ice crystal formation and insufficient dehydration hampered carbonization, according to the authors. Here, a trick helped. The scientists pyrolyzed the dried gel in the presence of the organic acid catalyst para-toluenesulfonic acid. The catalyst lowered the decomposition temperature and yielded a “mechanically stable and porous three-dimensional nanofibrous network” featuring a “large specific surface area and high electrical conductivity,” the authors reported.

The authors also demonstrated that their wood-derived carbon aerogel worked well as a binder-free electrode for supercapacitor applications. The material displayed electrochemical properties comparable to commercial electrodes. The method is an interesting and innovative way in which to fabricate sustainable materials suitable for use in high-performance electronic devices.

This is the first time I’ve seen work on wood-based nanocellulose from China. Cellulose according to its Wikipedia entry is: ” … the most abundant organic polymer on Earth.” For example, there’s more cellulose in cotton than there is wood. So, I find it interesting that in a country not known for its forests, nanocellulose (in this project anyway) is being derived from wood.

Here’s a link to and a citation for the paper,

Wood‐Derived Ultrathin Carbon Nanofiber Aerogels by Si‐Cheng Li, Bi‐Cheng Hu, Dr. Yan‐Wei Ding, Prof. Hai‐Wei Liang, Chao Li, Dr. Zi‐You Yu, Dr. Zhen‐Yu Wu, Prof. Wen‐Shuai Chen, Prof. Shu‐Hong Yu. Angewandt Chemie First published: 23 April 2018 DOI: https://doi.org/10.1002/anie.201802753

This paper is behind a paywall.

Canadian research into nanomaterial workplace exposure in the air and on surfaces

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An August 30, 2018 news item on Nanowerk announces the report,

The monitoring of air contamination by engineered nanomaterials (ENM) is a complex process with many uncertainties and limitations owing to the presence of particles of nanometric size that are not ENMs, the lack of validated instruments for breathing zone measurements and the many indicators to be considered.

In addition, some organizations, France’s Institut national de recherche et de sécurité (INRS) and Québec’s Institut de recherche Robert-Sauvé en santé et en sécurité du travail (IRSST) among them, stress the need to also sample surfaces for ENM deposits.

In other words, to get a better picture of the risks of worker exposure, we need to fine-tune the existing methods of sampling and characterizing ENMs and develop new one. Accordingly, the main goal of this project was to develop innovative methodological approaches for detailed qualitative as well as quantitative characterization of workplace exposure to ENMs.

A PDF of the 88-page report is available in English or in French.

An August 30, 2018 (?) abstract of the IRSST report titled An Assessment of Methods of Sampling and Characterizing Engineered Nanomaterials in the Air and on Surfaces in the Workplace (2nd edition) by Maximilien Debia, Gilles L’Espérance, Cyril Catto, Philippe Plamondon, André Dufresne, Claude Ostiguy, which originated the news item, outlines what you can expect from the report,

This research project has two complementary parts: a laboratory investigation and a fieldwork component. The laboratory investigation involved generating titanium dioxide (TiO2) nanoparticles under controlled laboratory conditions and studying different sampling and analysis devices. The fieldwork comprised a series of nine interventions adapted to different workplaces and designed to test a variety of sampling devices and analytical procedures and to measure ENM exposure levels among Québec workers.

The methods for characterizing aerosols and surface deposits that were investigated include: i) measurement by direct-reading instruments (DRI), such as condensation particle counters (CPC), optical particle counters (OPC), laser photometers, aerodynamic diameter spectrometers and electric mobility spectrometer; ii) transmission electron microscopy (TEM) or scanning transmission electron microscopy (STEM) with a variety of sampling devices, including the Mini Particle Sampler® (MPS); iii) measurement of elemental carbon (EC); iv) inductively coupled plasma mass spectrometry (ICP-MS) and (v) Raman spectroscopy.

The workplace investigations covered a variety of industries (e.g., electronics, manufacturing, printing, construction, energy, research and development) and included producers as well as users or integrators of ENMs. In the workplaces investigated, we found nanometals or metal oxides (TiO2, SiO2, zinc oxides, lithium iron phosphate, titanate, copper oxides), nanoclays, nanocellulose and carbonaceous materials, including carbon nanofibers (CNF) and carbon nanotubes (CNT)—single-walled (SWCNT) as well as multiwalled (MWCNT).

The project helped to advance our knowledge of workplace assessments of ENMs by documenting specific tasks and industrial processes (e.g., printing and varnishing) as well as certain as yet little investigated ENMs (nanocellulose, for example).

