Tag Archives: US Dept. of Agriculture

Cotton and nanotechnology at the US Dept. of Agriculture

The April 2012 item by Jan Suszkiw of the US Dept. of Agriculture (on the Western Farm Press website) seemed strangely familiar as it focused on research into flame-retardant cotton. From the Suszkiw article,

In one ongoing project, the researchers have teamed with Texas A&M University scientists to evaluate a first-of-its-kind, environmentally friendly flame-retardant for cotton apparel and durable goods. Halogenated flame retardants have been among the most widely used chemical treatments, but there’s been a push to find alternatives that are more benign and that won’t cause treated fabric to stiffen, according to Condon [Brian Condon, Agricultural Research Service [ARS]).

I mentioned the research work in the context of a 2011 meeting of the American Chemical Society in my Sept. 6, 2011 posting (scroll down about 3/4 of the way) except the focus was on the Texas A&M University in College Station research team who had yet to collaborate with Condon’s team at the ARS,

In responding to the need for more environmentally friendly flame retardants, Grunlan’s [Jaime C. Grunlan] team turned to a technology termed “intumescence,” long used to fireproof exposed interior steel beams in buildings. At the first lick of a flame, an intumescent coating swells up and expands like beer foam, forming tiny bubbles in a protective barrier that insulates and shields the material below. The researchers are at Texas A&M University in College Station. …

Since the meeting last fall, the two teams (US ARS [Condon] and Texas A&M [Grunlan]) have collaborated to make cotton more flame retardant according to the April 2012 news article (Cotton Gets Nanotech and Biotech Treatment in New Orleans) on the US Dept. of Agriculture, Agricultural Research Service website (Note: I have removed a link),

Condon and CCUR (Cotton Chemistry and Utilization Research Unit) chemist SeChin Chang are collaborating with Texas A&M University (TAMU) scientists to evaluate a first-of-its-kind, environmentally friendly flame retardant for cotton apparel and durable goods.

Halogenated flame retardants have been among the most widely used chemical treatments for cotton. But there’s been a push to find alternatives that are not only more benign, but that also avoid imparting the same stiffness to fabric characteristic of some chemical treatments. For these and other reasons, “the textiles industry would like to move away from using halogenated flame retardants,” says Condon.

Made of water-soluble polymers, nanoscale clay particles, and other “green” ingredients, the ARS-TAMU flame retardant is applied as a nanocoating that reacts to open flame by rapidly forming a swollen, charred surface layer. This process, known as “intumescence,” stops the flame from reaching underlying or adjacent fibers.

A team led by Jaime Grunlan at TAMU’s Department of Mechanical Engineering, in College Station, Texas, originally developed the intumescent nanocoating using a layer-by-layer assembly. In this procedure, alternating layers of positively and negatively charged ingredients, including clay particles 50-100 nanometers wide, are deposited onto the surface of a desired material. The result is a striated nanocoating that, when viewed under a scanning electron or other high-powered microscope, resembles the stacked layers of a brick wall.

Condon’s interest was piqued after listening to Grunlan discuss his team’s research at a recent American Chemical Society meeting, and he approached the TAMU professor about potential benefits to cotton. That conversation, in turn, led to a cooperative research project enabling Condon and Chang to evaluate the nanocoating at CCUR.

Treating cotton for flame resistance isn’t a recent concept, adds Condon, whose lab is part of the ARS Southern Regional Research Center in New Orleans. In fact, some of the most successful early treatments were born of research conducted by Benerito [Ruth Benerito] and colleagues there several decades ago. (See “Cross-Linking Cotton,” Agricultural Research, February 2009, pp. 10-11.) Condon coauthored a 2011 ACS Nano paper on the potential of intumescent coatings together with Chang, Grunlan and his TAMU team, and Alexander Morgan of the University of Dayton Research Institute in Ohio.

Early trials of the nanocoating using standard flame-resistance tests are promising. In one case, 95 percent of treated cotton fabric remained intact after exposure to flame, whereas the untreated fabric used for comparison was completely destroyed

“What we’re investigating now is how well it will perform after repeated launderings of treated fabric,” says Condon. “After all, the coating contains clay, and that’s something detergents are made to remove.”

Even if the coating does eventually wash out and the treated fabric loses its flame resistance, the nanotech approach could still be used to protect textiles and durable goods that aren’t frequently washed, such as upholstery, mattress pads, box spring covers, automotive interiors, and firefighter coats.

