Category Archives: food

Increased food security with hexanal for younger looking, fresher tasting fruits and vegetables

Also known as an anti-aging agent for your fruit and vegetables, hexanal is an environmentally friendly chemical, which is found naturally. Research has led to a synthesized nanotechnology-enabled product now being commercialized. I’ve been following the story off and on since 2012 (see my ‘India, Sri Lanka, and Canada team up for nanotechnology-enabled food packaging‘ posting). I last wrote about the project in a December 29, 2015 posting.

For some reason, hexanal hit the news hard in 2019 having been preceded by some interest in 2018. What follows is an update and a timeline of sorts.

January 2019: More funding

A January 24,2019 essay (also published on the University of Guelph website on January 29, 2019) by Jayasankar Subramanian and Elizabeth Finnis, both are lead researchers on the the project and professors at the University of Guelph (Canada), provides an overview and an update of the hexanal project (Note: Links have been removed) ,

Fruits like mangoes, bananas, papayas and limes are shipped long distances before they get to your table. Many fruits are delicate, and there may be a long period of time that elapses between when the fruit is picked and its arrival in grocery stores and other markets. They’re often picked before they’re truly ripe in order to increase their shelf life.

Even so, globally, up to 40 per cent of all picked fruit can be lost and this represents billions of dollars. But what if we had the technology to delay fruit’s natural degradation process? This is where hexanal can make a difference.

Fruits like mangoes, bananas, papayas and limes are shipped long distances before they get to your table. Many fruits are delicate, and there may be a long period of time that elapses between when the fruit is picked and its arrival in grocery stores and other markets. They’re often picked before they’re truly ripe in order to increase their shelf life.

Even so, globally, up to 40 per cent of all picked fruit can be lost and this represents billions of dollars. But what if we had the technology to delay fruit’s natural degradation process? This is where hexanal can make a difference.

Hexanal is naturally produced by plants to ward off pests; our research at the University of Guelph has found that when it’s applied externally, hexanal can also slow down the aging process.

Like everything else, fruit ages with time. The shrivelling and rot is triggered by the enzyme phospholipase D (PLD), which causes the eventual collapse of the fruit’s membrane. Essentially, fruit membranes are snug, and function like a brick wall of phospholipid bilayers. Phospholipase D breaks the alignment of the bricks, causing the membrane to crumble. Hexanal acts by reducing and slowing the formation of PLD, which in turn slows the collapse of the fruit’s membrane.

In partnership with agricultural and social science researchers in Canada and five other countries, we have tested nine hexanal technologies. These include a spray formulation that gets applied to fruit when they’re still on trees, post-harvest dips, fruit wraps, stickers and sachets embedded with hexanal.

Our findings have implications for consumers, retailers and, more importantly, farmers. For example, when applied as a pre-harvest spray, hexanal can keep fruit on trees longer and keep it fresher after harvest — up to three weeks longer for mangoes.

Hexanal is naturally produced by all plants and is already found as an additive in some food products. Hexanal is also approved by Health Canada as a flavour formula. Our tests of synthesized hexanal sprays, dips and other technologies showed that there were no negative effects on plants, insects or other animals. In addition, hexanal evaporates within 24 hours, which means there’s no residue left on fruit.

Farmers who participated in hexanal testing in Canada and elsewhere were happy with the product both in terms of its effectiveness and bio-safety.

Currently, hexanal for agricultural use is in the two-year regulatory clearance process in Canada and the U.S. Once the process is complete, hexanal formulations are expected to be available for farmer use and can be accessed through companies with a license for production.

Hexanal slows down the ripening and aging process in fresh produce. Author provided

That’s a stunning difference, eh?

Funding

At about the same time as the Conversation essay by Subramanian and Finnis, the University of Guelph published (on the Council of Ontario Universities website) a January 27, 2019 news release announcing new funds for the project,

A University of Guelph research project that has already improved the livelihoods of small-scale Asian farmers will further expand worldwide, thanks to more than $4.2 million in federal support announced Friday afternoon.

The project involves innovative packaging developed in part by Guelph researchers using nanotechnology to improve the shelf life of mangoes, a major fruit crop in much of the world.

Already, the technology has helped to significantly reduce post-harvest losses in Sri Lanka and India. Poor storage meant that farmers routinely lost up to 40 per cent of their crops, worth upwards of $800 million a year. The new technology has also boosted per-acre revenue.

New funding support from the International Development Research Centre (IDRC) and Foreign Affairs, Trade and Development Canada will allow researchers to broaden this successful initiative to Kenya, Tanzania, and Trinidad and Tobago.

Researchers will also look at other fruit — bananas, grapes, papaya, nectarines and berries — and investigate ways to commercialize the technologies.

… it will also be a main pillar of the Guelph-East Africa Initiative, which U of G established to bring together stakeholders to support research and teaching in food, health, water, education, environment and community.

“This confirms our commitment to improve agriculture in East Africa and around the world.” [said John Livernois, interim vice-president {research} ]

The project involves the use of hexanal, a natural plant product that delays fruit ripening and aging. Guelph plant agriculture professor Gopi Paliyath holds an American patent on the discovery of hexanal as a post-harvest agent. It’s also an FDA-approved food additive.

The project also involves Guelph plant agriculture professors Paliyath and Al Sullivan; Loong-tak Lim from Food Science; and Elizabeth Finnis, Sociology and Anthropology. Foreign research partners are based at Tamil Nadu Agricultural University, India; Industrial Technical Institute, Sri Lanka; University of Nairobi, Kenya; Sokoine University of Agriculture, Tanzania; and the University of [the] West Indies, Trinidad and Tobago.