Based on our investigations, we propose a strategy for more accurate assessment of ENM exposure using methods that require a minimum of preanalytical handling. The recommended strategy is a systematic two-step assessment of workplaces that produce and use ENMs. The first step involves testing with different DRIs (such as a CPC and a laser photometer) as well as sample collection and subsequent microscopic analysis (MPS + TEM/STEM) to clearly identify the work tasks that generate ENMs. The second step, once work exposure is confirmed, is specific quantification of the ENMs detected. The following findings are particularly helpful for detailed characterization of ENM exposure:

  1. The first conclusive tests of a technique using ICP-MS to quantify the metal oxide content of samples collected in the workplace
  2. The possibility of combining different sampling methods recommended by the National Institute for Occupational Safety and Health (NIOSH) to measure elemental carbon as an indicator of NTC/NFC, as well as demonstration of the limitation of this method stemming from observed interference with the black carbon particles required to synthesis carbon materials (for example, Raman spectroscopy showed that less than 6% of the particles deposited on the electron microscopy grid at one site were SWCNTs)
  3. The clear advantages of using an MPS (instead of the standard 37-mm cassettes used as sampling media for electron microscopy), which allows quantification of materials
  4. The major impact of sampling time: a long sampling time overloads electron microscopy grids and can lead to overestimation of average particle agglomerate size and underestimation of particle concentrations
  5. The feasibility and utility of surface sampling, either with sampling pumps or passively by diffusion onto the electron microscopy grids, to assess ENM dispersion in the workplace

These original findings suggest promising avenues for assessing ENM exposure, while also showing their limitations. Improvements to our sampling and analysis methods give us a better understanding of ENM exposure and help in adapting and implementing control measures that can minimize occupational exposure.

You can download the full report in either or both English and French from the ‘Nanomaterials – A Guide to Good Practices Facilitating Risk Management in the Workplace, 2nd Edition‘ webpage.

Stronger than steel and spider silk: artificial, biodegradable, cellulose nanofibres

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This is an artificial and biodegradable are two adjectives you don’t usually see united by the conjunction, and. However, it is worth noting that the artificial material is initially derived from a natural material, cellulose. Here’s more from a May 16, 2018 news item on ScienceDaily,

At DESY’s [Deutsches Elektronen-Synchrotron] X-ray light source PETRA III, a team led by Swedish researchers has produced the strongest bio-material that has ever been made. The artifical, but bio-degradable cellulose fibres are stronger than steel and even than dragline spider silk, which is usually considered the strongest bio-based material. The team headed by Daniel Söderberg from the KTH Royal Institute of Technology in Stockholm reports the work in the journal ACS Nano of the American Chemical Society.

A May 16, 2018 DESY press release (also on EurekAlert), which originated the news item, provides more detail,

The ultrastrong material is made of cellulose nanofibres (CNF), the essential building blocks of wood and other plant life. Using a novel production method, the researchers have successfully transferred the unique mechanical properties of these nanofibres to a macroscopic, lightweight material that could be used as an eco-friendly alternative for plastic in airplanes, cars, furniture and other products. “Our new material even has potential for biomedicine since cellulose is not rejected by your body”, explains Söderberg.

The scientists started with commercially available cellulose nanofibres that are just 2 to 5 nanometres in diameter and up to 700 nanometres long. A nanometre (nm) is a millionth of a millimetre. The nanofibres were suspended in water and fed into a small channel, just one millimetre wide and milled in steel. Through two pairs of perpendicular inflows additional deionized water and water with a low pH-value entered the channel from the sides, squeezing the stream of nanofibres together and accelerating it.

This process, called hydrodynamic focussing, helped to align the nanofibres in the right direction as well as their self-organisation into a well-packed macroscopic thread. No glue or any other component is needed, the nanofibres assemble into a tight thread held together by supramolecular forces between the nanofibres, for example electrostatic and Van der Waals forces.

With the bright X-rays from PETRA III the scientists could follow and optimise the process. “The X-rays allow us to analyse the detailed structure of the thread as it forms as well as the material structure and hierarchical order in the super strong fibres,” explains co-author Stephan Roth from DESY, head of the Micro- and Nanofocus X-ray Scattering Beamline P03 where the threads were spun. “We made threads up to 15 micrometres thick and several metres in length.”

Measurements showed a tensile stiffness of 86 gigapascals (GPa) for the material and a tensile strength of 1.57 GPa. “The bio-based nanocellulose fibres fabricated here are 8 times stiffer and have strengths higher than natural dragline spider silk fibres,” says Söderberg. “If you are looking for a bio-based material, there is nothing quite like it. And it is also stronger than steel and any other metal or alloy as well as glass fibres and most other synthetic materials.” The artificial cellulose fibres can be woven into a fabric to create materials for various applications. The researchers estimate that the production costs of the new material can compete with those of strong synthetic fabrics. “The new material can in principle be used to create bio-degradable components,” adds Roth.