This is one of the images that accompany the article,

Cross-section of a cotton fiber with clay nanoparticles attached. (from: http://www.ars.usda.gov/is/AR/archive/apr12/cotton0412.htm)

If you are interested in the work being done by the US Dept. of Agriculture’s Agricultural Research Service on cotton, there’s a lot more than I managed to excerpt.

Nanocellulose at the American Chemical Society’s 243rd annual meeting

Nanocellulose seems to be one of the major topics at the ACS’s (Americal Chemical Society) 243rd annual meeting themed Chemistry of Life  in San Diego, California, March 25-29, 2012. From the March 25, 2012 news item on Nanowerk,

… almost two dozen reports in the symposium titled, “Cellulose-Based Biomimetic and Biomedical Materials,” that focused on the use of specially processed cellulose in the design and engineering of materials modeled after biological systems. Cellulose consists of long chains of the sugar glucose linked together into a polymer, a natural plastic–like material. Cellulose gives wood its remarkable strength and is the main component of plant stems, leaves and roots. Traditionally, cellulose’s main commercial uses have been in producing paper and textiles –– cotton being a pure form of cellulose. But development of a highly processed form of cellulose, termed nanocellulose, has expanded those applications and sparked intense scientific research. Nanocellulose consists of the fibrils of nanoscale diameters so small that 50,000 would fit across the width of the period at the end of this sentence.

“We are in the middle of a Golden Age, in which a clearer understanding of the forms and functions of cellulose architectures in biological systems is promoting the evolution of advanced materials,” said Harry Brumer, Ph.D., of Michael Smith Laboratories, University of British Columbia, Vancouver. He was a co-organizer of the symposium with J. Vincent Edwards, Ph.D., a research chemist with the Agricultural Research Service, U.S. Department of Agriculture in New Orleans, Louisiana. “This session on cellulose-based biomimetic and biomedical materials is really very timely due to the sustained and growing interest in the use of cellulose, particularly nanoscale cellulose, in biomaterials.”

One of the presenters has a very charming way of describing the nanocellulose product his team is working on (from the news item),

Olli Ikkala, Ph.D., [Aalto University, Finland] described the new buoyant material, engineered to mimic the water strider’s long, thin feet and made from an “aerogel” composed of the tiny nano-fibrils from the cellulose in plants. Aerogels are so light that some of them are denoted as “solid smoke. [emphasis mine]” The nanocellulose aerogels also have remarkable mechanical properties and are flexible.

There were some 20 presentations in this symposium held under the auspices of the ACS annual meeting. Here’s a few of the presentations (some of these folks have been featured on this blog previously), from the news item,

Native cellulose nanofibers: From biomimetic nanocomposites to functionalized gel spun fibers and functional aerogels Olli Ikkala, Professor, PhD, Aalto University, P.O. Box 5100, Espoo, Finland, FIN-02015, Finland , 358-9-470 23154, olli.ikkala@aalto.fi Native cellulose nanofibers and whiskers attract interest even beyond the traditional cellulose community due to their mechanical properties, availability and sustainability. We describe biomimetic nanocomposites with aligned self-assemblies combining nanocellulose with nanoclays, polymers, block copolymer, or graphene, allowing exciting mechanical properties. Functional ductile and even flexible aerogels are presented, combining superhydrophobicity, superoleophobicity, oil-spill absorption, photocatalytics, optically switchable water absorption, sensing, and antimicrobial properties. Finally mechanically excellent fibers are gel-spun and functionalized for electric, magnetic, optical and drug-release properties.

Evaluation of skin tissue repair materials from bacterial cellulose Lina Fu, Miss, Huazhong University of Science & Technology, College of Life Science & Technology, 1037 Luoyu Road, Wuhan, Hubei, 430074, China , 86-18971560696, runa0325@gmail.com Bacterial cellulose (BC) has been reported as the materials in the tissue engineering fields, such as skin, bone, vascular and cartilage tissue engineering. Exploitation of the skin substitutes and modern wound dressing materials by using BC has attracted much attention. A skin tissue repair materials based on BC have been biosynthesized by Gluconacetobacter xylinus. The nano-composites of BC and chitosan form a cohesive gel structure, and the cell toxicity of the composite is excellent. Unlike other groups, which showed more inflammatory behavior, the inflammatory cells of the BC group were mainly polymorph-nuclear and showed few lymphocytes. The BC skin tissue repair material has an obviously curative effect in promoting the healing of epithelial tissue and reducing inflammation. With its superior mechanical properties, and the excellent biocompatibility, these skin tissue repair materials based on BC have great promise and potential for wound healing and very high clinical value.

