Tag Archives: chitosan

Cellulose- and chitin-based biomaterial to replace plastics?

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.

Prawn (shrimp) shopping bags and saving the earth

Using a material (shrimp shells) that is disposed of as waste to create a biodegradable product (shopping bags) can only be described as a major win. A Jan. 10, 2017 news item on Nanowerk makes the announcement,

Bioengineers at The University of Nottingham are trialling how to use shrimp shells to make biodegradable shopping bags, as a ‘green’ alternative to oil-based plastic, and as a new food packaging material to extend product shelf life.

The new material for these affordable ‘eco-friendly’ bags is being optimised for Egyptian conditions, as effective waste management is one of the country’s biggest challenges.

An expert in testing the properties of materials, Dr Nicola Everitt from the Faculty of Engineering at Nottingham, is leading the research together with academics at Nile University in Egypt.

“Non-degradable plastic packaging is causing environmental and public health problems in Egypt, including contamination of water supplies which particularly affects living conditions of the poor,” explains Dr Everitt.

Natural biopolymer products made from plant materials are a ‘green’ alternative growing in popularity, but with competition for land with food crops, it is not a viable solution in Egypt.

A Jan. 10, 2017 University of Nottingham press release, which originated the news item,expands on the theme,

This new project aims to turn shrimp shells, which are a part of the country’s waste problem into part of the solution.

Dr Everitt said: “Use of a degradable biopolymer made of prawn shells for carrier bags would lead to lower carbon emissions and reduce food and packaging waste accumulating in the streets or at illegal dump sites. It could also make exports more acceptable to a foreign market within a 10-15-year time frame. All priorities at a national level in Egypt.”

Degradable nanocomposite material

The research is being undertaken to produce an innovative biopolymer nanocomposite material which is degradable, affordable and suitable for shopping bags and food packaging.

Chitosan is a man-made polymer derived from the organic compound chitin, which is extracted from shrimp shells, first using acid (to remove the calcium carbonate “backbone” of the crustacean shell) and then alkali (to produce the long molecular chains which make up the biopolymer).

The dried chitosan flakes can then be dissolved into solution and polymer film made by conventional processing techniques.

Chitosan was chosen because it is a promising biodegradable polymer already used in pharmaceutical packaging due to its antimicrobial, antibacterial and biocompatible properties. The second strand of the project is to develop an active polymer film that absorbs oxygen.

Enhancing food shelf life and cutting food waste

This future generation food packaging could have the ability to enhance food shelf life with high efficiency and low energy consumption, making a positive impact on food wastage in many countries.

If successful, Dr Everitt plans to approach UK packaging manufacturers with the product.

Additionally, the research aims to identify a production route by which these degradable biopolymer materials for shopping bags and food packaging could be manufactured.

I also found the funding for this project to be of interest (from the press release),

The project is sponsored by the Newton Fund and the Newton-Mosharafa Fund grant and is one of 13 Newton-funded collaborations for The University of Nottingham.

The collaborations, which are designed to tackle community issues through science and innovation, with links formed with countries such as Brazil, Egypt, Philippines and Indonesia.

Since the Newton Fund was established in 2014, the University has been awarded a total of £4.5m in funding. It also boasts the highest number of institutional-led collaborations.

Professor Nick Miles Pro-Vice-Chancellor for Global Engagement said: “The University of Nottingham has a long and established record in global collaboration and research.

The Newton Fund plays to these strengths and enables us to work with institutions around the world to solve some of the most pressing issues facing communities.”

From a total of 68 universities, The University of Nottingham has emerged as the top awardee of British Council Newton Fund Institutional Links grants (13) and is joint top awardee from a total of 160 institutions competing for British Council Newton Fund Researcher Links Workshop awards (6).

Professor Miles added: “This is testament to the incredible research taking place across the University – both here in the UK and in the campuses in Malaysia and China – and underlines the strength of our research partnerships around the world.”

That’s it!