The study describes a new method that mimics nature’s ability to accumulate cellulose nanofibres into almost perfect macroscale arrangements, like in wood. It opens the way for developing nanofibre material that can be used for larger structures while retaining the nanofibres’ tensile strength and ability to withstand mechanical load. “We can now transform the super performance from the nanoscale to the macroscale,” Söderberg underlines. “This discovery is made possible by understanding and controlling the key fundamental parameters essential for perfect nanostructuring, such as particle size, interactions, alignment, diffusion, network formation and assembly.” The process can also be used to control nanoscale assembly of carbon tubes and other nano-sized fibres.

(There are some terminology and spelling issues, which are described at the end of this post.)

Let’s get back to a material that rivals spider silk and steel for strength (for some reason that reminded me of an old carnival game where you’d test your strength by swinging a mallet down on a ‘teeter-totter-like’ board and sending a metal piece up a post to make a bell ring). From a May 16, 2018 DESY press release (also on EurekAlert), which originated the news item,

The ultrastrong material is made of cellulose nanofibres (CNF), the essential building blocks of wood and other plant life. Using a novel production method, the researchers have successfully transferred the unique mechanical properties of these nanofibres to a macroscopic, lightweight material that could be used as an eco-friendly alternative for plastic in airplanes, cars, furniture and other products. “Our new material even has potential for biomedicine since cellulose is not rejected by your body”, explains Söderberg.

The scientists started with commercially available cellulose nanofibres that are just 2 to 5 nanometres in diameter and up to 700 nanometres long. A nanometre (nm) is a millionth of a millimetre. The nanofibres were suspended in water and fed into a small channel, just one millimetre wide and milled in steel. Through two pairs of perpendicular inflows additional deionized water and water with a low pH-value entered the channel from the sides, squeezing the stream of nanofibres together and accelerating it.

This process, called hydrodynamic focussing, helped to align the nanofibres in the right direction as well as their self-organisation into a well-packed macroscopic thread. No glue or any other component is needed, the nanofibres assemble into a tight thread held together by supramolecular forces between the nanofibres, for example electrostatic and Van der Waals forces.

With the bright X-rays from PETRA III the scientists could follow and optimise the process. “The X-rays allow us to analyse the detailed structure of the thread as it forms as well as the material structure and hierarchical order in the super strong fibres,” explains co-author Stephan Roth from DESY, head of the Micro- and Nanofocus X-ray Scattering Beamline P03 where the threads were spun. “We made threads up to 15 micrometres thick and several metres in length.”

Measurements showed a tensile stiffness of 86 gigapascals (GPa) for the material and a tensile strength of 1.57 GPa. “The bio-based nanocellulose fibres fabricated here are 8 times stiffer and have strengths higher than natural dragline spider silk fibres,” says Söderberg. “If you are looking for a bio-based material, there is nothing quite like it. And it is also stronger than steel and any other metal or alloy as well as glass fibres and most other synthetic materials.” The artificial cellulose fibres can be woven into a fabric to create materials for various applications. The researchers estimate that the production costs of the new material can compete with those of strong synthetic fabrics. “The new material can in principle be used to create bio-degradable components,” adds Roth.

The study describes a new method that mimics nature’s ability to accumulate cellulose nanofibres into almost perfect macroscale arrangements, like in wood. It opens the way for developing nanofibre material that can be used for larger structures while retaining the nanofibres’ tensile strength and ability to withstand mechanical load. “We can now transform the super performance from the nanoscale to the macroscale,” Söderberg underlines. “This discovery is made possible by understanding and controlling the key fundamental parameters essential for perfect nanostructuring, such as particle size, interactions, alignment, diffusion, network formation and assembly.” The process can also be used to control nanoscale assembly of carbon tubes and other nano-sized fibres.

Here’s a link to and a citation for the paper,

Multiscale Control of Nanocellulose Assembly: Transferring Remarkable Nanoscale Fibril Mechanics to Macroscale Fibers by Nitesh Mittal, Farhan Ansari, Krishne Gowda V, Christophe Brouzet, Pan Chen, Per Tomas Larsson, Stephan V. Roth, Fredrik Lundell, Lars Wågberg, Nicholas A. Kotov, and L. Daniel Söderberg. ACS Nano, Article ASAP DOI: 10.1021/acsnano.8b01084 Publication Date (Web): May 9, 2018

Copyright © 2018 American Chemical Society

This paper is open access and accompanied by this image illustrating the work,

Courtesy: American Chemical Society and the researchers [Note: The bottom two images of cellulose nanofibres, which are constittuents of an artificial cellulose fibre, appear to be from a scanning tunneling microsscope. Credit: Nitesh Mittal, KTH Stockholm

This news has excited interest at General Electric (GE) (its Wikipedia entry), which has highlighted the work in a May 25, 2018 posting (The 5 Coolest Things On Earth This Week) by Tomas Kellner on the GE Reports blog.