….

New materials from nanocrystalline cellulose Mark MacLachlan [mentioned in my Nov. 18, 2010 posting], University of British Columbia, Department of Chemistry, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada , 604-822-3070, mmaclach@chem.ubc.ca Nanocrystalline cellulose (NCC) is available from the acid-catalyzed degradation of cellulosic materials. NCC is composed of cylindrical crystallites with diameters of ca. 5-10 nm and large aspect ratios. This form of cellulose has intriguing properties, including its ability to form a chiral nematic structure. By using the chiral nematic organization of NCC as a template, we have been able to create highly porous silica films and carbon films with chiral nematic organization.1,2 These materials are iridescent and their structures mimic the shells of jewel beetles. In this paper, I will describe our recent efforts to use NCC to create new materials with interesting optical properties.

Factors influencing chiral nematic pitch and texture of cellulose nanocrystal films Derek G Gray, McGill University, Department of Chemistry, Pulp and Paper Building, 3420 University Street, Montreal, QC, H3A 2A7, Canada , 1-514-398-6182, derek.gray@mcgill.ca Appropriately stabilized cellulose nanocrystal (NCC) suspensions in water form chiral nematic liquid crystalline phases above some critical concentration. In the absence of added electrolye, the chiral nematic pitch of such suspensions is longer than that of visible light. Films prepared by evaporation from the suspensions also often display the characteristic fingerprint patterns characteristic of long-pitch chiral nematic phases, but the pitch values can be shifted into the visible range by adding small quantities of electrolyte to the evaporating suspension. The factors that control the final pitch have been the subject of some confusion. While still not well understood, it is clear that at high nanocrystal concentrations and in solid films, the pitch is not simply a reversible function of nanocrystal concentration. We examine some of the factors that control the pitch and liquid crystal texture during the drying of chiral nematic NCC films.

….

Bioprinting of 3D porous nanocellulose scaffolds for tissue engineering and organ regeneration Paul Gatenholm, Professor, [mentioned in my March 19, 2012 posting] Wallenberg Wood Science Center, Chalmers, Department of Chemical and Biological Engineering, Kemigarden 4, Goteborg, V. Gotaland, SE41296, Sweden , 46317723407, paul.gatenholm@chalmers.se Nanocellulose is a promising biocompatible hydrogel like nano-biomaterial with potential uses in tissue engineering and regenerative medicine. Biomaterial scaffolds for tissue engineering require precise control of porosity, pore size, and pore interconnectivity. Control of scaffold architecture is crucial to promote cell migration, cell attachment, cell proliferation and cell differentiation. 3D macroporous nanocellulose scaffolds, produced by unique biofabrication process using porogens incorporated in the cultivation step, have shown ability to attract smooth muscle cells, endothelial cells, chondrocytes of various origins, urethral cells and osteoprogenitor cells. We have developed bioprinter which is able to produce 3D porous nanocellulose scaffolds with large size and unique architecture. Surface modifications have been applied to enhance cell adhesion and cell differentiation. In this study we have focused on use of 3D porous Nanocellulose scaffolds for stem cell differentiation into osteogenic and chondral lineages.

Nano, the Memphis Zoo, and connecting with kids

Who would have thought that the US Dept. of Agriculture would be awarding the Memphis Zoo $500,000.00 for a project to connect rural schools online for a NanoZoo? Kudos to Dr. Helen Beady, Director of Education, and the staff at the Memphis Zoo for a truly imaginative approach to science education.  From the March 9, 2011 news release,

Dr. Helen Beady, Memphis Zoo Director of Education, applied for this grant [Distance Learning and Telemedicine Grant Program] to help fund the Education Department’s ventures in nanotechnology through a program called “NanoZoo Connects.” This program will initially reach 14 schools in rural Tennessee through distance learning technology.

The Memphis Zoo’s “Discovery Center” will be renovated to become a state-of-the-art studio in which Zoo educators will be able to communicate through a video-bridge with some 7000 students in rural classrooms.

“This is just the beginning,” said Dr. Beady. “This grant will give us the ability to begin a program that will be improved and expanded for years to come. We can’t wait to see what the future holds for distance learning through this new technology.”

It was a story about a lotus leaf at a conference presentation that fired Helen Beady’s imagination three years ago. Scientists working at the nanoscale talk a lot about biomimcry. The lotus leaf is an excellent example of a material that is naturally water-resistant and finding out how the leaf achieves its water-resistant state and using that knowledge to create new textiles is an example of biomimicry.

