Tag Archives: cellulose

Gamechanging electronics with new ultrafast, flexible, and transparent electronics

There are two news bits about game-changing electronics, one from the UK and the other from the US.

United Kingdom (UK)

An April 3, 2017 news item on Azonano announces the possibility of a future golden age of electronics courtesy of the University of Exeter,

Engineering experts from the University of Exeter have come up with a breakthrough way to create the smallest, quickest, highest-capacity memories for transparent and flexible applications that could lead to a future golden age of electronics.

A March 31, 2017 University of Exeter press release (also on EurekAlert), which originated the news item, expands on the theme (Note: Links have been removed),

Engineering experts from the University of Exeter have developed innovative new memory using a hybrid of graphene oxide and titanium oxide. Their devices are low cost and eco-friendly to produce, are also perfectly suited for use in flexible electronic devices such as ‘bendable’ mobile phone, computer and television screens, and even ‘intelligent’ clothing.

Crucially, these devices may also have the potential to offer a cheaper and more adaptable alternative to ‘flash memory’, which is currently used in many common devices such as memory cards, graphics cards and USB computer drives.

The research team insist that these innovative new devices have the potential to revolutionise not only how data is stored, but also take flexible electronics to a new age in terms of speed, efficiency and power.

Professor David Wright, an Electronic Engineering expert from the University of Exeter and lead author of the paper said: “Using graphene oxide to produce memory devices has been reported before, but they were typically very large, slow, and aimed at the ‘cheap and cheerful’ end of the electronics goods market.

“Our hybrid graphene oxide-titanium oxide memory is, in contrast, just 50 nanometres long and 8 nanometres thick and can be written to and read from in less than five nanoseconds – with one nanometre being one billionth of a metre and one nanosecond a billionth of a second.”

Professor Craciun, a co-author of the work, added: “Being able to improve data storage is the backbone of tomorrow’s knowledge economy, as well as industry on a global scale. Our work offers the opportunity to completely transform graphene-oxide memory technology, and the potential and possibilities it offers.”

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

Multilevel Ultrafast Flexible Nanoscale Nonvolatile Hybrid Graphene Oxide–Titanium Oxide Memories by V. Karthik Nagareddy, Matthew D. Barnes, Federico Zipoli, Khue T. Lai, Arseny M. Alexeev, Monica Felicia Craciun, and C. David Wright. ACS Nano, 2017, 11 (3), pp 3010–3021 DOI: 10.1021/acsnano.6b08668 Publication Date (Web): February 21, 2017

Copyright © 2017 American Chemical Society

This paper appears to be open access.

United States (US)

Researchers from Stanford University have developed flexible, biodegradable electronics.

A newly developed flexible, biodegradable semiconductor developed by Stanford engineers shown on a human hair. (Image credit: Bao lab)

A human hair? That’s amazing and this May 3, 2017 news item on Nanowerk reveals more,

As electronics become increasingly pervasive in our lives – from smart phones to wearable sensors – so too does the ever rising amount of electronic waste they create. A United Nations Environment Program report found that almost 50 million tons of electronic waste were thrown out in 2017–more than 20 percent higher than waste in 2015.

Troubled by this mounting waste, Stanford engineer Zhenan Bao and her team are rethinking electronics. “In my group, we have been trying to mimic the function of human skin to think about how to develop future electronic devices,” Bao said. She described how skin is stretchable, self-healable and also biodegradable – an attractive list of characteristics for electronics. “We have achieved the first two [flexible and self-healing], so the biodegradability was something we wanted to tackle.”

The team created a flexible electronic device that can easily degrade just by adding a weak acid like vinegar. The results were published in the Proceedings of the National Academy of Sciences (“Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics”).

“This is the first example of a semiconductive polymer that can decompose,” said lead author Ting Lei, a postdoctoral fellow working with Bao.

A May 1, 2017 Stanford University news release by Sarah Derouin, which originated the news item, provides more detail,

In addition to the polymer – essentially a flexible, conductive plastic – the team developed a degradable electronic circuit and a new biodegradable substrate material for mounting the electrical components. This substrate supports the electrical components, flexing and molding to rough and smooth surfaces alike. When the electronic device is no longer needed, the whole thing can biodegrade into nontoxic components.

Biodegradable bits

Bao, a professor of chemical engineering and materials science and engineering, had previously created a stretchable electrode modeled on human skin. That material could bend and twist in a way that could allow it to interface with the skin or brain, but it couldn’t degrade. That limited its application for implantable devices and – important to Bao – contributed to waste.

Flexible, biodegradable semiconductor on an avacado

The flexible semiconductor can adhere to smooth or rough surfaces and biodegrade to nontoxic products. (Image credit: Bao lab)

Bao said that creating a robust material that is both a good electrical conductor and biodegradable was a challenge, considering traditional polymer chemistry. “We have been trying to think how we can achieve both great electronic property but also have the biodegradability,” Bao said.

Eventually, the team found that by tweaking the chemical structure of the flexible material it would break apart under mild stressors. “We came up with an idea of making these molecules using a special type of chemical linkage that can retain the ability for the electron to smoothly transport along the molecule,” Bao said. “But also this chemical bond is sensitive to weak acid – even weaker than pure vinegar.” The result was a material that could carry an electronic signal but break down without requiring extreme measures.

In addition to the biodegradable polymer, the team developed a new type of electrical component and a substrate material that attaches to the entire electronic component. Electronic components are usually made of gold. But for this device, the researchers crafted components from iron. Bao noted that iron is a very environmentally friendly product and is nontoxic to humans.

The researchers created the substrate, which carries the electronic circuit and the polymer, from cellulose. Cellulose is the same substance that makes up paper. But unlike paper, the team altered cellulose fibers so the “paper” is transparent and flexible, while still breaking down easily. The thin film substrate allows the electronics to be worn on the skin or even implanted inside the body.

From implants to plants

The combination of a biodegradable conductive polymer and substrate makes the electronic device useful in a plethora of settings – from wearable electronics to large-scale environmental surveys with sensor dusts.