Terminology and spelling

I’ll start with spelling since that’s the easier of the two. In some parts of the world it’s spelled ‘fibres’ and in other parts of the world it’s spelled ‘fibers’. When I write the text in my post, it tends to reflect the spelling used in the news/press releases. In other words, I swing in whichever direction the wind is blowing.

For diehards only

As i understand the terminology situation, nanocellulose and cellulose nanomaterials are interchangeable generic terms. Further, cellulose nanofibres (CNF) seems to be another generic term and it encompasses both cellulose nanocrystals (CNC) and cellulose nanofibrils (CNF). Yes, there appear to be two CNFs. Making matters more interesting is the fact that cellulose nanocrystals were originally christened nanocrystalline cellulose (NCC). For anyone who follows the science and technology scene, it becomes obvious that competing terminologies are the order of the day. Eventually the dust settles and naming conventions are resolved. More or less.

Ordinarily I would reference the Nanocellulose Wikipedia entry in my attempts to clarify the issues but it seems that the writers for the entry have not caught up to the current naming convention for cellulose nanocrystals, still referring to the material as nanocrystalline cellulose. This means, I can’t trust the rest of the entry, which has only one CNF (cellulose nanofibres).

I have paid more attention to the NCC/CNC situation and am not as familiar with the CNF situation. Using, NCC/CNC as an example of a terminology issue, I believe it was first developed in Canada and it was Canadian researchers who were pushing their NCC terminology while the international community pushed back with CNC.

In the end, NCC became a brand name, which was trademarked by CelluForce, a Canadian company in the CNC market. From the CelluForce Products page on Cellulose Nanocrystals,

…

CNC are not all made equal. The CNC produced by CelluForce is called CelluForce NCCTM and has specific properties and are especially easy to disperse. CelluForce NCCTM is the base material that CelluForce uses in all its products. This base material can be modified and tailored to suit the specific needs in various applications.

These, days CNC is almost universally used but NCC (not as a trademark) is a term still employed on occasion (and, oddly, the researchers are not necessarily Canadian).

Should anyone have better information about terminology issues, please feel free to comment.

Wood’s natural nanotechnology

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“Wood’s natural nanotechnology: is an unusual term and it comes at the end of this February 7, 2018 University of Maryland (US) news release about a technique which will make wood stronger than titanium alloy,

Engineers at the University of Maryland in College Park have found a way to make wood more than ten times times stronger and tougher than before, creating a natural substance that is stronger than titanium alloy.

“This new way to treat wood makes it twelve times stronger than natural wood and ten times tougher,” said Liangbing Hu, the leader of the team that did the research, to be published on Thursday [February 7, 2018] in the journal Nature. “This could be a competitor to steel or even titanium alloys, it is so strong and durable. It’s also comparable to carbon fiber, but much less expensive.” Hu is an associate professor of materials science and engineering and a member of the Maryland Energy Innovation Institute.

“It is both strong and tough, which is a combination not usually found in nature,” said Teng Li, the co-leader of the team and the Samuel P. Langley associate professor of mechanical engineering at the University of Maryland. His team measured the dense wood’s mechanical properties.  “It is as strong as steel, but six times lighter. It takes 10 times more energy to fracture than natural wood. It can even be bent and molded at the beginning of the process.”

The team’s process begins by removing the wood’s lignin, the part of the wood that makes it both rigid and brown in color. Then it is compressed under mild heat, at about 150 F. This causes the cellulose fibers to become very tightly packed. Any defects like holes or knots are crushed together.  The treatment process was extended a little further with a coat of paint.

The scientists found that the wood’s fibers are pressed together so tightly that they can form strong hydrogen bonds, like a crowd of people who can’t budge – who are also holding hands. The compression makes the wood five times thinner than its original size.

The team also tested the material by shooting a bullet-like projectile at it. Unlike natural wood, which was blown straight through, the fully treated wood actually stopped the projectile partway through.

“Soft woods like pine or balsa, which grow fast and are more environmentally friendly, could replace slower-growing but denser woods like teak, in furniture or buildings,” Hu said.

“The paper provides a highly promising route to the design of light weight high performance structural materials, with tremendous potential for a broad range of applications where high strength, large toughness and superior ballistic resistance are desired, “ said Dr. Huajian Gao, a professor at Brown University, who was not involved in the study. “It is particularly exciting to note that the method is versatile for various species of wood and fairly easy to implement.”

“This kind of wood could be used in cars, airplanes, buildings – any application where steel is used,” Hu said.

“The two-step process reported in this paper achieves exceptionally high strength, much beyond what [is] reported in the literature,” said Dr. Zhigang Suo, a professor of mechanics and materials at Harvard University, also not involved with the study. “Given the abundance of wood, as well as other cellulose-rich plants, this paper inspires imagination.”