The notion of biomimicry that helped Dr. Beady to tie together her interest in nanotechnology with exciting children’s interest in the zoo and the animals and integrating STEM (science, technology, engineering, and mathematics) education objectives in a single programme,  NanoZoo.  That project designed for students from kindergarten to high school was launched in August 2010. From the news release,

The concept of nanotechnology as it is taught through “NanoZoo” explores the ways animals and plants can help science improve the way we live and work. For example, students are taught how the Lotus leaf has inspired the development of fabrics that can remain under water for days and not get wet, and how the stick-ability of a Gecko’s foot has motivated the production of tape that allows a robot to walk vertically up a wall.

This new project which is being funded through the Dept. of Agriculture is the NanoZoo Connects distance education project.  From the news release,

“NanoZoo and distance learning bring the Memphis Zoo on the cutting edge of technology,” said Zoo President and CEO, Chuck Brady. “What we learn in the early stages of these initiatives will revolutionize the way we are able to help educate students in Tennessee and, one day, across the globe.

The $500,000. will purchase equipment necessary to make the distance education experience successful. (If you’ve ever struggled with connections and bug-ridden software while trying to pursuing any kind of distance education programme, you can appreciate how important good equipment and software are.) From the news release,

The Memphis Zoo’s “Discovery Center” will be renovated to become a state-of-the-art studio in which Zoo educators will be able to communicate through a video-bridge with some 7000 students in rural classrooms.

What’s striking in this project is the multidisciplinary approach from inception to execution with all of it grounded in the zoo’s basic mission statement: “The Memphis Zoo preserves wildlife through education, conservation and research.” I’ll restate this to say, it’s about discovering and healing the relationship between people, animals, and nature. So by that token, teaching and discussing biomimicry and nanotechnology are not such a far reach as some may believe.

Here’s one last item to illustrate the point. I asked Tiffany Langston, a member of the Memphis Zoo’s marketing and communications department, for something either she or the children have found particularly interesting in the NanoZoo.  Tiffany informed me that the Memphis Zoo is one of only four in the US that have pandas and the only food they will eat is bamboo (40 lbs. per day!). Students at the NanoZoo find out that the fibre within the bamboo stalks features a hexagonal structure at the nanoscale which makes the fibre (at the nanoscale) stronger than steel. Today, scientists are trying to mimic those structures to create strong materials that are produced in a more environmentally friendly fashion than steel.

Meanwhile, Dr. Beady has more projects up her sleeve (from the news release),

The Zoo’s Education Department has recently received a $25,000 environmental grant from the City of Memphis Office of Youth Services and Community Affairs to develop a Science, Technology, Engineering and Math (STEM) field program that focuses on the emerging science nanotechnology. This program will help inner city students draw connections between technology, plants, animals and those things that exist in the “big” world through our “NanoZoo.”

The NanoZoo initiative was celebrated at the Memphis Zoo’s Nano Days event on March 28, 2011 (from the news release),

On March 28, 2011 from 9:00 a.m. until 1:00 p.m. the Memphis Zoo invites you to join us for NanoDays and our One Bazillion Nano Meter Walk (leisurely 1 mile stroll). This event will include hands-on demonstrations which explore how scientists mimic traits of plants and animals to inspire innovations in technology and engineering.

The event attracted US Senator Steve Cohen who had this to say in a recent news release to the Memphis Business Journal (http://www.bizjournals.com/memphis/news/2011/03/28/memphis-zoo-gets-500000-nano-grant.html),

The initiative, NanoZoo Connects!, will help demonstrate how scientists use nanotechnology to mimic particular traits of animals and plants to solve engineering and technological problems, according to a release issued by U.S. Sen. Steve Cohen’s office.

“If we are going to successfully compete in a rapidly changing 21st century global economy, our children must have the necessary tools to get ahead,” Cohen said. “The NanoZoo Connects! program will help us accomplish such a goal.”

Dr. Helen Beady told me that she drew on her experience as a former business owner, where she was in the position of trying to hire people who didn’t have the necessary skills or education, to develop the NanoZoo programme. Multidisciplinary in nature. Dr. Beady has hired an engineer and a PhD. in biochemistry to assist with further developing the NanoZoo.

All of this may or may not lead to ‘successful competition in the 21st century global economy’ but it certainly will lead to children learning more about animals and nature and how we might all better co-exist on this planet.