Prior to more funding: a memorandum of understanding

I’m having to guess as the document about the memorandum of understanding (MOU) to commercialize hexanal is not dated but it seems to have been produced in March 2018. (Canada’s International Development Research Centre ([IDRC] has a webpage about the memorandum but no memorandum that I could find.) I stumbled across this account of the event where the MOU was signed,

Ms. Jennifer Daubeny, Consulate General of Canada, delivered the special address narrating the significance of Canadian fundingin developing nanotechnologies to reduce post-harvest losses that enables food security in Asian Countries. Dr. K. Ramasamy, Vice Chancellor, Tamil Nadu Agricultural University [TNAU], Coimbatore presided over the function and highlighted the role of TNAU in knitting nanotechnology research framework and serving as a torch bearer in the country. He emphasized that the GAC-IDRC Project helped more than 60 students and researchers, developed two technologies, filed patents for two inventions, extensive infrastructure development besides helping more than 12,000 fruit growers in the State of Tamil Nadu. Dr. Jayasankar Subramanian, Professor, University of Guelph, Canada, explained the evolution of the project till reached the stage of technology delivery to benefit farmers. Dr. K.S. Subramanian, NABARD Chair Professor, TNAU, Coimbatore, lead Principal Investigator of the Project for India presented nanotechnologies developed to assist in the entire value chain from the farm to fork. Mr. Arun Nagarajan, President, Tamil Nadu Fruit Growers’ Association, explained that the fruit growers are eager to use the technology to improve their farm income. Mr. Terence Park, Managing Director, Smart Harvest Agri, Canada, [emphasis mine] bestowed interest to take forward the technologies to the farm gate and signed MOU with TNAU for the Commercialization of the Hexanal Formulation. Dr. G.J. Janavi,Professor & Head, Department of Nano Science & Technology, TNAU, Coimbatore welcomed the gathering and Dr. C. Sekar, Dean, Imayam Agricultural College,Turaiyur, and Co-PI of the Project proposed a formal vote of thanks.

The Canadian Consul General Ms. Jennifer Daubeny visited all the exhibits and interacted with students, scholars and researchers besides the NGO partner Myrada. She was very impressed with the technologies developed by TNAU in collaboration with University of Guelph, Canada, and looking forward to support research programs in the near future. More than 200 Scientists and Diplomats from Canada, students, scholars, university officials participated in the event.

Products launch by ITI, Colombo

Two of the project’s technology outputs -hexanal incorporated ITI Bio-wax and the Tree Fresh Formulation spray [emphasis mine] were transferred to Hayleys Agriculture Pvt. Ltd., a reputed Agro Service provider in Sri Lanka. The products were launched on 22ndMarch 2018 at the Taj Samudra Hotel, Colombo. The chief guest at the event was the Hon. Susil Premajayantha, Minister of Science Technology and Research (Min. ST&R). The guest of honour was H.E. David McKinnon, High Commissioner for Canada in Sri Lanka. Others present included the Secretary to the Min. ST&R, The Chairman and Director General, ITI, Mr Rizvi Zaheed, Hayleys Agriculture and his team, the Chairman, National Science Foundation, Sri Lanka, representative of the Chairman Sri Lanka Export Development Board, representatives from the Dialog mobile service provider, the Registrar of Pesticides, representing the Dir. Gen., of Agriculture, President of the Lanka Fruit and Vegetable Producers, Processors and Exporters Association, leading large scale mango, papaya and pineapple growers, several export and fruit processing company representatives, senior officials from the ITI, the multi-disciplinary ITI research team and our partner from CEPA. The press was also well represented and a total of 100 persons were present on this occasion. The Managing Director Hayles, the two PIs’ of the project, the High Commissioner for Canada, The Minister and for ST&R and the Secretary to the Ministry addressed the gathering and the new video clip on the project was viewed. The new products were jointly uncovered for display by the Hon. Minister and H.E., the High Commissioner. Samples of the products were distributed to the President of the Lanka Fruit and Vegetable Producers Processors and Exporters Association and to two leading mango growers. The Project team also took this opportunity to run a presentation on the various stages of the project and related activities, display posters on their research findings and to print and distribute the pamphlets on the same as well as on hexanal, the latter as prepared by our partners from the University of Guelph. The launch ended with a time of fellowship providing a useful opportunity for networking.

A YouTube video about the product launch of hexanal-based Bio-wax and the Tree Fresh Formulation spray (I don’t know if those were the permanent names or if they are specific to Sri Lanka and other countries will adopt other names) helped to establish the date for the MOU. You can find the video here.

Judging from the media stories, the team in India has provided most of the leadership for commercializing hexanal.

Commercialization 2019 and beyond

To sum up, after a memorandum of understanding is signed and some prototype products have been unveiled in India in 2018 then, in early 2019, there’s more funding announced by IDRC to expand the number of countries involved and to continue research into efforts to save other types of produce.

Moving things along is an August 15, 2019 news item on Agropages.com,

Two nano formulations would be commercialized by the Directorate of Agri business development of Tamil Nadu Agricultural University (TNAU) soon.  

Fruity fresh is a liquid nano formulation containing hexanal that keeps fruits and vegetables fresh for more days. The pre-harvest spray of Fruity Fresh extends the shelf life of mango for two weeks on trees and another two weeks under storage conditions by employing post-harvest dip methodology, Dr. A. Lakshmanan, Professor and Head, Department of Nano Science and Technology told a meet on “Linking Nano Stakeholders” held at the University.  

Hexanal has also been successfully encapsulated in polymer matrix either as an electro spun fibre matrix (Nano sticker) or nano-pellets that extends shelf life of fruits by 1-2 weeks during storage and transportation, he said.  

This sticker and pellets technology is highly user friendly and can be placed inside the cartons containing fruits during transport for enhancing the freshness.

According to a November 5, 2019 article by Pearly Neo for foodnavigator-asia.com, there is pricing for four products. Nano Sticker and Nano Pellet each will cost $US 0.028 and the spray, Fruity Fresh, will cost $US 4.23 to $US 5.65 for a one liter bottle diluted in 50 liters of water (for use on approximately five trees) and the Fruity Fresh dipping solution at $US 0.0071per kg.

As far as I’m aware none of these products are available in Canada but there is a website for Smart Harvest Agri, Canada although the name used is a little different. First, there’s the Federal Corporation Information listing for Smart Harvest Agritech Limited. You’ll notice there are two directors,

Amanjit Singh Bains
7685 150B Street
Surrey BC V3S 5P1
Canada

Terence Park
Yongsan CJ Nine Park
Seoul
Korea, Republic of

The company’s Smart Harvest website doesn’t list any products but it does discuss something they call “FRESHXtend technology” for fruits and vegetables.