Combining chitosan, agarose, and protein gelatine with clay nanotubes to create scaffolds for tissue engineering

Russian scientists have published work on clay nanotube-bipolymer composite scaffolds according to an April 29, 2016 news item on ScienceDaily,

Scientists combined three biopolymers, chitosan and agarose (polysaccharides), and a protein gelatine, as the materials to produce tissue engineering scaffolds and demonstrated the enhancement of mechanical strength (doubled pick load), higher water uptake and thermal properties in chitosan-gelatine-agarose hydrogels doped with halloysite [a clay mineral and a naturally occurring nanotube].

An April 29, 2016 Kazan Federal University (Russia) press release on EurekAlert, which originated the news item, provides more detail and context,

The fabrication of a prototype tissue having functional properties close to the natural ones is crucial for effective transplantation. Tissue engineering scaffolds are typically used as supports which allow cells to form tissue-like structures essentially required for the correct functioning of the cells under the conditions close to the three-dimensional tissue.

Chitosan, a natural biodegradable and chemically versatile biopolymer, has been effectively used in antibacterial, antifungal, anti-tumour and immunostimulating formulations. To overcome the disadvantages of pure chitosan scaffolds such as mechanical fragility and low biological resistance, chitosan scaffolds are typically doped with other supporting compounds which allow for mechanical strengthening, thus yielding ?omposite biologically resistant scaffolds.

Agarose is a galactose-based backbone polysaccharide isolated from red algae, having remarkable mechanical properties which are useful in the design of tissue engineering scaffolds.

Gelatine is formed from collagen by hydrolysis (breaking the triple-helix structure into single-strand molecules) and has a number of advantages over its precursor. It is less immunogenic compared with collagen and it retains informational signal sequences promoting cell adhesion, migration, differentiation and proliferation.

The surface irregularities of the scaffold pores due to the insoluble nanosized components promote the best adhesion of the cells on scaffold materials, while the nanoparticle fillers increase the composites’ strength. Thus, researchers doped halloysite nanotubes into a chitosan-agarose-gelatine matrix to design the implantable 3D cell scaffolds.

The resulting scaffolds demonstrate the shape memory upon deformation and have the porous structure suitable for cell adhesion and proliferation which is essential for artificial tissue fabrication. Macroscopic observations have confirmed that all the samples of scaffolds exhibited the sponge-like behaviour with the shape memory and shape reconstitution after deformation both in wet and dry states.

The swelling experiments indicated that the addition of halloysite can greatly improve the hydrophilicity and wetting of composite scaffolds. The incorporation of halloysite nanotubes into the scaffolds increases the water uptake and subsequently improves the biocompatibility. The intrinsic properties of halloysite nanotubes can be used for further improving the biocompatibility of scaffolds by the loading and sustained release of different bioactive compounds. This opens the prospect for fabrication of scaffolds with defined properties for directed differentiation of cells on matrixes due to gradual release of differentiation factors.

Experiments on two types of human cancer cells (A549 and Hep3B) show that in vitro cell adhesion and proliferation on the nanocomposites occur without changes in viability and cytoskeleton formation.

Further in vivo biocompatibility and biodegradability evaluation in rats has confirmed that the scaffolds promote the formation of novel blood vessels around the implantation sites. The scaffolds show excellent resorption within six weeks after implantation in rats. Neo-vascularization observed in newly formed connective tissue placed near the scaffold allows for the complete restoration of blood flow.

The results obtained indicate that the halloysite doped scaffolds are biocompatible as demonstrated both in vitro and in vivo. In addition, they confirm the great potential of chitosan-agarose-gelatine nanocomposite porous scaffolds doped with halloysite in tissue engineering with potential for sustained nanotube drug delivery.

For anyone interested about drug delivery and nanoparticles, there’s some interesting research profiled in my April 27, 2016 posting which describes how very few nanoparticles are actually delivered to specific sites.