“The most outstanding observation, in my view, is the existence of a limiting concentration of lignin, the glue between wood cells, to maximize the mechanical performance of the densified wood. Too little or too much removal lower the strength compared to a maximum value achieved at intermediate or partial lignin removal. This reveals the subtle balance between hydrogen bonding and the adhesion imparted by such polyphenolic compound. Moreover, of outstanding interest, is the fact that that wood densification leads to both, increased strength and toughness, two properties that usually offset each other,” said Orlando J. Rojas, a professor at Aalto University in Finland.

Hu’s research has explored the capacities of wood’s natural nanotechnology [emphasis mine]. They previously made a range of emerging technologies out of nanocellulose related materials: (1) super clear paper for replacing plastic; (2) photonic paper for improving solar cell efficiency by 30%; (3) a battery and a supercapacitor out of wood; (4) a battery from a leaf; (5) transparent wood for energy efficient buildings; (6) solar water desalination for drinking and specifically filtering out toxic dyes. These wood-based emerging technologies are being commercialized through a UMD spinoff company, Inventwood LLC.

At a guess, “wood’s natural nanotechnology” refers to the properties of wood and other forms of cellulose at the nanoscale.

Here’s a link to and a citation for the paper,

Processing bulk natural wood into a high-performance structural material by Jianwei Song, Chaoji Chen, Shuze Zhu, Mingwei Zhu, Jiaqi Dai, Upamanyu Ray, Yiju Li, Yudi Kuang, Yongfeng Li, Nelson Quispe, Yonggang Yao, Amy Gong, Ulrich H. Leiste, Hugh A. Bruck, J. Y. Zhu, Azhar Vellore, Heng Li, Marilyn L. Minus, Zheng Jia, Ashlie Martini, Teng Li, & Liangbing Hu. Nature volume 554, pages 224–228 (08 February 2018) doi:10.1038/nature25476 Published online: 07 February 2018

This paper is behind a paywall.

h/t Feb. 7, 2018 news item on Nanowerk and, finally, you can find out more about the wood-based emerging technologies being commcercialized by the University of Maryland here on the Inventwood website.

Cellulose- and chitin-based biomaterial to replace plastics?

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Although the term is not actually used in the news release, one of the materials used to create a new biomaterial could safely be described as nanocellulose. From a Sept. 20, 2017 Pennsylvania State University (Penn State) news release (also on EurekAlert) by Jeff Mulhollem,

An inexpensive biomaterial that can be used to sustainably replace plastic barrier coatings in packaging and many other applications has been developed by Penn State researchers, who predict its adoption would greatly reduce pollution.

Completely compostable, the material — a polysaccharide polyelectrolyte complex — is comprised of nearly equal parts of treated cellulose pulp from wood or cotton, and chitosan, which is derived from chitin — the primary ingredient in the exoskeletons of arthropods and crustaceans. The main source of chitin is the mountains of leftover shells from lobsters, crabs and shrimp consumed by humans.

These environmentally friendly barrier coatings have numerous applications ranging from water-resistant paper, to coatings for ceiling tiles and wallboard, to food coatings to seal in freshness, according to lead researcher Jeffrey Catchmark, professor of agricultural and biological engineering, College of Agricultural Sciences.

“The material’s unexpected strong, insoluble adhesive properties are useful for packaging as well as other applications, such as better performing, fully natural wood-fiber composites for construction and even flooring,” he said. “And the technology has the potential to be incorporated into foods to reduce fat uptake during frying and maintain crispness. Since the coating is essentially fiber-based, it is a means of adding fiber to diets.”

The amazingly sturdy and durable bond between carboxymethyl cellulose and chitosan is the key, he explained. The two very inexpensive polysaccharides — already used in the food industry and in other industrial sectors — have different molecular charges and lock together in a complex that provides the foundation for impervious films, coatings, adhesives and more.

The potential reduction of pollution is immense if these barrier coatings replace millions of tons of petroleum-based plastic associated with food packaging used every year in the United States — and much more globally, Catchmark noted.

He pointed out that the global production of plastic is approaching 300 million tons per year. In a recent year, more than 29 million tons of plastic became municipal solid waste in the U.S. and almost half was plastic packaging. It is anticipated that 10 percent of all plastic produced globally will become ocean debris, representing a significant ecological and human health threat.

crab shells

The material is comprised of cellulose pulp from wood or cotton, and chitosan, derived from chitin, the primary ingredient in the exoskeletons of arthropods and crustaceans. The main source of chitin is shells from lobsters, crabs and shrimp. Image: © iStock Photo OKRAD

The polysaccharide polyelectrolyte complex coatings performed well in research, the findings of which were published recently in Green Chemistry. Paperboard coated with the biomaterial, comprised of nanostructured fibrous particles of carboxymethyl cellulose and chitosan, exhibited strong oil and water barrier properties. The coating also resisted toluene, heptane and salt solutions and exhibited improved wet and dry mechanical and water vapor barrier properties.