Final comment

I sometimes hear complaints about government funding and what seems to be a lack of follow through with exciting research work being done in Canada. I hope that in the months to come that this story of an international collaboration, which started with three countries and has now expanded to at least six countries and has led to increased food security with an environmentally friendly material and commercialization of research, gets some attention.

From the few sources I’ve been able to find, it seems India and Sri Lanka are leading the commercialization charge while Canada has contributed to an Asian-led project which has now expanded to include Kenya, Tanzania, and Trinidad and Tobago. Bravo t them all!

Quantum dots as pollen labels: tracking pollinators

Caption: This bee was caught after it visited a flower of which the pollen grains were labelled with quantum dots. Under the microscope one can see where the pollen was placed, and actually determine which insects carry the most pollen from which flower. Credit: Corneile Minnaar

Fascinating, yes? Next, the news and, then, the video about the research,

A February 14, 2019 news item on ScienceDaily announces research from South Africa,

A pollination biologist from Stellenbosch University in South Africa is using quantum dots to track the fate of individual pollen grains. This is breaking new ground in a field of research that has been hampered by the lack of a universal method to track pollen for over a century.

A February 13, 2019 Stellenbosh University press release (also on EurekAlert but published February 14, 2019) by Wiida Fourie-Basson, which originated the news item, expands on the theme,

In an article published in the journal Methods in Ecology and Evolution this week, Dr Corneile Minnaar describes this novel method, which will enable pollination biologists to track the whole pollination process from the first visit by a pollinator to its endpoint – either successfully transferred to another flower’s stigma or lost along the way.

Despite over two hundred years of detailed research on pollination, Minnaar says, researchers do not know for sure where most of the microscopically tiny pollen grains actually land up once they leave flowers: “Plants produce massive amounts of pollen, but it looks like more than 90% of it never reaches stigmas. For the tiny fraction of pollen grains that make their way to stigmas, the journey is often unclear–which pollinators transferred the grains and from where?”

Starting in 2015, Minnaar decided to tread where many others have thus far failed, and took up the challenge through his PhD research in the Department of Botany and Zoology at Stellenbosch University (SU).

“Most plant species on earth are reliant on insects for pollination, including more than 30% of the food crops we eat. With insects facing rapid global decline, it is crucial that we understand which insects are important pollinators of different plants–this starts with tracking pollen,” he explains.

He came upon the idea for a pollen-tracking method after reading an article on the use of quantum dots to track cancer cells in rats (https://doi.org/10.1038/nbt994). Quantum dots are semiconductor nanocrystals that are so small, they behave like artificial atoms. When exposed to UV light, they emit extremely bright light in a range of possible colours. In the case of pollen grains, he figured out that quantum dots with “fat-loving” (lipophilic) ligands would theoretically stick to the fatty outer layer of pollen grains, called pollenkitt, and the glowing colours of the quantum dots can then be used to uniquely “label” pollen grains to see where they end up.

The next step was to find a cost-effective way to view the fluorescing pollen grains under a field dissection microscope. At that stage Minnaar was still using a toy pen from a family restaurant with a little UV LED light that he borrowed from one of his professors.
“I decided to design a fluorescence box that can fit under a dissection microscope. And, because I wanted people to use this method, I designed a box that can easily be 3D-printed at a cost of about R5,000, including the required electronic components.” (view video at https://youtu.be/YHs925F13t0

[or you can scroll down to the bottom of this post]

So far, the method and excitation box have proven itself as an easy and relatively inexpensive method to track individual pollen grains: “I’ve done studies where I caught the insects after they have visited the plant with quantum-dot labelled anthers, and you can see where the pollen is placed, and which insects actually carry more or less pollen.”
But the post-labelling part of the work still requires hours and hours of painstaking counting and checking: “I think I’ve probably counted more than a hundred thousand pollen grains these last three years,” he laughs.

As a postdoctoral fellow in the research group of Prof Bruce Anderson in the Department of Botany and Zoology at Stellenbosch University, Minnaar will continue to use the method to investigate the many unanswered questions in this field.

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

Using quantum dots as pollen labels to track the fates of individual pollen grains by Corneile Minnaar and Bruce Anderson. Methods in Ecology and Evolution DOI: https://doi.org/10.1111/2041-210X.13155 First published: 25 January 2019

This paper is behind a paywall.

Here is the video,

Food nanoparticles and their effect on intestinal flora (i.e., your gut microbiome)

This work from Germany is largely speculative. The scientists seem to be interested in exploring how engineered nanoparticles and naturally occurring nanoparticles in food affect your gut. From a January 29, 2019 news item on ScienceDaily,

The intestinal microbiome is not only key for food processing but an accepted codeterminant for various diseases. Researchers led by the University Medical Center of Johannes Gutenberg University Mainz (JGU) identified effects of nanoparticles on intestinal microorganisms. The ultra-small particles adhere to intestinal microorganisms, thereby affecting their life cycle as well as cross talk with the host. One of the researchers’ observations was that nanoparticles’ binding inhibits the infection with Helicobacter pylori, a pathogen implicated in gastric cancer. The findings will stimulate further epidemiological studies and pave the way for the development of potential ‘probiotic’ nanoparticles for food. The discoveries were published in Science of Food.

A January 29, 2019 Johannes Gutenberg University Mainz (JGU) press release (also on EurekAlert), which originated the news item, provides more detail,

Due to their minute size, nanoparticles have unique characteristics and capabilities, such as adhering to microstructures. Nanotechnology is as an important driver of innovation for both consumer industry and medicine. In medicine, the focus is on improving diagnostics and therapeutics, while industry addresses mainly product optimization. Hence, synthetic nanoparticles are already used as additives to improve the characteristics of food. But how can we use nanotechnology more efficiently and safely in food? And are there unknown effects of nanoparticles, which need to be further exploited?

Nutrition strongly influences the diversity and composition of our microbiome. ‘Microbiome’ describes all colonizing microorganisms present in a human being, in particular, all the bacteria in the gut. In other words, your microbiome includes your intestinal flora as well as the microorganisms that colonize your skin, mouth, and nasal cavity.