“We envision these soft patches that are very thin and conformable to the skin that can measure blood pressure, glucose value, sweat content,” Bao said. A person could wear a specifically designed patch for a day or week, then download the data. According to Bao, this short-term use of disposable electronics seems a perfect fit for a degradable, flexible design.

And it’s not just for skin surveys: the biodegradable substrate, polymers and iron electrodes make the entire component compatible with insertion into the human body. The polymer breaks down to product concentrations much lower than the published acceptable levels found in drinking water. Although the polymer was found to be biocompatible, Bao said that more studies would need to be done before implants are a regular occurrence.

Biodegradable electronics have the potential to go far beyond collecting heart disease and glucose data. These components could be used in places where surveys cover large areas in remote locations. Lei described a research scenario where biodegradable electronics are dropped by airplane over a forest to survey the landscape. “It’s a very large area and very hard for people to spread the sensors,” he said. “Also, if you spread the sensors, it’s very hard to gather them back. You don’t want to contaminate the environment so we need something that can be decomposed.” Instead of plastic littering the forest floor, the sensors would biodegrade away.

As the number of electronics increase, biodegradability will become more important. Lei is excited by their advancements and wants to keep improving performance of biodegradable electronics. “We currently have computers and cell phones and we generate millions and billions of cell phones, and it’s hard to decompose,” he said. “We hope we can develop some materials that can be decomposed so there is less waste.”

Other authors on the study include Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister McGuire, and Jeffrey Tok of Stanford University; Tsung-Ching Huang of Hewlett Packard Enterprise; and Lei-Lai Shao and Kwang-Ting Cheng of University of California, Santa Barbara.

The research was funded by the Air Force Office for Scientific Research; BASF; Marie Curie Cofund; Beatriu de Pinós fellowship; and the Kodak Graduate Fellowship.

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

Biocompatible and totally disintegrable semiconducting polymer for ultrathin and ultralightweight transient electronics by Ting Lei, Ming Guan, Jia Liu, Hung-Cheng Lin, Raphael Pfattner, Leo Shaw, Allister F. McGuire, Tsung-Ching Huang, Leilai Shao, Kwang-Ting Cheng, Jeffrey B.-H. Tok, and Zhenan Bao. PNAS 2017 doi: 10.1073/pnas.1701478114 published ahead of print May 1, 2017

This paper is behind a paywall.

The mention of cellulose in the second item piqued my interest so I checked to see if they’d used nanocellulose. No, they did not. Microcrystalline cellulose powder was used to constitute a cellulose film but they found a way to render this film at the nanoscale. From the Stanford paper (Note: Links have been removed),

… Moreover, cellulose films have been previously used as biodegradable substrates in electronics (28⇓–30). However, these cellulose films are typically made with thicknesses well over 10 μm and thus cannot be used to fabricate ultrathin electronics with substrate thicknesses below 1–2 μm (7, 18, 19). To the best of our knowledge, there have been no reports on ultrathin (1–2 μm) biodegradable substrates for electronics. Thus, to realize them, we subsequently developed a method described herein to obtain ultrathin (800 nm) cellulose films (Fig. 1B and SI Appendix, Fig. S8). First, microcrystalline cellulose powders were dissolved in LiCl/N,N-dimethylacetamide (DMAc) and reacted with hexamethyldisilazane (HMDS) (31, 32), providing trimethylsilyl-functionalized cellulose (TMSC) (Fig. 1B). To fabricate films or devices, TMSC in chlorobenzene (CB) (70 mg/mL) was spin-coated on a thin dextran sacrificial layer. The TMSC film was measured to be 1.2 μm. After hydrolyzing the film in 95% acetic acid vapor for 2 h, the trimethylsilyl groups were removed, giving a 400-nm-thick cellulose film. The film thickness significantly decreased to one-third of the original film thickness, largely due to the removal of the bulky trimethylsilyl groups. The hydrolyzed cellulose film is insoluble in most organic solvents, for example, toluene, THF, chloroform, CB, and water. Thus, we can sequentially repeat the above steps to obtain an 800-nm-thick film, which is robust enough for further device fabrication and peel-off. By soaking the device in water, the dextran layer is dissolved, starting from the edges of the device to the center. This process ultimately releases the ultrathin substrate and leaves it floating on water surface (Fig. 3A, Inset).

Finally, I don’t have any grand thoughts; it’s just interesting to see different approaches to flexible electronics.

3D printing with cellulose

The scientists seem quite excited about their work with 3D printing and cellulose. From a March 3, 2017 MIT (Massachusetts Institute of Technology) news release (also on EurekAlert),

For centuries, cellulose has formed the basis of the world’s most abundantly printed-on material: paper. Now, thanks to new research at MIT, it may also become an abundant material to print with — potentially providing a renewable, biodegradable alternative to the polymers currently used in 3-D printing materials.

“Cellulose is the most abundant organic polymer in the world,” says MIT postdoc Sebastian Pattinson, lead author of a paper describing the new system in the journal Advanced Materials Technologies. The paper is co-authored by associate professor of mechanical engineering A. John Hart, the Mitsui Career Development Professor in Contemporary Technology.

Cellulose, Pattinson explains, is “the most important component in giving wood its mechanical properties. And because it’s so inexpensive, it’s biorenewable, biodegradable, and also very chemically versatile, it’s used in a lot of products. Cellulose and its derivatives are used in pharmaceuticals, medical devices, as food additives, building materials, clothing — all sorts of different areas. And a lot of these kinds of products would benefit from the kind of customization that additive manufacturing [3-D printing] enables.”

Meanwhile, 3-D printing technology is rapidly growing. Among other benefits, it “allows you to individually customize each product you make,” Pattinson says.

Using cellulose as a material for additive manufacturing is not a new idea, and many researchers have attempted this but faced major obstacles. When heated, cellulose thermally decomposes before it becomes flowable, partly because of the hydrogen bonds that exist between the cellulose molecules. The intermolecular bonding also makes high-concentration cellulose solutions too viscous to easily extrude.