“These results show that polysaccharide polyelectrolyte complex-based materials may be competitive barrier alternatives to synthetic polymers for many commercial applications,” said Catchmark, who, in concert with Penn State, has applied for a patent on the coatings.

“In addition, this work demonstrates that new, unexpected properties emerge from multi-polysaccharide systems engaged in electrostatic complexation, enabling new high-performance applications.”

Catchmark began experimenting with biomaterials that might be used instead of plastics a decade or so ago out of concerns for sustainability. He became interested in cellulose, the main component in wood, because it is the largest volume sustainable, renewable material on earth. Catchmark studied its nanostructure — how it is assembled at the nanoscale.

He believed he could develop natural materials that are more robust and improve their properties, so that they could compete with synthetic materials that are not sustainable and generate pollution — such as the low-density polyethylene laminate applied to paper board, Styrofoam and solid plastic used in cups and bottles.

“The challenge is, to do that you’ve got to be able to do it in a way that is manufacturable, and it has to be less expensive than plastic,” Catchmark explained. “Because when you make a change to something that is greener or sustainable, you really have to pay for the switch. So it has to be less expensive in order for companies to actually gain something from it. This creates a problem for sustainable materials — an inertia that has to be overcome with a lower cost.”

lab vials

The amazingly sturdy and durable bond between carboxymethyl cellulose and chitosan is the key. The two very inexpensive polysaccharides, already used in the food industry and in other industrial sectors, have different molecular charges and lock together in a complex that provides the foundation for impervious films, coatings, adhesives and more. Image: Penn State

Funded by a Research Applications for Innovation grant from the College of Agricultural Sciences, Catchmark currently is working to develop commercialization partners in different industry sectors for a wide variety of products.

“We are trying to take the last step now and make a real impact on the world, and get industry people to stop using plastics and instead use these natural materials,” he said. “So they (consumers) have a choice — after the biomaterials are used, they can be recycled, buried in the ground or composted, and they will decompose. Or they can continue to use plastics that will end up in the oceans, where they will persist for thousands of years.”

Also involved in the research were Snehasish Basu, post-doctoral scholar, and Adam Plucinski, master’s degree student, now instructor of engineering at Penn State Altoona. Staff in Penn State’s Material Research Institute provided assistance with the project.

The U.S. Department of Agriculture supported this work. Southern Champion Tray, of Chattanooga, Tennessee, provided paperboard and information on its production for experiments.

Here’s a link to and a citation for the paper,

Sustainable barrier materials based on polysaccharide polyelectrolyte complexes by
Snehasish Basu, Adam Plucinski, and Jeffrey M. Catchmark. Green Chemistry 2017, 19, 4080-4092 DOI: 10.1039/C7GC00991G

This paper is behind a paywall. One comment, I found an anomaly on the page when I visited. At the top of the citation page, it states that this is issue 17 of Green Chemistry but the citation in the column on the right is “2017, 19 … “, which would be issue 19.

Bio-based standup pouches (food packaging) made from cellulose

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CAPTION: VTT has developed lightweight 100% bio-based stand-up pouches with high technical performance. (Photo by VTT)

A March 14, 2017 news item on ScienceDaily describes a new nanocellulose-based product developed by the Technical Research Centre of Finland (VTT),

VTT Technical Research Centre of Finland Ltd has developed lightweight 100% bio-based stand-up pouches with high technical performance. High performance in both oxygen, grease and mineral oil barrier properties has been reached by using different biobased coatings on paper substrate. The pouches exploit VTT’s patent pending high consistency enzymatic fibrillation of cellulose (HefCel) technology.

A March 14, 2017 VTT press release (also on EurekAlert), which originated the news item, describes why the researchers want to change how food is packaged,

“One-third of food produced for human consumption is lost or wasted globally. Packaging with efficient barrier properties is a crucial factor in the reduction of the food loss. Our solution offers an environmentally friendly option for the global packaging industry”, says Senior Scientist Jari Vartiainen of VTT.

VTT’s HefCel technology provides a low-cost method for the production of nanocellulose resulting in a tenfold increase in the solids content of nanocellulose. Nanocellulose has been shown to be potentially very useful for a number of future technical applications. The densely packed structure of nanocellulose films and coatings enable their outstanding oxygen, grease and mineral oil barrier properties.

HefCel technology exploits industrial enzymes and simple mixing technology as tools to fibrillate cellulose into nanoscale fibrils without the need for high energy consuming process steps. The resulting nanocellulose is in the consistency of 15-25% when traditional nanocellulose production methods result in 1-3% consistency.