Scientists and clinicians are interested in microbiomes because of their positive or negative effects on the host. These include modulation of our immune system, metabolism, vascular aging, cerebral functioning, and our hormonal system. The composition of the microbiome seems to play an important role for the development of various disorders, such as cardiovascular diseases, cancer, allergies, obesity, and even mental disorders. “Hence, nutrition and its containing nanoparticulates may affect the microbiome-host balance, finally influencing human health. In order to reduce potential risks and, ideally, promote health, the impact of dietary nanoparticles needs to be understood,” emphasized Professor David J. McClements from the Department of Food Science at the University of Massachusetts in Amherst, USA.

“Prior to our studies, nobody really looked whether and how nano-additives directly influence the gastrointestinal flora,” commented Professor Roland Stauber of the Department of Otolaryngology, Head, and Neck Surgery at the Mainz University Medical Center. “Hence, we studied at a wide range of technical nanoparticles with clearly defined properties in order to mimic what happens to currently used or potential future nanosized food additives. By simulating the journey of particles through the different environments of the digestive tract in the laboratory, we found that the all tested nanomaterials were indeed able to bind to bacteria.” explained Stauber.

The scientists discovered that these binding processes can have different outcomes. On the one hand, nanoparticle-bound microorganisms were less efficiently recognized by the immune system, which may lead to increased inflammatory responses. On the other hand, ‘nano-food’ showed beneficial effects. In cell culture models, silica nanoparticles inhibited the infectivity of Helicobacter pylori, which is considered to be one of the main agents involved in gastric cancer.

‘It was puzzling that we were able to also isolate naturally occurring nanoparticles from food, like beer, which showed similar effects. Nanoparticles in our daily food are not just those added deliberately but can also be generated naturally during preparation. Nanoparticulates are already omnipresent,” concluded Stauber.

The insights of the study will allow to derive strategies for developing and utilizing synthetic or natural nanoparticles to modulate the microbiome as beneficial ingredients in functional foods. “The challenge is to identify nanoparticles that fit the desired purpose, perhaps even as probiotic food supplements in the future. Challenge accepted,” emphasized Stauber and his team.

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

Nanosized food additives impact beneficial and pathogenic bacteria in the human gut: a simulated gastrointestinal study by Svenja Siemer, Angelina Hahlbrock, Cecilia Vallet, David Julian McClements, Jan Balszuweit, Jens Voskuhl, Dominic Docter, Silja Wessler, Shirley K. Knauer, Dana Westmeier, & Roland H. Stauber. npj Science of Foodvolume 2, Article number: 22 (2018) DOI: https://doi.org/10.1038/s41538-018-0030-8 Published 04 December 2018

This paper is open access.

Cellulose and natural nanofibres

Specifically, the researchers are describing these as cellulose nanofibrils. On the left of the image, the seed look mores like an egg waiting to be fried for breakfast but the image on the right is definitely fibrous-looking,

Through contact with water, the seed of Neopallasia pectinata from the family of composite plants forms a slimy sheath. The white cellulose fibres anchor it to the seed surface. Courtesy: Kiel University (CAU)

A December 18, 2018 news item on Nanowerk describes the research into seeds and cellulose,

The seeds of some plants such as basil, watercress or plantain form a mucous envelope as soon as they come into contact with water. This cover consists of cellulose in particular, which is an important structural component of the primary cell wall of green plants, and swelling pectins, plant polysaccharides.

In order to be able to investigate its physical properties, a research team from the Zoological Institute at Kiel University (CAU) used a special drying method, which gently removes the water from the cellulosic mucous sheath. The team discovered that this method can produce extremely strong nanofibres from natural cellulose. In future, they could be especially interesting for applications in biomedicine.

A December 18, 2018 Kiel University press release, which originated the news item, offers further details about the work,

Thanks to their slippery mucous sheath, seeds can slide through the digestive tract of birds undigested. They are excreted unharmed, and can be dispersed in this way. It is presumed that the mucous layer provides protection. “In order to find out more about the function of the mucilage, we first wanted to study the structure and the physical properties of this seed envelope material,” said Zoology Professor Stanislav N. Gorb, head of the “Functional Morphology and Biomechanics” working group at the CAU. In doing so they discovered that its properties depend on the alignment of the fibres that anchor them to the seed surface

Diverse properties: From slippery to sticky

The pectins in the shell of the seeds can absorb a large quantity of water, and thus form a gel-like capsule around the seed in a few minutes. It is anchored firmly to the surface of the seed by fine cellulose fibres with a diameter of just up to 100 nanometres, similar to the microscopic adhesive elements on the surface of highly-adhesive gecko feet. So in a sense, the fibres form the stabilising backbone of the mucous sheath.

The properties of the mucous change, depending on the water concentration. “The mucous actually makes the seeds very slippery. However, if we reduce the water content, it becomes sticky and begins to stick,” said Stanislav Gorb, summarising a result from previous studies together with Dr Agnieszka Kreitschitz. The adhesive strength is also increased by the forces acting between the individual vertically-arranged nanofibres of the seed and the adhesive surface.

Specially dried

In order to be able to investigate the mucous sheath under a scanning electron microscope, the Kiel research team used a particularly gentle method, so-called critical-point drying (CPD). They dehydrated the mucous sheath of various seeds step-by-step with liquid carbon dioxide – instead of the normal method using ethanol. The advantage of this method is that evaporation of liquid carbon dioxide can be controlled under certain pressure and temperature conditions, without surface tension developing within the sheath. As a result, the research team was able to precisely remove water from the mucous, without drying out the surface of the sheath and thereby destroying the original cell structure. Through the highly-precise drying, the structural arrangement of the individual cellulose fibres remained intact.

Almost as strongly-adhesive as carbon nanotubes

The research team tested the dried cellulose fibres regarding their friction and adhesion properties, and compared them with those of synthetically-produced carbon nanotubes. Due to their outstanding properties, such as their tensile strength, electrical conductivity or their friction, these microscopic structures are interesting for numerous industrial applications of the future.

“Our tests showed that the frictional and adhesive forces of the cellulose fibres are almost as strong as with vertically-arranged carbon nanotubes,” said Dr Clemens Schaber, first author of the study. The structural dimensions of the cellulose nanofibers are similar to the vertically aligned carbon nanotubes. Through the special drying method, they can also vary the adhesive strength in a targeted manner. In Gorb’s working group, the zoologist and biomechanic examines the functioning of biological nanofibres, and the potential to imitate them with technical means. “As a natural raw material, cellulose fibres have distinct advantages over carbon nanotubes, whose health effects have not yet been fully investigated,” continued Schaber. Nanocellulose is primarily found in biodegradable polymer composites, which are used in biomedicine, cosmetics or the food industry.