Getting back to the regular program, here’s a link to and a citation for the paper on scaffolds and clay nanotubes,

Clay nanotube–biopolymer composite scaffolds for tissue engineering by Ekaterina A. Naumenko, Ivan D. Guryanov, Raghuvara Yendluri, Yuri M. Lvova, and Rawil F. Fakhrullin. Nanoscale, 2016,8, 7257-7271 DOI: 10.1039/C6NR00641H First published online 01 Mar 2016

This paper is behind a paywall.

Sunscreen based on algae, reef fish mucus, and chitosan

The proposed sunscreen is all natural and would seem to avoid some of the environmental problems associated with other sunscreens (e.g., washing off into the ocean and polluting it). From a July 29, 2015 American Chemical Society (ACS) news release (also on EurekAlert), Note: Links have been removed,

For consumers searching for just the right sunblock this summer, the options can be overwhelming. But scientists are now turning to the natural sunscreen of algae — which is also found in fish slime — to make a novel kind of shield against the sun’s rays that could protect not only people, but also textiles and outdoor materials. …

Existing sunblock lotions typically work by either absorbing ultraviolet rays or physically blocking them. A variety of synthetic and natural compounds can accomplish this. But most commercial options have limited efficiency, pose risks to the environment and human health or are not stable. To address these shortcomings, Vincent Bulone, Susana C. M. Fernandes and colleagues looked to nature for inspiration.

The researchers used algae’s natural sunscreen molecules, which can also be found in reef fish mucus and microorganisms, and combined them with chitosan, a biopolymer from crustacean shells. Testing showed their materials were biocompatible, stood up well in heat and light, and absorbed both ultraviolet A and ultraviolet B radiation with high efficiency.

The authors acknowledge funding from the European Commission Marie Curie Intra-European Fellowship, the KTH Advanced Carbohydrate Materials Consortium (CarboMat), the Swedish Research Council for Environment, Agricultural Sciences and Spatial Planning (FORMAS) and the Basque Government Department of Education.

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

Exploiting Mycosporines as Natural Molecular Sunscreens for the Fabrication of UV-Absorbing Green Material by Susana C. M. Fernandes, Ana Alonso-Varona, Teodoro Palomares, Verónica Zubillaga, Jalel Labidi, and Vincent Bulone.
ACS Appl. Mater. Interfaces, Article ASAP DOI: 10.1021/acsami.5b04064 Publication Date (Web): July 13, 2015
Copyright © 2015 American Chemical Society

This paper is behind a paywall.

NanoStruck, an Ontario (Canada) water remediation and ‘mining’ company

Located in Mississauga, Ontario (Canada), Nanostruck’s Dec. 20, 2013 news release seems to be functioning as an announcement of its presence rather than any specific company developments,

NanoStruck has a suite of technologies that remove molecular sized particles using patented absorptive organic polymers. The company is sitting on some very incredible and environmently friendly technology.

Organic polymers are nature’s very own sponges. These versatile biomaterials are derived from crustacean shells or plant fibers, depending on requirements of their usage. Acting as molecular sponges, the nanometer-sized polymers are custom programmed toabsorb specific particles for remediation or retrieval purposes. These could be to clean out acids, hydrocarbons, pathogens, oils and toxins in water via its NanoPure solutions. Or to recover precious metal particles in mine tailings, such as gold, silver, platinum, palladium and rhodium using the Company’s NanoMet solutions.

By using patented modifications to conventional technologies and adding polymer-based nano-filtration, the Company’s offers environmentally safe NanoPure solutions for water purification. The Company uses Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines as a benchmark for water quality and safety to conform to acceptable agricultural or drinking water standards in jurisdictions where the technology is used. The worldwide shortage of cleanwater is highlighted on sites such as http://water.org/water-crisis/water-facts/water/.

The company’s NanoPure technology was first deployed to treat wastewater from a landfill site in January 2012 in Mexico. It has since been successfully treating and producing clean water there that’s certified by Conagua, the federal water commission of Mexico. The company has also created water treatment plants in Canada 

Additionally, the Company’s technology can be used to recover precious and base metals from mine tailings, which are the residual material from earlier mining activities. By retrieving valuable metals from old tailing dumps, the Company’s NanoMet solutions boosts the value of existing mining assets and reduces the need for new, costly and potentially environmentally harmful exploration and mining. 