Instead, the MIT team chose to work with cellulose acetate — a material that is easily made from cellulose and is already widely produced and readily available. Essentially, the number of hydrogen bonds in this material has been reduced by the acetate groups. Cellulose acetate can be dissolved in acetone and extruded through a nozzle. As the acetone quickly evaporates, the cellulose acetate solidifies in place. A subsequent optional treatment replaces the acetate groups and increases the strength of the printed parts.

“After we 3-D print, we restore the hydrogen bonding network through a sodium hydroxide treatment,” Pattinson says. “We find that the strength and toughness of the parts we get … are greater than many commonly used materials” for 3-D printing, including acrylonitrile butadiene styrene (ABS) and polylactic acid (PLA).

To demonstrate the chemical versatility of the production process, Pattinson and Hart added an extra dimension to the innovation. By adding a small amount of antimicrobial dye to the cellulose acetate ink, they 3-D-printed a pair of surgical tweezers with antimicrobial functionality.

“We demonstrated that the parts kill bacteria when you shine fluorescent light on them,” Pattinson says. Such custom-made tools “could be useful for remote medical settings where there’s a need for surgical tools but it’s difficult to deliver new tools as they break, or where there’s a need for customized tools. And with the antimicrobial properties, if the sterility of the operating room is not ideal the antimicrobial function could be essential,” he says.

Because most existing extrusion-based 3-D printers rely on heating polymer to make it flow, their production speed is limited by the amount of heat that can be delivered to the polymer without damaging it. This room-temperature cellulose process, which simply relies on evaporation of the acetone to solidify the part, could potentially be faster, Pattinson says. And various methods could speed it up even further, such as laying down thin ribbons of material to maximize surface area, or blowing hot air over it to speed evaporation. A production system would also seek to recover the evaporated acetone to make the process more cost effective and environmentally friendly.

Cellulose acetate is already widely available as a commodity product. In bulk, the material is comparable in price to that of thermoplastics used for injection molding, and it’s much less expensive than the typical filament materials used for 3-D printing, the researchers say. This, combined with the room-temperature conditions of the process and the ability to functionalize cellulose in a variety of ways, could make it commercially attractive.

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

Additive Manufacturing of Cellulosic Materials with Robust Mechanics and Antimicrobial Functionality by Sebastian W. Pattinson and A. John Hart. Advanced Materials Technologies DOI: 10.1002/admt.201600084 Version of Record online: 30 JAN 2017

© 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

nano tech 2017 being held in Tokyo from February 15-17, 2017

I found some news about the Alberta technology scene in the programme for Japan’s nano tech 2017 exhibition and conference to be held Feb. 15 – 17, 2017 in Tokyo. First, here’s more about the show in Japan from a Jan. 17, 2017 nano tech 2017 press release on Business Wire (also on Yahoo News),

The nano tech executive committee (chairman: Tomoji Kawai, Specially Appointed Professor, Osaka University) will be holding “nano tech 2017” – one of the world’s largest nanotechnology exhibitions, now in its 16th year – on February 15, 2017, at the Tokyo Big Sight convention center in Japan. 600 organizations (including over 40 first-time exhibitors) from 23 countries and regions are set to exhibit at the event in 1,000 booths, demonstrating revolutionary and cutting edge core technologies spanning such industries as automotive, aerospace, environment/energy, next-generation sensors, cutting-edge medicine, and more. Including attendees at the concurrently held exhibitions, the total number of visitors to the event is expected to exceed 50,000.

The theme of this year’s nano tech exhibition is “Open Nano Collaboration.” By bringing together organizations working in a wide variety of fields, the business matching event aims to promote joint development through cross-field collaboration.

Special Symposium: “Nanotechnology Contributing to the Super Smart Society”

Each year nano tech holds Special Symposium, in which industry specialists from top organizations from Japan and abroad speak about the issues surrounding the latest trends in nanotech. The themes of this year’s Symposium are Life Nanotechnology, Graphene, AI/IoT, Cellulose Nanofibers, and Materials Informatics.

Notable sessions include:

Life Nanotechnology
“Development of microRNA liquid biopsy for early detection of cancer”
Takahiro Ochiya, National Cancer Center Research Institute Division of Molecular and Cellular Medicine, Chief

AI / IoT
“AI Embedded in the Real World”
Hideki Asoh, AIST Deputy Director, Artificial Intelligence Research Center

Cellulose Nanofibers [emphasis mine]
“The Current Trends and Challenges for Industrialization of Nanocellulose”
Satoshi Hirata, Nanocellulose Forum Secretary-General

Materials Informatics
“Perspective of Materials Research”
Hideo Hosono, Tokyo Institute of Technology Professor

View the full list of sessions:
>> http://nanotech2017.icsbizmatch.jp/Presentation/en/Info/List#main_theater

nano tech 2017 Homepage:
>> http://nanotechexpo.jp/

nano tech 2017, the 16th International Nanotechnology Exhibition & Conference
Date: February 15-17, 2017, 10:00-17:00
Venue: Tokyo Big Sight (East Halls 4-6 & Conference Tower)
Organizer: nano tech Executive Committee, JTB Communication Design

As you may have guessed the Alberta information can be found in the .Cellulose Nanofibers session. From the conference/seminar program page; scroll down about 25% of the way to find the Alberta presentation,

Production and Applications Development of Cellulose Nanocrystals (CNC) at InnoTech Alberta

Behzad (Benji) Ahvazi
InnoTech Alberta Team Lead, Cellulose Nanocrystals (CNC)

[ Abstract ]

The production and use of cellulose nanocrystals (CNC) is an emerging technology that has gained considerable interest from a range of industries that are working towards increased use of “green” biobased materials. The construction of one-of-a-kind CNC pilot plant [emphasis mine] at InnoTech Alberta and production of CNC samples represents a critical step for introducing the cellulosic based biomaterials to industrial markets and provides a platform for the development of novel high value and high volume applications. Major key components including feedstock, acid hydrolysis formulation, purification, and drying processes were optimized significantly to reduce the operation cost. Fully characterized CNC samples were provided to a large number of academic and research laboratories including various industries domestically and internationally for applications development.