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

Friction-Active Surfaces Based on Free-Standing Anchored Cellulose Nanofibrils by Clemens F. Schaber, Agnieszka Kreitschitz, and Stanislav N. Gorb. ACS Appl. Mater. Interfaces, 2018, 10 (43), pp 37566–37574 DOI: 10.1021/acsami.8b05972 Publication Date (Web): September 19, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Terahertz imagers at your fingertips

It seems to me that I stumbled across quite a few carbon nanotube (CNT) stories in 2018. This one comes courtesy of Japan (from a June 28, 2018 news item on Nanowerk),

Researchers at Tokyo Tech have developed flexible terahertz imagers based on chemically “tunable” carbon nanotube materials. The findings expand the scope of terahertz applications to include wrap-around, wearable technologies as well as large-area photonic devices.

Here’s a peek at an imager,

Figure 1. The CNT-based flexible THz imager (a) Resting on a fingertip, the CNT THz imager can easily wrap around curved surfaces. (b) Just by inserting and rotating a flexible THz imager attached to the fingertip, damage to a pipe was clearly detected. Courtesy Tokyo Tech

A June 28, 2018 Tokyo Tech Institute press release (also on Eurekalert), which originated the news item, provides more detail,

Carbon nanotubes (CNTs) are beginning to take the electronics world by storm, and now their use in terahertz (THz) technologies has taken a big step forward.

Due to their excellent conductivity and unique physical properties, CNTs are an attractive option for next-generation electronic devices. One of the most promising developments is their application in THz devices. Increasingly, THz imagers are emerging as a safe and viable alternative to conventional imaging systems across a wide range of applications, from airport security, food inspection and art authentication to medical and environmental sensing technologies.

The demand for THz detectors that can deliver real-time imaging for a broad range of industrial applications has spurred research into low-cost, flexible THz imaging systems. Yukio Kawano of the Laboratory for Future Interdisciplinary Research of Science and Technology, Tokyo Tech, is a world-renowned expert in this field. In 2016, for example, he announced the development of wearable terahertz technologies based on multiarrayed carbon nanotubes.

Kawano and his team have since been investigating THz detection performance for various types of CNT materials, in recognition of the fact that there is plenty of room for improvement to meet the needs of industrial-scale applications.

Now, they report the development of flexible THz imagers for CNT films that can be fine-tuned to maximize THz detector performance.

Publishing their findings in ACS Applied Nano Materials, the new THz imagers are based on chemically adjustable semiconducting CNT films.

By making use of a technology known as ionic liquid gating1, the researchers demonstrated that they could obtain a high degree of control over key factors related to THz detector performance for a CNT film with a thickness of 30 micrometers. This level of thickness was important to ensure that the imagers would maintain their free-standing shape and flexibility, as shown in Figure 1 [see above].

“Additionally,” the team says, “we developed gate-free Fermi-level2 tuning based on variable-concentration dopant solutions and fabricated a Fermi-level-tuned p-n junction3 CNT THz imager.” In experiments using this new type of imager, the researchers achieved successful visualization of a metal paper clip inside a standard envelope (see Figure 2.)

Non-contact, non-destructive visualization

Figure 2. Non-contact, non-destructive visualization

The CNT THz imager enabled clear, non-destructive visualization of a metal paper clip inside an envelope.

The bendability of the new THz imager and the possibility of even further fine-tuning will expand the range of CNT-based devices that could be developed in the near future.

Moreover, low-cost fabrication methods such as inkjet coating could make large-area THz imaging devices more readily available.

1 Ionic liquid gating

A technique used to modulate a material’s charge carrier properties.

2 Fermi level

A measure of the electrochemical potential for electrons, which is important for determining the electrical and thermal properties of solids. The term is named after the Italian–American physicist Enrico Fermi.

3 p-n junction

Refers to the interface between positive (p-type) and negative (n-type) semiconducting materials. These junctions form the basis of semiconductor electronic devices.

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

Fermi-Level-Controlled Semiconducting-Separated Carbon Nanotube Films for Flexible Terahertz Imagers by Daichi Suzuki, Yuki Ochiai, Yota Nakagawa, Yuki Kuwahara, Takeshi Saito, and Yukio Kawano. ACS Appl. Nano Mater., 2018, 1 (6), pp 2469–2475 DOI: 10.1021/acsanm.8b00421 Publication Date (Web): June 6, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

Genetic engineering: an eggplant in Bangladesh and a synthetic biology grant at Concordia University (Canada)

I have two bits of genetic engineering news.

Eggplants in Bangladesh

I always marvel at their beauty,

Bt eggplant is the first genetically engineered food crop to be successfully introduced in South Asia. The crop is helping some of the world’s poorest farmers feed their families and communities while reducing the use of pesticides. Photo by Cornell Alliance for Science.

A July 17, 2018 news item on phys.org describes a genetic engineering application,

Ansar Ali earned just 11,000 taka – about $130 U.S. dollars – from eggplant he grew last year in Bangladesh. This year, after planting Bt eggplant, he brought home more than double that amount, 27,000 taka. It’s a life-changing improvement for a subsistence farmer like Ali.

Bt eggplant, or brinjal as it’s known in Bangladesh, is the first genetically engineered food crop to be successfully introduced in South Asia. Bt brinjal is helping some of the world’s poorest farmers to feed their families and communities, improve profits and dramatically reduce pesticide use. That’s according to Tony Shelton, Cornell professor of entomology and director of the Bt brinjal project funded by the United States Agency for International Development (USAID). Shelton and Jahangir Hossain, the country coordinator for the project in Bangladesh, lead the Cornell initiative to get these seeds into the hands of the small-scale, resource-poor farmers who grow a crop consumed daily by millions of Bangladeshis.

A July 11, 2018 Cornell University news release by Krisy Gashler, which originated the news item, expands on the theme (Note: Links have been removed),

Bt brinjal was first developed by the Indian seed company Mahyco in the early 2000s. Scientists inserted a gene from the bacterium Bacillus thuringiensis (thus the name, Bt) into nine brinjal varieties. The plants were engineered to resist the fruit and shoot borer, a devastating insect whose larvae bore into the stem and fruit of an eggplant. The insects cause up to 80 percent crop loss.