There is an estimated $1 trillion worth of precious metals already extracted from the ground sitting in old mining sites that form our target market. We are in the process of deploying precious metal recovery plants in South Africa, Mexico and Canada.

The company is also developing new plant-based organic polymers to remove contaminants specific to the oil industry, such as naphthenic acids, which is a growing problem.

 Company information is available at www.nanostruck.ca and some description of the companies polymers are below

General Description of Nano Filtration Materials

Chitosan is a polysaccharide-based biomaterial derived from renewable feedstock such as the shells of crustaceans.  Chitosan displays limited adsorbent properties toward various types of contaminants (i.e. petrochemicals, pharmaceuticals, & agrochemicals).  By comparison, synthetically engineered biomaterials that utilize chitosan building blocks display remarkable sorption properties that are tunable toward various types of water borne contaminants.  Recent advances in materials science have enabled the development of Nano Filtration media with relative ease, low toxicity, and tunable molecular properties for a wide range of environmental remediation applications.  …

From what I can tell, the company has technology that can be used to remediate water (NanoPure) and, in the case of remediating mine tailings (NanoMet), allows for reclamation of the metals. It’s the kind of technology that can make you feel virtuous (reclaiming water) with the potential of paying you handsomely (reclaiming gold, etc.).

As I like to do from time to time, I followed the link to the water organization listed in the news release and found this on Water.org’s About Us page,

The water and sanitation problem in the developing world is far too big for charity alone. We are driving the water sector for new solutions, new financing models, greater transparency, and real partnerships to create lasting change. Our vision: Safe water and the dignity of a toilet for all, in our lifetime.

Co-founded by Matt Damon and Gary White, Water.org is a nonprofit organization that has transformed hundreds of communities in Africa, South Asia, and Central America by providing access to safe water and sanitation.

Water.org traces its roots back to the founding of WaterPartners International in 1990. In July 2009, WaterPartners merged with H2O Africa, resulting in the launch of Water.org. Water.org works with local partners to deliver innovative solutions for long-term success. Its microfinance-based WaterCredit Initiative is pioneering sustainable giving in the sector.

Getting back to NanoStruck, here’s more from their About page,

NanoStruck Technologies Inc. is a Canadian Company with a suite of technologies that remove molecular sized particles using patented absorptive organic polymers. These versatile biomaterials are derived from crustacean shells or plant fibers, depending on requirements of their usage. Acting as molecular sponges, the nanometer-sized polymers are custom programmed toabsorb specific particles for remediation or retrieval purposes. These could be to clean out acids, hydrocarbons, pathogens, oils and toxins in water via its NanoPure solutions. Or to recover precious metal particles in mine tailings, such as gold, silver, platinum, palladium and rhodium using the Company’s NanoMet solutions.

By using patented modifications to conventional technologies and adding polymer-based nano-filtration, the Company’s offers environmentally safe NanoPure solutions for water purification. The Company uses Environmental Protection Agency (EPA) and World Health Organization (WHO) guidelines as a benchmark for water quality and safety to conform to acceptable agricultural or drinking water standards in jurisdictions where the technology is used.

The Company’s current business model is based on either selling water remediation plants or leasing out units and charging customers on a price per liter basis with a negotiated minimum payment per annum. For processing mine tailings, the value of precious metal recovered is shared with tailing site owners on a pre-agreed basis.

I wonder if there are any research papers about the January 2012 work in Mexico. I find there is a dearth of technical information on the company’s website, which is somewhat unusual for a startup company (my experience is that they give you too much technical information in a fashion that is incomprehensible to anyone other than en expert). As well, I’m not familiar with any members of the company’s management team (Our Team webpage) but, surprisingly, there isn’t a Chief Science Officer or someone on the team from the science community. In fact, the entire team seems to have emerged from the business community. If I have time, I’ll see about getting an interview for publication here in 2014. In the meantime, it looks like a company with some interesting potential and I wish it well.