[ Profile ]

Dr. Ahvazi completed his Bachelor of Science in Honours program at the Department of Chemistry and Biochemistry and graduated with distinction at Concordia University in Montréal, Québec. His Ph.D. program was completed in 1998 at McGill Pulp and Paper Research Centre in the area of macromolecules with solid background in Lignocellulosic, organic wood chemistry as well as pulping and paper technology. After completing his post-doctoral fellowship, he joined FPInnovations formally [formerly?] known as PAPRICAN as a research scientist (R&D) focusing on a number of confidential chemical pulping and bleaching projects. In 2006, he worked at Tembec as a senior research scientist and as a Leader in Alcohol and Lignin (R&D). In April 2009, he held a position as a Research Officer in both National Bioproducts (NBP1 & NBP2) and Industrial Biomaterials Flagship programs at National Research Council Canada (NRC). During his tenure, he had directed and performed innovative R&D activities within both programs on extraction, modification, and characterization of biomass as well as polymer synthesis and formulation for industrial applications. Currently, he is working at InnoTech Alberta as Team Lead for Biomass Conversion and Processing Technologies.

Canada scene update

InnoTech Alberta was until Nov. 1, 2016 known as Alberta Innovates – Technology Futures. Here’s more about InnoTech Alberta from the Alberta Innovates … home page,

Effective November 1, 2016, Alberta Innovates – Technology Futures is one of four corporations now consolidated into Alberta Innovates and a wholly owned subsidiary called InnoTech Alberta.

You will find all the existing programs, services and information offered by InnoTech Alberta on this website. To access the basic research funding and commercialization programs previously offered by Alberta Innovates – Technology Futures, explore here. For more information on Alberta Innovates, visit the new Alberta Innovates website.

As for InnoTech Alberta’s “one-of-a-kind CNC pilot plant,” I’d like to know more about it’s one-of-a-kind status since there are two other CNC production plants in Canada. (Is the status a consequence of regional chauvinism or a writer unfamiliar with the topic?). Getting back to the topic, the largest company (and I believe the first) with a CNC plant was CelluForce, which started as a joint venture between Domtar and FPInnovations and powered with some very heavy investment from the government of Canada. (See my July 16, 2010 posting about the construction of the plant in Quebec and my June 6, 2011 posting about the newly named CelluForce.) Interestingly, CelluForce will have a booth at nano tech 2017 (according to its Jan. 27, 2017 news release) although the company doesn’t seem to have any presentations on the schedule. The other Canadian company is Blue Goose Biorefineries in Saskatchewan. Here’s more about Blue Goose from the company website’s home page,

Blue Goose Biorefineries Inc. (Blue Goose) is pleased to introduce our R3TM process. R3TM technology incorporates green chemistry to fractionate renewable plant biomass into high value products.

Traditionally, separating lignocellulosic biomass required high temperatures, harsh chemicals, and complicated processes. R3TM breaks this costly compromise to yield high quality cellulose, lignin and hemicellulose products.

The robust and environmentally friendly R3TM technology has numerous applications. Our current product focus is cellulose nanocrystals (CNC). Cellulose nanocrystals are “Mother Nature’s Building Blocks” possessing unique properties. These unique properties encourage the design of innovative products from a safe, inherently renewable, sustainable, and carbon neutral resource.

Blue Goose assists companies and research groups in the development of applications for CNC, by offering CNC for sale without Intellectual Property restrictions. [emphasis mine]

Bravo to Blue Goose! Unfortunately, I was not able to determine if the company will be at nano tech 2017.

One final comment, there was some excitement about CNC a while back where I had more than one person contact me asking for information about how to buy CNC. I wasn’t able to be helpful because there was, apparently, an attempt by producers to control sales and limit CNC access to a select few for competitive advantage. Coincidentally or not, CelluForce developed a stockpile which has persisted for some years as I noted in my Aug. 17, 2016 posting (scroll down about 70% of the way) where the company announced amongst other events that it expected deplete its stockpile by mid-2017.

‘Getting into’ cellulose walls at the University of Cambridge (UK) and University of Melbourne (Australia)

“Getting into” as used in the headline is slang for exploring a topic in more depth which is what an international team of researchers did when they ‘got into’ cellulose. From a June 9, 2016 news item on phys.org (Note: Links have been removed),

In the search for low emission plant-based fuels, new research may help avoid having to choose between growing crops for food or fuel.

Scientists have identified new steps in the way plants produce cellulose, the component of plant cell walls that provides strength, and forms insoluble fibre in the human diet.

The findings could lead to improved production of cellulose and guide plant breeding for specific uses such as wood products and ethanol fuel, which are sustainable alternatives to fossil fuel-based products.

Published in the journal Nature Communications today, the work was conducted by an international team of scientists, led by the University of Cambridge and the University of Melbourne.

A June 9, 2016 University of Cambridge press release, which originated the news item, provides more detail,

“Our research identified several proteins that are essential in the assembly of the protein machinery that makes cellulose”, said Melbourne’s Prof Staffan Persson.

“We found that these assembly factors control how much cellulose is made, and so plants without them can not produce cellulose very well and the defect substantially impairs plant biomass production. The ultimate aim of this research would be breed plants that have altered activity of these proteins so that cellulose production can be improved for the range of applications that use cellulose including paper, timber and ethanol fuels.”

The newly discovered proteins are located in an intracellular compartment called the Golgi where proteins are sorted and modified.

“If the function of this protein family is abolished the cellulose synthesizing complexes become stuck in the Golgi and have problems reaching the cell surface where they normally are active” said the lead authors of the study, Drs. Yi Zhang (Max-Planck Institute for Molecular Plant Physiology) and Nino Nikolovski (University of Cambridge).

“We therefore named the new proteins STELLO, which is Greek for to set in place, and deliver.”

“The findings are important to understand how plants produce their biomass”, said Professor Paul Dupree from the University of Cambridge’s Department of Biochemistry.

“Greenhouse-gas emissions from cellulosic ethanol, which is derived from the biomass of plants, are estimated to be roughly 85 percent less than from fossil fuel sources. Research to understand cellulose production in plants is therefore an important part of climate change mitigation.”