The Bt protein produced by the engineered eggplant causes the fruit and shoot borer larva to stop feeding, but is safe for humans consuming the eggplant, as proven through years of biosafety trials. In fact, Bt is commonly used by organic farmers to control caterpillars but has to be sprayed frequently to be effective. The Bt eggplant produces essentially the same protein as in the spray. More than 80 percent of field corn and cotton grown in the U.S. contains a Bt gene for insect control.

“Farmers growing Bt brinjal in Bangladesh are seeing three times the production of other brinjal varieties, at half the production cost, and are getting better prices at the market,” Hossain said.

A recent survey found 50 percent of farmers in Bangladesh said that they experienced illness due to the intense spraying of insecticides. Most farmers work in bare feet and without eye protection, leading to pesticide exposure that causes skin and eye irritation, and vomiting.

“It’s terrible for these farmers’ health and the health of the environment to spray so much,” said Shelton, who found that pesticide use on Bt eggplant was reduced as much as 92 percent in commercial Bt brinjal plantings. “Bt brinjal is a solution that’s really making a difference in people’s lives.”

Alhaz Uddin, a farmer in the Tangail district, made 6,000 taka growing traditional brinjal, but had to spend 4,000 taka on pesticides to combat fruit and shoot borer.

“I sprayed pesticides several times in a week,” he said. “I got sick many times during the spray.”

Mahyco initially wanted to introduce Bt brinjal in India and underwent years of successful safety testing. But in 2010, due to pressure from anti-biotechnology groups, the Indian minister of the environment placed a moratorium on the seeds. It is still in effect today, leaving brinjal farmers there without the effective and safe method of control available to their neighbors in Bangladesh.

Even before the Indian moratorium, Cornell scientists hosted delegations from Bangladesh that wanted to learn about Bt brinjal and the Agricultural Biotechnology Support Project II (ABSP II), a consortium of public and private institutions in Asia and Africa intended to help with the commercial development, regulatory approval and dissemination of bio-engineered crops, including Bt brinjal.

Cornell worked with USAID, Mahyco and the Bangladesh Agricultural Research Institute to secure regulatory approval, and in 2014 the Bangladeshi government distributed a small number of Bt brinjal plants to 20 farmers in four districts. The next year 108 farmers grew Bt brinjal, and the following year the number of farmers more than doubled to 250. In 2017 the number increased to 6,512 and in 2018 to 27,012. The numbers are likely even higher, according to Shelton, as there are no constraints against farmers saving seeds and replanting.

“Farmers who plant Bt brinjal are required to plant a small perimeter of traditional brinjal around the Bt variety; research has shown that the insects will infest plants in the buffer area, and this will slow their evolutionary development of resistance to the Bt plants,” Shelton said.

In a March 2017 workshop, Bangladeshi Agriculture Minister Begum Matia Chowdhury called Bt brinjal “a success story of local and foreign collaboration.”

“We will be guided by the science-based information, not by the nonscientific whispering of a section of people,” Chowdhury said. “As human beings, it is our moral obligation that all people in our country should get food and not go to bed on an empty stomach. Biotechnology can play an important role in this effect.”

Here’s what an infested eggplant looks like,

Non-Bt eggplant infested with fruit and shoot borer. Photo by Cornell Alliance for Science

It looks more like a fig than an eggplant.

This is part of a more comprehensive project as revealed in a March 29, 2016 Cornell University news release issued on the occasion of a $4.8M, three-year grant from the U.S. Agency for International Development (USAID),

… The award supports USAID’s work under Feed the Future, the U.S. government’s global initiative to fight hunger and improve food security using agricultural science and technology.

In the Feed the Future South Asia Eggplant Improvement Partnership, Cornell will protect eggplant farmers from yield losses and improve their livelihoods in partnership with the Bangladesh Agricultural Research Institute (BARI) and the University of the Philippines at Los Baños. Eggplant, or brinjal, is a staple crop that is an important source of income and nutrition for farmers and consumers in South Asia.

Over the past decade, Cornell has led the Agricultural Biotechnology Support Project II (ABSPII), also funded by USAID, that prompted a consortium of institutions in Asia and Africa to use the tools of modern biotechnology, particularly genetic engineering, to improve crops to address major production constraints for which conventional plant breeding tools have not been effective.

In October 2013, Bangladesh became the first country in South Asia to approve commercial cultivation of a genetically engineered food crop. In February 2014, Matia Chowdhury, the Bangladesh minister of agriculture, released four varieties of Bt brinjal to 20 farmers. With the establishment of the 20 Bt brinjal demonstration plots in 2014 and 104 more in 2015, BARI reported a noticeable decrease in fruit and shoot borer infestation, increased yields, decreased use of pesticide and improved income for farmers.

The Feed the Future South Asia Eggplant Improvement Partnership addresses and integrates all elements of the commercialization process — including technology development, regulation, marketing, seed distribution, and product stewardship. It also provides strong platforms for policy development, capacity building, gender equality, outreach and communication.

Moving on from practical applications …

Canada’s synthetic biology training centre

It seems Concordia University (Montréa) is a major Canadian centre for all things ‘synthetic biological’. (from the History and Vision webpage on Concordia University’s Centre for Applied Synthetic Biology webspace),

History and vision

Emerging in 2012 from a collaboration between the Biology and Electrical and Computer Engineering Departments, the Centre received University-wide status in 2016 growing its membership to include Biochemistry, Journalism, Communication Studies, Mechanical, Industrial and Chemical Engineering.


Timeline

T17-36393-VPRG-Timeline-graphic-promo-v4

You can see the timeline does not yet include 2018 development(s). Also it started as “a collaboration between the Biology and Electrical and Computer Engineering Departments?” This suggests a vastly different approach to genetic engineering that that employed in the “eggplant” research. From a July 16, 2018 posting on the Genome Alberta blog,

The Natural Sciences and Engineering Research Council of Canada (NSERC) has committed $1.65 million dollars over six years to establish a research and training program at Concordia’s Centre for Applied Synthetic Biology.