The stand-up pouch is the fastest growing type of packaging, growing at a rate of 6.5% per year from 2015-2020. Fossil-based plastic films still dominate the packaging market. However, the development of environmentally friendly new materials is of growing importance. Nanocellulose has been shown to be potentially very useful for a number of future technical applications.

VTT has solid expertise in various bio-based raw materials and their application technologies for producing bio-based coatings, films and even multilayered structures both at lab-scale and pilot-scale. A versatile set of piloting facilities are available from raw material sourcing through processing to application testing and demonstration.

I’m glad to hear they’re finding uses for nanocellulose and I keep wondering when Canadian scientists who at one point were leaders in developing crystal nanocellulose (CNC or sometimes known as nanocrystalline cellulose [NCC]) will be making announcements about potential products.

The Swiss come to a better understanding of nanomaterials

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Just to keep things interesting, after the report suggesting most of the information that the OECD (Organization for Economic Cooperation and Development) has on nanomaterials is of little value for determining risk (see my April 5, 2017 posting for more) the Swiss government has released a report where they claim an improved understanding of nanomaterials than they previously had due to further research into the matter. From an April 6, 2017 news item on Nanowerk,

In the past six years, the [Swiss] National Research Programme “Opportunities and Risks of Nanomaterials” (NRP 64) intensively studied the development, use, behaviour and degradation of engineered nanomaterials, including their impact on humans and on the environment.

Twenty-three research projects on biomedicine, the environment, energy, construction materials and food demonstrated the enormous potential of engineered nanoparticles for numerous applications in industry and medicine. Thanks to these projects we now know a great deal more about the risks associated with nanomaterials and are therefore able to more accurately determine where and how they can be safely used.

An April 6, 2017 Swiss National Science Foundation press release, which originated the news item, expands on the theme,

“One of the specified criteria in the programme was that every project had to examine both the opportunities and the risks, and in some cases this was a major challenge for the researchers,” explains Peter Gehr, President of the NRP 64 Steering Committee.

One development that is nearing industrial application concerns a building material strengthened with nanocellulose that can be used to produce a strong but lightweight insulation material. Successful research was also carried out in the area of energy, where the aim was to find a way to make lithium-ion batteries safer and more efficient.

Promising outlook for nanomedicine

A great deal of potential is predicted for the field of nanomedicine. Nine of the 23 projects in NRP 64 focused on biomedical applications of nanoparticles. These include their use for drug delivery, for example in the fight against viruses, or as immune modulators in a vaccine against asthma. Another promising application concerns the use of nanomagnets for filtering out harmful metallic substances from the blood. One of the projects demonstrated that certain nanoparticles can penetrate the placenta barrier, which points to potential new therapy options. The potential of cartilage and bone substitute materials based on nanocellulose or nanofibres was also studied.

The examination of potential health risks was the focus of NRP 64. A number of projects examined what happens when nanoparticles are inhaled, while two focused on ingestion. One of these investigated whether the human gut is able to absorb iron more efficiently if it is administered in the form of iron nanoparticles in a food additive, while the other studied silicon nanoparticles as they occur in powdered condiments. It was ascertained that further studies will be required in order to determine the doses that can be used without risking an inflammatory reaction in the gut.

What happens to engineered nanomaterials in the environment?

The aim of the seven projects focusing on environmental impact was to gain a better understanding of the toxicity of nanomaterials and their degradability, stability and accumulation in the environment and in biological systems. Here, the research teams monitored how engineered nanoparticles disseminate along their lifecycle, and where they end up or how they can be discarded.

One of the projects established that 95 per cent of silver nanoparticles that are washed out of textiles are collected in sewage treatment plants, while the remaining particles end up in sewage sludge, which in Switzerland is incinerated. In another project a measurement device was developed to determine how aquatic microorganisms react when they come into contact with nanoparticles.

Applying results and making them available to industry

“The findings of the NRP 64 projects form the basis for a safe application of nanomaterials,” says Christoph Studer from the Federal Office of Public Health. “It has become apparent that regulatory instruments such as testing guidelines will have to be adapted at both national and international level.” Studer has been closely monitoring the research programme in his capacity as the Swiss government’s representative in NRP 64. In this context, the precautionary matrix developed by the government is an important instrument by means of which companies can systematically assess the risks associated with the use of nanomaterials in their production processes.

The importance of standardised characterisation and evaluation of engineered nanomaterials was highlighted by the close cooperation among researchers in the programme. “The research network that was built up in the framework of NRP 64 is functioning smoothly and needs to be further nurtured,” says Professor Bernd Nowack from Empa, who headed one of the 23 projects.