“In addition, by using cellulosic plant materials we get around the problem of food-versus-fuel scenario that is problematic when using corn as a basis for bioethanol.”

“It is therefore of great importance to find genes and mechanisms that can improve cellulose production in plants so that we can tailor cellulose production for various needs.”

Previous studies by Profs. Persson’s and Dupree’s research groups have, together with other scientists, identified many proteins that are important for cellulose synthesis and for other cell wall polymers.

With the newly presented research they substantially increase our understanding for how the bulk of a plant’s biomass is produced and is therefore of vast importance to industrial applications.

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

Golgi-localized STELLO proteins regulate the assembly and trafficking of cellulose synthase complexes in Arabidopsis by Yi Zhang, Nino Nikolovski, Mathias Sorieul, Tamara Vellosillo, Heather E. McFarlane, Ray Dupree, Christopher Kesten, René Schneider, Carlos Driemeier, Rahul Lathe, Edwin Lampugnani, Xiaolan Yu, Alexander Ivakov, Monika S. Doblin, Jenny C. Mortimer, Steven P. Brown, Staffan Persson, & Paul Dupree. Nature Communications 7,
Article number: 11656 doi:10.1038/ncomms11656 Published  09 June 2016

This paper is open access.

Biodegradable films from cellulose nanofibrils

A team at Purdue University (Indiana, US) has developed a new process for biodegradable films based on cellulose according to a June 8, 2016 news item on phys.org,

Purdue University researchers have developed tough, flexible, biodegradable films from cellulose, the main component of plant cell walls. The films could be used for products such as food packaging, agricultural groundcovers, bandages and capsules for medicine or bioactive compounds.

Food scientists Srinivas Janaswamy and Qin Xu engineered the cellophane-like material by solubilizing cellulose using zinc chloride, a common inorganic salt, and adding calcium ions to cause the cellulose chains to become tiny fibers known as nanofibrils, greatly increasing the material’s tensile strength. The zinc chloride and calcium ions work together to form a gel network, allowing the researchers to cast the material into a transparent, food-grade film.

A June 7, 2016 Purdue University news release by Natalie van Hoose, which originated the news item, discusses the need for these films and provides a few more technical details about the work (Note: A link has been removed),

“We’re looking for innovative ways to adapt and use cellulose – an inexpensive and widely available material – for a range of food, biomedical and pharmaceutical applications,” said Janaswamy, research assistant professor of food science and principal author of the study. “Though plastics have a wide variety of applications, their detrimental impact on the environment raises a critical need for alternative materials. Cellulose stands out as a viable option, and our process lays a strong foundation for developing new biodegradable plastics.”

Cellulose’s abundance, renewability and ability to biodegrade make it a promising substitute for petroleum-based products. While a variety of products such as paper, cellophane and rayon are made from cellulose, its tightly interlinked structure and insolubility – qualities that give plants strength and protection – make it a challenging material to work with.

Janaswamy and Xu loosened the cellulose network by adding zinc chloride, which helps push cellulose’s closely packed sheets apart, allowing water to penetrate and solubilize it. Adding calcium ions spurs the formation of nanofibrils through strong bonds between the solubilized cellulose sheets. The calcium ions boost the tensile strength of the films by about 250 percent.

The production process preserves the strength and biodegradability of cellulose while rendering it transparent and flexible.

Because the zinc chloride can be recycled to repeat the process, the method offers an environmentally friendly alternative to conventional means of breaking down cellulose, which tend to rely on toxic chemicals and extreme temperatures.

“Products based on this film can have a no-waste lifecycle,” said Xu, research assistant professor of food science and first author of the study. “This process allows us to create a valuable product from natural materials – including low-value or waste materials such as corn stover or wood chips- that can eventually be returned to the Earth.”

The methodology could be adapted to mass-produce cellulose films, the researchers said.

The next step in the project is to find ways of making the cellulose film insoluble to water while maintaining its ability to biodegrade.

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

A facile route to prepare cellulose-based films by Qin Xu, Chen Chen, Katelyn Rosswurm, Tianming Yao, Srinivas Janaswamy. Carbohydrate Polymers Volume 149, 20 September 2016, Pages 274–281 doi:10.1016/j.carbpol.2016.04.114

This paper is behind a paywall.

Inside-out plants show researchers how cellulose forms

Strictly speaking this story of tricking cellulose into growing on the surface rather than the interior of a cell is not a nanotechnology topic but I imagine that the folks who research nanocellulose materials will find this work of great interest. An Oct. 8, 2015 news item on ScienceDaily describes the research,

Researchers have been able to watch the interior cells of a plant synthesize cellulose for the first time by tricking the cells into growing on the plant’s surface.

“The bulk of the world’s cellulose is produced within the thickened secondary cell walls of tissues hidden inside the plant body,” says University of British Columbia Botany PhD candidate Yoichiro Watanabe, lead author of the paper published this week in Science.

“So we’ve never been able to image the cells in high resolution as they produce this all-important biological material inside living plants.”

An Oct. 8, 2015 University of British Columbia (UBC) news release on EurekAlert, which originated the news item, explains the interest in cellulose,

Cellulose, the structural component of cell walls that enables plants to stay upright, is the most abundant biopolymer on earth. It’s a critical resource for pulp and paper, textiles, building materials, and renewable biofuels.

“In order to be structurally sound, plants have to lay down their secondary cell walls very quickly once the plant has stopped growing, like a layer of concrete with rebar,” says UBC botanist Lacey Samuels, one of the senior authors on the paper.

“Based on our study, it appears plant cells need both a high density of the enzymes that create cellulose, and their rapid movement across the cell surface, to make this happen so quickly.”

This work, the culmination of years of research by four UBC graduate students supervised by UBC Forestry researcher Shawn Mansfield and Samuels, was facilitated by a collaboration with the Nara Institute of Technology in Japan to create the special plant lines, and researchers at the Carnegie Institution for Science at Stanford University to conduct the live cell imaging.

“This is a major step forward in our understanding of how plants synthesize their walls, specifically cellulose,” says Mansfield. “It could have significant implications for the way plants are bred or selected for improved or altered cellulose ultrastructural traits – which could impact industries ranging from cellulose nanocrystals to toiletries to structural building products.”