The funds were awarded after Malcolm Whiteway (…), professor of biology and the Canada Research Chair in Microbial Genomics, and the grant application team submitted a proposal to NSERC’s Collaborative Research and Training Experience (CREATE) program.

The Synthetic Biology Applications CREATE program — or SynBioApps — will help students acquire and develop important professional skills that complement their academic education and improve their job-readiness.

‘Concordia is a natural fit’

“As the Canadian leader in synthetic biology and as the home of the country’s only genome foundry, Concordia is a natural fit for a training program in this growing area of research,” says Christophe Guy, vice-president of Research and Graduate Studies.

“In offering a program like SynBioApps, we are providing our students with both a fundamental education in science and the business skills they’ll need to transition into their professional careers.”

The program’s aims are twofold: First, it will teach students how to design and construct cells and proteins for the development of new products related to human health, green technologies, and fundamental biological investigations. Second, it will provide cross-disciplinary training and internship opportunities through the university’s District 3 Innovation Center.

SynBioApps will be open to students from biology, biochemistry, engineering, computing, and mathematics.

“The ability to apply engineering approaches to biological systems promises to revolutionize both biology and industry,” says Whiteway, who is also a member of the Centre for Applied Synthetic Biology.

“The SynBioApps program at Concordia will provide a training program to develop the students who will both investigate the biology and build these industries.”

You can find out more about Concordia’s Centre for Applied Synthetic Biology here (there are jobs listed on their home page) and you can find information about the Synthetic Biology Applications (SynBioApps) training programme here.

Do you want that coffee with some graphene on toast?

These scientists are excited:

For those who prefer text, here’s the Rice University Feb. 13, 2018 news release (received via email and available online here and on EurekAlert here) Note: Links have been removed),

Rice University scientists who introduced laser-induced graphene (LIG) have enhanced their technique to produce what may become a new class of edible electronics.

The Rice lab of chemist James Tour, which once turned Girl Scout cookies into graphene, is investigating ways to write graphene patterns onto food and other materials to quickly embed conductive identification tags and sensors into the products themselves.

“This is not ink,” Tour said. “This is taking the material itself and converting it into graphene.”

The process is an extension of the Tour lab’s contention that anything with the proper carbon content can be turned into graphene. In recent years, the lab has developed and expanded upon its method to make graphene foam by using a commercial laser to transform the top layer of an inexpensive polymer film.

The foam consists of microscopic, cross-linked flakes of graphene, the two-dimensional form of carbon. LIG can be written into target materials in patterns and used as a supercapacitor, an electrocatalyst for fuel cells, radio-frequency identification (RFID) antennas and biological sensors, among other potential applications.

The new work reported in the American Chemical Society journal ACS Nano demonstrated that laser-induced graphene can be burned into paper, cardboard, cloth, coal and certain foods, even toast.

“Very often, we don’t see the advantage of something until we make it available,” Tour said. “Perhaps all food will have a tiny RFID tag that gives you information about where it’s been, how long it’s been stored, its country and city of origin and the path it took to get to your table.”

He said LIG tags could also be sensors that detect E. coli or other microorganisms on food. “They could light up and give you a signal that you don’t want to eat this,” Tour said. “All that could be placed not on a separate tag on the food, but on the food itself.”

Multiple laser passes with a defocused beam allowed the researchers to write LIG patterns into cloth, paper, potatoes, coconut shells and cork, as well as toast. (The bread is toasted first to “carbonize” the surface.) The process happens in air at ambient temperatures.

“In some cases, multiple lasing creates a two-step reaction,” Tour said. “First, the laser photothermally converts the target surface into amorphous carbon. Then on subsequent passes of the laser, the selective absorption of infrared light turns the amorphous carbon into LIG. We discovered that the wavelength clearly matters.”

The researchers turned to multiple lasing and defocusing when they discovered that simply turning up the laser’s power didn’t make better graphene on a coconut or other organic materials. But adjusting the process allowed them to make a micro supercapacitor in the shape of a Rice “R” on their twice-lased coconut skin.

Defocusing the laser sped the process for many materials as the wider beam allowed each spot on a target to be lased many times in a single raster scan. That also allowed for fine control over the product, Tour said. Defocusing allowed them to turn previously unsuitable polyetherimide into LIG.

“We also found we could take bread or paper or cloth and add fire retardant to them to promote the formation of amorphous carbon,” said Rice graduate student Yieu Chyan, co-lead author of the paper. “Now we’re able to take all these materials and convert them directly in air without requiring a controlled atmosphere box or more complicated methods.”

The common element of all the targeted materials appears to be lignin, Tour said. An earlier study relied on lignin, a complex organic polymer that forms rigid cell walls, as a carbon precursor to burn LIG in oven-dried wood. Cork, coconut shells and potato skins have even higher lignin content, which made it easier to convert them to graphene.

Tour said flexible, wearable electronics may be an early market for the technique. “This has applications to put conductive traces on clothing, whether you want to heat the clothing or add a sensor or conductive pattern,” he said.

Rice alumnus Ruquan Ye is co-lead author of the study. Co-authors are Rice graduate student Yilun Li and postdoctoral fellow Swatantra Pratap Singh and Professor Christopher Arnusch of Ben-Gurion University of the Negev, Israel. Tour is the T.T. and W.F. Chao Chair in Chemistry as well as a professor of computer science and of materials science and nanoengineering at Rice.

The Air Force Office of Scientific Research supported the research.

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

Laser-Induced Graphene by Multiple Lasing: Toward Electronics on Cloth, Paper, and Food by Yieu Chyan, Ruquan Ye†, Yilun Li, Swatantra Pratap Singh, Christopher J. Arnusch, and James M. Tour. ACS Nano DOI: 10.1021/acsnano.7b08539 Publication Date (Web): February 13, 2018

Copyright © 2018 American Chemical Society

This paper is behind a paywall.

h/t Feb. 13, 2018 news item on Nanowerk

NanoFARM: food, agriculture, and nanoparticles

The research focus for the NanoFARM consortium is on pesticides according to an October 19, 2017 news item on Nanowerk,

The answer to the growing, worldwide food production problem may have a tiny solution—nanoparticles, which are being explored as both fertilizers and fungicides for crops.