(Note: This is not endorsement or anti-endorsement of the company or its business. This is not my area of expertise.)

Think shrimp for wound healing and face creams for age-defying skin

A research team at Fairleigh Dickinson University (New Jersey, US) has taken the first step towards developing new treatments for skin wounds and, possibly, new anti-aging cosmetics. From the March 16, 2012 news item on physorg.com,

… Mihaela Leonida of Fairleigh Dickinson University, in Teaneck, New Jersey and colleagues writing in the International Journal of Nano and Biomaterials describe how they have prepared nanoparticles of chitosan that could have potential in preventing infection in wounds as well as enhancing the wound-healing process itself by stimulating skin cell growth.

Here’s where the shrimp figure in,

Chitosan is a natural, non-toxic and biodegradable, polysaccharide readily obtained from chitin, the main component of the shells of shrimp, lobster and the beak of the octopus and squid. Its antimicrobial activity is well known and has been exploited in dentistry to prevent caries and as preservative applications in food packaging. It has even been tested as an additive for antimicrobial textiles used in clothing for healthcare and other workers.

You can also find this March 16, 2012 news item on Nanowerk,

The team made their chitosan nanoparticles (CNP) using an ionic gelation process with sodium tripolyphosphate. This process involves the formation of bonds between polymers strands, a so-called cross-linking process. Conducted in these conditions it precludes the need for complex preparative chemistry or toxic solvents. CNP can also be made in the presence of copper and silver ions, known antimicrobial agents. The researchers’ preliminary tests show the composite materials to have enhanced activity against two representative types of bacteria.

… The team has also demonstrated that the CNP have skin regenerative properties in tests on skin cell fibroblasts and keratinocytes, in the laboratory, which might even have implications for anti-aging skin care products.

Step closer to integrating electronics into the body

The Sept. 20, 2011 news item (Proton-based transistor could let machines communicate with living things) on Nanowerk features a rather interesting development,

Human devices, from light bulbs to iPods, send information using electrons. Human bodies and all other living things, on the other hand, send signals and perform work using ions or protons.

Materials scientists at the University of Washington have built a novel transistor that uses protons, creating a key piece for devices that can communicate directly with living things.

Here’s a diagram from the University of Washington Sept. 20, 2011 article about the proton transistor by Hannah Hickey,

 

On the left is a colored photo of the UW device overlaid on a graphic of the other components. On the right is a magnified image of the chitosan fibers. The white scale bar is 200 nanometers. (Marco Rolandi, UW)

Here’s a little more about the proton transistor (from the Hickey article),

In the body, protons activate “on” and “off” switches and are key players in biological energy transfer. Ions open and close channels in the cell membrane to pump things in and out of the cell. Animals including humans use ions to flex their muscles and transmit brain signals. A machine that was compatible with a living system in this way could, in the short term, monitor such processes. Someday it could generate proton currents to control certain functions directly.

A first step toward this type of control is a transistor that can send pulses of proton current. The prototype device is a field-effect transistor, a basic type of transistor that includes a gate, a drain and a source terminal for the current. The UW prototype is the first such device to use protons. It measures about 5 microns wide, roughly a twentieth the width of a human hair.

As for the device (from the Hickey article),

The device uses a modified form of the compound chitosan originally extracted from squid pen, a structure that survives from when squids had shells. The material is compatible with living things, is easily manufactured, and can be recycled from crab shells and squid pen discarded by the food industry.

There is a minor Canadian connection,

Computer models of charge transport developed by co-authors M.P. Anantram, a UW professor of electrical engineering, and Anita Fadavi Roudsari at Canada’s University of Waterloo, were a good match for the experimental results.

If I understand this correctly, the computer models were confirmed by the experimental  results, which means the computer models can be used (to augment the use of expensive experiments) with a fair degree of confidence.

I am finding this integration of electronics into the body both fascinating and disturbing as per my paper, Whose electric brain? More about that when I have more time.