The researchers used a modified line of Arabidopsis thaliana, a small flowering plant related to cabbage and mustard, to conduct the experiment. The resulting plants look exactly like their non-modified parents, until they are triggered to make secondary cell walls on their exterior.

One of the other partners in this research, Stanford University’s Carnegie Institution of Science published an Oct. 8, 2015 news release on EurekAlert focusing on other aspects of the research (Note: Some of this is repetitive),

Now scientists, including Carnegie’s David Ehrhardt and Heather Cartwright, have exploited a new way to watch the trafficking of the proteins that make cellulose in the formation cell walls in real time. They found that organization of this trafficking by structural proteins called microtubules, combined with the high density and rapid rate of these cellulose producing enzymes explains how thick and high strength secondary walls are built. This basic knowledge helps us understand plants can stand upright, which was essential for the move of plants from the sea to the land, and may useful for engineering plants with improved mechanical properties for to increase yields or to produce novel bio-materials. The research is published in Science.

The live-cell imaging was conducted at Carnegie with colleagues from the University of British Columbia (UBC) using customized high-end instrumentation. For the first time, it directly tracked cellulose production to observe how xylem cells, cells that transport water and some nutrients, make cellulose for their secondary cell walls. Strong walls are based on a high density of enzymes that catalyze the synthesis of cellulose (called cellulose synthase enzymes) and their rapid movement across the xylem cell surface.

Watching xylem cells lay down cellulose in real time has not been possible before, because the vascular tissues of plants are hidden inside the plant body. Lead author Yoichiro Watanabe of UBC applied a system developed by colleagues at the Nara Institute of Science and Technology to trick plants into making xylem cells on their surface. The researchers fluorescently tagged a cellulose synthase enzyme of the experimental plant Arabidopsis to track the activity using high-end microscopes.

“For me, one of the most exciting aspects of this study was being able to observe how the microtubule cytoskeleton was actively directing the synthesis of the new cell walls at the level of individual enzymes. We can guess how a complex cellular process works from static snapshots, which is what we usually have had to work from in biology, but you can’t really understand the process until you can see it in action. ” remarked Carnegie’s David Ehrhardt.

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

Visualization of cellulose synthases in Arabidopsis secondary cell walls by Y. Watanabe, M. J. Meents, L. M. McDonnell, S. Barkwill, A. Sampathkumar, H. N. Cartwright, T. Demura, D. W. Ehrhardt, A.L. Samuels, & S. D. Mansfield. Science 9 October 2015: Vol. 350 no. 6257 pp. 198-203 DOI: 10.1126/science.aac7446

This paper is behind a paywall.

With all of this talk of visualization, it’s only right that the researchers have made an image from their work available,

 Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.

Caption: An image of artificially-produced cellulose in cells on the surface of a modified Arabidopsis thaliana plant. Credit: University of British Columbia.

 

Replacing metal with nanocellulose paper

The quest to find uses for nanocellulose materials has taken a step forward with some work coming from the University of Maryland (US). From a July 24, 2015 news item on Nanowerk,

Researchers at the University of Maryland recently discovered that paper made of cellulose fibers is tougher and stronger the smaller the fibers get … . For a long time, engineers have sought a material that is both strong (resistant to non-recoverable deformation) and tough (tolerant of damage).

“Strength and toughness are often exclusive to each other,” said Teng Li, associate professor of mechanical engineering at UMD. “For example, a stronger material tends to be brittle, like cast iron or diamond.”

A July 23, 2015 University of Maryland news release, which originated the news item, provides details about the thinking which buttresses this research along with some details about the research itself,

The UMD team pursued the development of a strong and tough material by exploring the mechanical properties of cellulose, the most abundant renewable bio-resource on Earth. Researchers made papers with several sizes of cellulose fibers – all too small for the eye to see – ranging in size from about 30 micrometers to 10 nanometers. The paper made of 10-nanometer-thick fibers was 40 times tougher and 130 times stronger than regular notebook paper, which is made of cellulose fibers a thousand times larger.

“These findings could lead to a new class of high performance engineering materials that are both strong and tough, a Holy Grail in materials design,” said Li.

High performance yet lightweight cellulose-based materials might one day replace conventional structural materials (i.e. metals) in applications where weight is important. This could lead, for example, to more energy efficient and “green” vehicles. In addition, team members say, transparent cellulose nanopaper may become feasible as a functional substrate in flexible electronics, resulting in paper electronics, printable solar cells and flexible displays that could radically change many aspects of daily life.

Cellulose fibers can easily form many hydrogen bonds. Once broken, the hydrogen bonds can reform on their own—giving the material a ‘self-healing’ quality. The UMD discovered that the smaller the cellulose fibers, the more hydrogen bonds per square area. This means paper made of very small fibers can both hold together better and re-form more quickly, which is the key for cellulose nanopaper to be both strong and tough.

“It is helpful to know why cellulose nanopaper is both strong and tough, especially when the underlying reason is also applicable to many other materials,” said Liangbing Hu, assistant professor of materials science at UMD.

To confirm, the researchers tried a similar experiment using carbon nanotubes that were similar in size to the cellulose fibers. The carbon nanotubes had much weaker bonds holding them together, so under tension they did not hold together as well. Paper made of carbon nanotubes is weak, though individually nanotubes are arguably the strongest material ever made.

One possible future direction for the research is the improvement of the mechanical performance of carbon nanotube paper.

“Paper made of a network of carbon nanotubes is much weaker than expected,” said Li. “Indeed, it has been a grand challenge to translate the superb properties of carbon nanotubes at nanoscale to macroscale. Our research findings shed light on a viable approach to addressing this challenge and achieving carbon nanotube paper that is both strong and tough.”

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

Anomalous scaling law of strength and toughness of cellulose nanopaper by Hongli Zhu, Shuze Zhu, Zheng Jia, Sepideh Parvinian, Yuanyuan Li, Oeyvind Vaaland, Liangbing Hu, and Teng Li. PNAS (Proceedings of the National Academy of Sciences) July 21, 2015 vol. 112 no. 29 doi: 10.1073/pnas.1502870112

This paper is behind a paywall.