NanoFARM – research consortium formed between Carnegie Mellon University [US], the University of Kentucky [US], the University of Vienna [Austria], and Aveiro University in Prague [Czech Republic] – is studying the effects of nanoparticles on agriculture. The four universities received grants from their countries’ respective National Science Foundations to discover how these tiny particles – some just 4 nanometers in diameter – can revolutionize how farmers grow their food.

An October ??, 2017 Carnegie Mellon University news release by Adam Dove, which originated the news item, fills in a few more details,

“What we’re doing is getting a fundamental understanding of nanoparticle-to-plant interactions to enable future applications,” says Civil and Environmental Engineering (CEE) Professor Greg Lowry, the principal investigator for the nanoFARM project. “With pesticides, less than 5% goes into the crop—the rest just goes into the environment and does harmful things. What we’re trying to do is minimize that waste and corresponding environmental damage by doing a better job of targeting the delivery.”

The teams are looking at related questions: How much nanomaterial is needed to help crops when it comes to driving away pests and delivering nutrients, and how much could potentially hurt plants or surrounding ecosystems?

Applied pesticides and fertilizers are vulnerable to washing away—especially if there’s a rainstorm soon after application. But nanoparticles are not so easily washed off, making them extremely efficient for delivering micronutrients like zinc or copper to crops.

“If you put in zinc oxide nanoparticles instead, it might take days or weeks to dissolve, providing a slow, long-term delivery system.”

Gao researches the rate at which nanoparticles dissolve. His most recent finding is that nanoparticles of copper oxide take up to 20-30 days to dissolve in soil, meaning that they can deliver nutrients to plants at a steady rate over that time period.

“In many developing countries, a huge number of people are starving,” says Gao. “This kind of technology can help provide food and save energy.”

But Gao’s research is only one piece of the NanoFARM puzzle. Lowry recently traveled to Australia with Ph.D. student Eleanor Spielman-Sun to explore how differently charged nanoparticles were absorbed into wheat plants.

They learned that negatively charged particles were able to move into the veins of a plant—making them a good fit for a farmer who wanted to apply a fungicide. Neutrally charged particles went into the tissue of the leaves, which would be beneficial for growers who wanted to fortify a food with nutritional value.

Lowry said they are still a long way from signing off on a finished product for all crops—right now they are concentrating on tomato and wheat plants. But with the help of their university partners, they are slowly creating new nano-enabled agrochemicals for more efficient and environmentally friendly agriculture.

For more information, you can find the NanoFARM website here.

Popping (nano)bubbles!

Who doesn’t love to pop bubbles? Well, there’s probably someone out there but it does seem to be a near universal delight (especially with the advent of bubble wrap which I’ve seen more than one person happily popping). Scientists are no more immune to that impulse than the rest of us although they approach the whole endeavour from a more technical perspective where popping bubbles becomes destabilization and bubble rupture. From a Sept. 28, 2017 American Institute of Physics (AIP) news release (also on EurekAlert),

Nanobubbles have recently gained popularity for their unique properties and expansive applications. Their large surface area and high stability in saturated liquids make nanobubbles ideal candidates for food science, medicine and environmental advancements. Nanobubbles also have long lifetimes of hours or days, and greater applicability than traditional macrobubbles, which typically only last for seconds.

The stability of nanobubbles is well understood, but the mechanisms causing their eventual destabilization are still in question. Using molecular dynamics simulations (MDS), researchers from the Beijing University of Chemical Technology explored the effect of surfactants — components that lower surface tension — on the stabilization of nanobubbles. They report their findings on the surprising mechanisms of destabilization [emphasis mine] for both soluble and insoluble surfactants this week [Sept. 25-29, 2017] in Applied Physics Letters, from AIP Publishing.

Researchers investigated the differences between soluble and insoluble surfactants and their varying influence on nanobubble stability using MDS software. They created a controled model system where the only variables that could be manipulated were the number of surfactants and the interaction between the surfactant and the substrate, the base of the model where the bubble is formed, to measure the direct influence of surfactants on nanobubble stability.

Analyzing both soluble and insoluble surfactants, the group focused on two possible mechanisms of destabilization: contact line depinning, where the surfactant flexibility reduces the forces responsible for stabilizing the bubble shape, causing it to rupture from lack of inner surface force; and surface tension reduction, causing a liquid to vapor phase transition.

The found soluble surfactants initiated nanobubble depinning when a large amount, roughly 80 percent, of the surfactant was adsorbed by the substrate, eventually causing the nanobubbles to burst.

“However, when small concentrations of soluble surfactant were introduced it remained dissolved, and adsorption onto the substrate was insignificant, generating a negligible effect on nanobubble stability,” said Xianren Zhang at Beijing University of Chemical Technology.

Simulations with insoluble surfactants showed comparable results to soluble surfactants when interacting heavily with substrates, but a new mechanism was discovered demonstrating a liquid-to-vapor transition model of bubble rupture [emphasis mine].

The transition is similar to how we traditionally envision bubbles popping, occurring when a surfactant significantly reduces the surface tension on the outside of the nanobubble. Nanobubbles destabilize in this fashion when a large amount of surfactant is present, but little — around 40 percent — surfactant-substrate interaction occurs.

These findings are critical to understanding nanobubble stability and have implications for nanobubble interaction with other molecules, including proteins and contaminants. Nanobubble applications could revolutionize aspects of modern medicine such as ultrasound techniques, expand functions in food science, and improve waste water treatment. But better characterizing basic properties like instability is essential to fully utilizing their potential in these applications.

There researchers have made this image illustrating their work available,

Several typical snapshots for nanobubbles losing their stability with various concentrations of surfactants and levels of interaction with substrates. In each picture, top panel shows evolution of the system with all involved particles, while in the bottom panel, solvent molecules are not shown to clarify the effect of surfactants. CREDIT: Qianxiang Xiao, Yawei Liu, Zhenjiang Guo, Zhiping Liu, and Xianren Zhang

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

How nanobubbles lose stability: Effects of surfactants featured by Qianxiang Xiao, Yawei Liu, Zhenjiang Guo, Zhiping Liua, and Xianren Zhang. Appl. Phys. Lett. 111, 131601 (2017); doi: http://dx.doi.org/10.1063/1.5000831

This paper is open access.