The results of NRP 64 show that new key technologies such as the use of nanomaterials need to be closely monitored through basic research due to the lack of data on its long-term effects. As Peter Gehr points out, “We now know a lot more about the risks of nanomaterials and how to keep them under control. However, we need to conduct additional research to learn what happens when humans and the environment are exposed to engineered nanoparticles over longer periods, or what happens a long time after a one-off exposure.”

You can find out more about the Opportunities and Risks of Nanomaterials; National Research Programme (NRP 64) here.

Harvard University announced new Center on Nano-safety Research

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The nano safety center at Harvard University (Massachusetts, US) is a joint center with the US National Institute of Environmental Health  Sciences according to an Aug. 29, 2016 news item on Nanowerk,

Engineered nanomaterials (ENMs)—which are less than 100 nanometers (one millionth of a millimeter) in diameter—can make the colors in digital printer inks pop and help sunscreens better protect against radiation, among many other applications in industry and science. They may even help prevent infectious diseases. But as the technology becomes more widespread, questions remain about the potential risks that ENMs may pose to health and the environment.

Researchers at the new Harvard-NIEHS [US National Institute of Environmental Health Sciences] Nanosafety Research Center at Harvard T.H. Chan School of Public Health are working to understand the unique properties of ENMs—both beneficial and harmful—and to ultimately establish safety standards for the field.

An Aug. 16, 2016 Harvard University press release, which originated the news item, provides more detail (Note: Links have been removed),

“We want to help nanotechnology develop as a scientific and economic force while maintaining safeguards for public health,” said Center Director Philip Demokritou, associate professor of aerosol physics at Harvard Chan School. “If you understand the rules of nanobiology, you can design safer nanomaterials.”

ENMs can enter the body through inhalation, ingestion, and skin contact, and toxicological studies have shown that some can penetrate cells and tissues and potentially cause biochemical damage. Because the field of nanoparticle science is relatively new, no standards currently exist for assessing the health risks of exposure to ENMs—or even for how studies of nano-biological interactions should be conducted.

Much of the work of the new Center will focus on building a fundamental understanding of why some ENMs are potentially more harmful than others. The team will also establish a “reference library” of ENMs, each with slightly varied properties, which will be utilized in nanotoxicology research across the country to assess safety. This will allow researchers to pinpoint exactly what aspect of an ENM’s properties may impact health. The researchers will also work to develop standardized methods for nanotoxicology studies evaluating the safety of nanomaterials.

The Center was established with a $4 million dollar grant from the National Institute of Environmental Health Science (NIEHS) last month, and is the only nanosafety research center to receive NIEHS funding for the next five years. It will also play a coordinating role with existing and future NIEHS nanotoxicology research projects nantionwide. Scientists from the Harvard John A. Paulson School of Engineering and Applied Sciences (SEAS), MIT, University of Maine, and University of Florida will collaborate on the new effort.

The Center builds on the existing Center for Nanotechnology and Nanotoxicology at Harvard Chan School, established by Demokritou and Joseph Brain, Cecil K. and Philip Drinker Professor of Environmental Physiology, in the School’s Department of Environmental Health in 2010.

A July 5, 2016 Harvard University press release announcing the $4M grant provides more information about which ENMs are to be studied,

The main focus of the new HSPH-NIEHS Center is to bring together  scientists from across disciplines- material science, chemistry, exposure assessment, risk assessment, nanotoxicology and nanobiology- to assess the potential  environmental Health and safety (EHS) implications of engineered nanomaterials (ENMs).

The $4 million dollar HSPH based Center  which is the only Nanosafety Research  Center to be funded by NIEHS this funding cycle, … The new HSPH-NIEHS Nanosafety Center builds upon the nano-related infrastructure in [the] collaborating Universities, developed over the past 10 years, which includes an inter-disciplinary research group of faculty, research staff and students, as well as state-of-the-art platforms for high throughput synthesis of ENMs, including metal and metal oxides, cutting edge 2D/3D ENMs such as CNTs [carbon nanotubes] and graphene, nanocellulose, and advanced nanocomposites, [emphasis mine] coupled with innovative tools to assess the fate and transport of ENMs in biological systems, statistical and exposure assessment tools, and novel in vitro and in vivo platforms for nanotoxicology research.

“Our mission is to integrate material/exposure/chemical sciences and nanotoxicology-nanobiology   to facilitate assessment of potential risks from emerging nanomaterials.  In doing so, we are bringing together the material synthesis/applications and nanotoxicology communities and other stakeholders including industry,   policy makers and the general public to maximize innovation and growth and minimize environmental and public health risks from nanotechnology”, quoted by  Dr Philip Demokritou, …

This effort certainly falls in line with the current emphasis on interdisciplinary research and creating standards and protocols for researching the toxicology of engineered nanomaterials.