There is a lot of research on applications for nanocellulose, everywhere it seems, except Canada, which at one time was a leader in the business of producing cellulose nanocrystals (CNC).

Here’s a sampling of some of my most recent posts on nanocellulose,

Nanocellulose as a biosensor (July 28, 2015)

Microscopy, Paper and Fibre Research Institute (Norway), and nanocellulose (July 8, 2015)

Nanocellulose markets report released (June 5, 2015; US market research)

New US platform for nanocellulose and occupational health and safety research (June 1, 2015; Note: As you find new applications, you need to concern yourself with occupational health and safety.)

‘Green’, flexible electronics with nanocellulose materials (May 26, 2015; research from China)

Treating municipal wastewater and dirty industry byproducts with nanocellulose-based filters (Dec. 23, 2014; research from Sweden)

Nanocellulose and an intensity of structural colour (June 16, 2014; research about replacing toxic pigments with structural colour from the UK)

I ask again, where are the Canadians? If anybody has an answer, please let me know.

The nanostructure of cellulose at the University of Melbourne (Australia)

This is not the usual kind of nanocellulose story featured here as it doesn’t concern a nanocellulose material. Instead, this research focuses on the structure of cellulose at the nanoscale. From a May 21, 2015 news item on Nanotechnology Now,

Scientists from IBM Research and the Universities of Melbourne and Queensland have moved a step closer to identifying the nanostructure of cellulose — the basic structural component of plant cell walls.

The insights could pave the way for more disease resistant varieties of crops and increase the sustainability of the pulp, paper and fibre industry — one of the main uses of cellulose.

A May 21, 2015 University of Melbourne press release, which originated the news item, describes some of the difficulties of analyzing cellulose at the nanoscale and the role that IBM computer played in overcoming them,

Tapping into IBM’s supercomputing power, researchers have been able to model the structure and dynamics of cellulose at the molecular level.

Dr Monika Doblin, Research Fellow and Deputy Node Leader at the School of BioSciences at the University of Melbourne said cellulose is a vital part of the plant’s structure, but its synthesis is yet to be fully understood.

“It’s difficult to work on cellulose synthesis in vitro because once plant cells are broken open, most of the enzyme activity is lost, so we needed to find other approaches to study how it is made,” Dr Doblin said.

“Thanks to IBM’s expertise in molecular modelling and VLSCI’s computational power, we have been able to create models of the plant wall at the molecular level which will lead to new levels of understanding about the formation of cellulose.”

The work, which was described in a recent scientific paper published in Plant Physiology, represents a significant step towards our understanding of cellulose biosynthesis and how plant cell walls assemble and function.

The research is part of a longer-term program at the Victorian Life Sciences Computation Initiative (VLSCI) to develop a 3D computer-simulated model of the entire plant wall.

Cellulose represents one of the most abundant organic compounds on earth with an estimated 180 billion tonnes produced by plants each year.

A plant makes cellulose by linking simple units of glucose together to form chains, which are then bundled together to form fibres. These fibres then wrap around the cell as the major component of the plant cell wall, providing rigidity, flexibility and defence against internal and external stresses.

Until now, scientists have been challenged with detailing the structure of plant cell walls due to the complexity of the work and the invasive nature of traditional physical methods which often cause damage to the plant cells.

Dr John Wagner, Manager of Computational Sciences, IBM Research – Australia, called it a ‘pioneering project’.

“We are bringing IBM Research’s expertise in computational biology, big data and smarter agriculture to bear in a large-scale, collaborative Australian science project with some of the brightest minds in the field. We are a keen supporter of the Victorian Life Sciences Computation Initiative and we’re very excited to see the scientific impact this work is now having.”

Using the IBM Blue Gene/Q supercomputer at VLSCI, known as Avoca, scientists were able to perform the quadrillions of calculations required to model the motions of cellulose atoms.

The research shows that within the cellulose structure, there are between 18 and 24 chains present within an elementary microfibril, much less than the 36 chains that had previously been assumed.

IBM Researcher, Dr. Daniel Oehme, said plant walls are the first barrier to disease pathogens.

“While we don’t fully understand the molecular pathway of pathogen infection and plant r

You can find out more about this work and affiliated projects at the Australian Research Centre (ARC) of Excellence in Plant Cell Walls.

Italians and Polish collaborate on nanoscale study of vanishing Da Vinci self-portrait

In addition to a new nondamaging technique to examine paintings (my June 2, 2014 post: Damage-free art authentication and spatially offset Raman spectroscopy [SORS]), there’s a new report in a June 3, 2014 news item on ScienceDaily about a nondamaging technique to examine paper such as the paper on which holds a Da Vinci self-portrait,

One of Leonardo da Vinci’s masterpieces, drawn in red chalk on paper during the early 1500s and widely believed to be a self-portrait, is in extremely poor condition. Centuries of exposure to humid storage conditions or a closed environment has led to widespread and localized yellowing and browning of the paper, which is reducing the contrast between the colors of chalk and paper and substantially diminishing the visibility of the drawing.

A group of researchers from Italy and Poland with expertise in paper degradation mechanisms was tasked with determining whether the degradation process has now slowed with appropriate conservation conditions — or if the aging process is continuing at an unacceptable rate.

Caption: This is Leonardo da Vinci's self-portrait as acquired during diagnostic studies carried out at the Central Institute for the Restoration of Archival and Library Heritage in Rome, Italy. Credit: M. C. Misiti/Central Institute for the Restoration of Archival and Library Heritage, Rome

Caption: This is Leonardo da Vinci’s self-portrait as acquired during diagnostic studies carried out at the Central Institute for the Restoration of Archival and Library Heritage in Rome, Italy.
Credit: M. C. Misiti/Central Institute for the Restoration of Archival and Library Heritage, Rome

The June 3, 2014 American Institute of Physics news release on EurekAlert provides more detail about the work,

… the team developed an approach to nondestructively identify and quantify the concentration of light-absorbing molecules known as chromophores in ancient paper, the culprit behind the “yellowing” of the cellulose within ancient documents and works of art.

“During the centuries, the combined actions of light, heat, moisture, metallic and acidic impurities, and pollutant gases modify the white color of ancient paper’s main component: cellulose,” explained Joanna Łojewska, a professor in the Department of Chemistry at Jagiellonian University in Krakow, Poland. “This phenomenon is known as ‘yellowing,’ which causes severe damage and negatively affects the aesthetic enjoyment of ancient art works on paper.”

Chromophores are the key to understanding the visual degradation process because they are among the chemical products developed by oxidation during aging and are, ultimately, behind the “yellowing” within cellulose. Yellowing occurs when “chromophores within cellulose absorb the violet and blue range of visible light and largely scatter the yellow and red portions — resulting in the characteristic yellow-brown hue,” said Olivia Pulci, a professor in the Physics Department at the University of Rome Tor Vergata.

To determine the degradation rate of Leonardo’s self-portrait, the team created a nondestructive approach that centers on identifying and quantifying the concentration of chromophores within paper. It involves using a reflectance spectroscopy setup to obtain optical reflectance spectra of paper samples in the near-infrared, visible, and near-ultraviolet wavelength ranges.

Once reflectance data is gathered, the optical absorption spectrum of cellulose fibers that form the sheet of paper can be calculated using special spectroscopic data analysis.

Then, computational simulations based on quantum mechanics — in particular, Time-Dependent Density Functional Theory, which plays a key role in studying optical properties in theoretical condensed matter physics — are tapped to calculate the optical absorption spectrum of chromophores in cellulose.

“Using our approach, we were able to evaluate the state of degradation of Leonardo da Vinci’s self-portrait and other paper specimens from ancient books dating from the 15th century,” said Adriano Mosca Conte, a researcher at the University of Rome Tor Vergata. “By comparing the results of ancient papers with those of artificially aged samples, we gained significant insights into the environmental conditions in which Leonardo da Vinci’s self-portrait was stored during its lifetime.”

Their work revealed that the type of chromophores present in Leonardo’s self portrait are “similar to those found in ancient and modern paper samples aged in extremely humid conditions or within a closed environment, which agrees with its documented history,” said Mauro Missori, a researcher at the Institute for Complex Systems, CNR, in Rome, Italy.

One of the most significant implications of their work is that the state of degradation of ancient paper can be measured and quantified by evaluation of the concentrations of chromophores in cellulose fibers. “The periodic repetition of our approach is fundamental to establishing the formation rate of chromophores within the self-portrait. Now our approach can serve as a precious tool to preserve and save not only this invaluable work of art, but others as well,” Conte noted.

Absolutely fascinating stuff to those of use who care about yellowing paper. (Having worked in an archives, I care deeply.) Here’s a link to and a citation for the study,

Visual degradation in Leonardo da Vinci’s iconic self-portrait: A nanoscale study by A. Mosca Conte, O. Pulci, M. C. Misiti, J. Lojewska, L. Teodonio1, C. Violante, and M. Missori. Appl. Phys. Lett. 104, 224101 (2014); http://dx.doi.org/10.1063/1.4879838

This is an open access study.

Nonfood to food: transforming cellulose

With concerns about having enough food to feed everyone, the news that researchers from Virginia Tech have found a way to transform cellulose into starch is encouraging. From the Apr. 17, 2013 news item on Azonano,

A team of Virginia Tech researchers has succeeded in transforming cellulose into starch, a process that has the potential to provide a previously untapped nutrient source from plants not traditionally thought of as food crops.

Y.H. Percival Zhang, an associate professor of biological systems engineering in the College of Agriculture and Life Sciences and the College of Engineering, led a team of researchers in the project that could help feed a growing global population that is estimated to swell to 9 billion by 2050. Starch is one of the most important components of the human diet and provides 20-40 percent of our daily caloric intake.

The Apr. 15, 2013 Virginia Tech news release, which originated the news item, describes cellulose and some of the other benefits to be had from transforming it into starch,

Cellulose is the supporting material in plant cell walls and is the most common carbohydrate on earth. This new development opens the door to the potential that food could be created from any plant, reducing the need for crops to be grown on valuable land that requires fertilizers, pesticides, and large amounts of water. The type of starch that Zhang’s team produced is amylose, a linear resistant starch that is not broken down in the digestion process and acts as a good source of dietary fiber. It has been proven to decrease the risk of obesity and diabetes.

This discovery holds promise on many fronts beyond food systems.

“Besides serving as a food source, the starch can be used in the manufacture of edible, clear films for biodegradable food packaging,” Zhang said.  “It can even serve as a high-density hydrogen storage carrier that could solve problems related to hydrogen storage and distribution.”

The news release goes on to provide details about the new process,

“Cellulose and starch have the same chemical formula,” Zhang said. “The difference is in their chemical linkages. Our idea is to use an enzyme cascade to break up the bonds in cellulose, enabling their reconfiguration as starch.”

The new approach takes cellulose from non-food plant material, such as corn stover, converts about 30 percent to amylose, and hydrolyzes the remainder to glucose suitable for ethanol production. Corn stover consists of the stem, leaves, and husk of the corn plant remaining after ears of corn are harvested. However, the process works with cellulose from any plant.

This bioprocess called “simultaneous enzymatic biotransformation and microbial fermentation” is easy to scale up for commercial production. It is environmentally friendly because it does not require expensive equipment, heat, or chemical reagents, and does not generate any waste. The key enzymes immobilized on the magnetic nanoparticles can easily be recycled using a magnetic force.

Zhang designed the experiments and conceived the cellulose-to-starch concept. Zhang and Virginia Tech visiting scholar Hongge Chen are the inventors of the cellulose-to-starch biotransformation, which is covered under a provisional patent application. [emphasis mine] Chun You, a postdoctoral researcher from China at Virginia Tech, and Chen conducted most of the research work.

I think we’re still a long way from being able to munch on corn stalks instead of corn. Also, it’s with some interest I note the researchers’ patent application. Exactly what are they trying to patent?