Tag Archives: silica

Australians protect grain with diatoms (Nature’s nanofabrication factories)

A Feb. 5, 2014 news item on Nanowerk highlights a presentation about protecting grain from insects given at the  ICONN2014-ACMM23 conference for nanoscience and microscopy held Feb. 3 -6, 2014 at the University of Adelaide (Australia). From the news item,

University of Adelaide researchers are using nanotechnology and the fossils of single-celled algae to develop a novel chemical-free and resistance-free way of protecting stored grain from insects.

The researchers are taking advantage of the unique properties of these single-celled algae, called diatoms. Diatoms have been called Nature’s nanofabrication factories because of their production of tiny (nanoscale) structures made from silica which have a range of properties of potential interest for nanotechnology.

“One area of our research is focussed on transforming this cheap diatom silica, readily available as a by-product of mining, into valuable nanomaterials for diverse applications – one of which is pest control,” says Professor Dusan Losic, ARC Future Fellow in the University’s School of Chemical Engineering.

The Feb. 5, 2014 University of Adelaide media release, which originated the news item, provides more insight into the research,

“There are two looming issues for the world-wide protection against insect pests of stored grain: firstly, the development of resistance by many species to conventional pest controls – insecticides and the fumigant phosphine – and, secondly, the increasing consumer demand for residue-free grain products and food,” Professor Losic says.

“In the case of Australia, we export grain worth about $8 billion each year – about 25 million tonnes – which could be under serious threat. We urgently need to find alternative methods for stored grain protection which are ecologically sound and resistance-free.”

The researchers are using a natural, non-toxic silica material based on the ‘diatomaceous earths’ formed by the fossilisation of diatoms. The material disrupts the insect’s protective cuticle, causing the insect to dehydrate.

“This is a natural and non-toxic material with a significant advantage being that, as only a physical mode of action is involved, the insects won’t develop resistance,” says Professor Losic. [emphasis mine]

“Equally important is that it is environmentally stable with high insecticidal activity for a long period of time. Therefore, stored products can be protected for longer periods of time without the need for frequent re-application.”

PhD student Sheena Chen is presenting her findings on the insecticidal activity of the material. PhD student John Hayles is also working on the project. The research is funded by the Grains Research and Development Corporation. The researchers are in the final stages of optimising the formula of the material.

This work be may of interest to Canadian farmers especially since 2013 featured the largest wheat and canola harvests in Canadian history according to a Dec. 4, 2013 article by Terryn Shiells for AgCanada.com,

“There’s just no getting around it, this is the biggest crop of Canadian history and it’s basically a shocker all around,” said Mike Jubinville of ProFarmer Canada in Winnipeg. “I really can’t think of a crop, other than peas and lentils, that didn’t provide an upside that betters what trade expectations were.”

Because all of the crops are so huge, it won’t be possible to move the entire crop this year, Jubinville said.

“We’re going to argue all we want about rail car allocations, about slow deliverable opportunities, but there’s just no way that the Canadian commercial handling system can move this crop,” he said.

Because there just isn’t enough capacity to get everything moved this year, there will also likely be larger than anticipated carryover stocks of all crops.

I imagine these bumper crops will mean there are storage issues which brings this piece back to the Australians and their work on preserving stored grain by using diatoms and silica material.  Perhaps Canadian farmers would like to test this “new natural and non-toxic material” once the formula has been optimized.

You probably can’t poison yourself by eating too many nanoparticles

Researchers, Ingrid Bergin in the Unit for Laboratory Animal Medicine, at the University of Michigan in Ann Arbor and Frank Witzmann in the Department of Cellular and Integrative Physiology, at Indiana University School of Medicine, in Indianapolis, have stated that ingesting food and beverage (translated by me from the more scientific description) with nanoparticles (at today’s current levels) is unlikely to prove toxic. A June 26, 2013 Inderscience news release on EurekAlert describes the researchers’ research and their conclusions,

Writing in a forthcoming issue of the International Journal of Biomedical Nanoscience and Nanotechnology, researchers have compared existing laboratory and experimental animal studies pertaining to the toxicity of nanoparticles most likely to be intentionally or accidentally ingested. Based on their review, the researchers determined ingestion of nanoparticles at likely exposure levels is unlikely to cause health problems, at least with respect to acute toxicity. Furthermore, in vitro laboratory testing, which often shows toxicity at a cellular level, does not correspond well with in vivo testing, which tends to show less adverse effects.

Ingrid Bergin in the Unit for Laboratory Animal Medicine, at the University of Michigan in Ann Arbor and Frank Witzmann in the Department of Cellular and Integrative Physiology, at Indiana University School of Medicine, in Indianapolis, explain that the use of particles that are in the nano size range (from 1 billionth to 100 billionths of a meter in diameter, 1-100 nm, other thereabouts) are finding applications in consumer products and medicine. These include particles such as nano-silver, which is increasingly used in consumer products and dietary supplements for its purported antimicrobial properties. Nanoparticles can have some intriguing and useful properties because they do not necessarily behave in the same chemical and physical ways as non-nanoparticle versions of the same material.

Nanoparticles are now used as natural flavor enhancers in the form of liposomes and related materials, food pigments and in some so-called “health supplements”. They are also used in antibacterial toothbrushes coated with silver nanoparticles, for instance in food and drink containers and in hygienic infant feeding equipment. They are also used to carry pharmaceuticals to specific disease sites in the body to reduce side effects. Nanoparticles actually encompass a very wide range of materials from pure metals and alloys, to metal oxide nanoparticles, and carbon-based and plastic nanoparticles. Because of their increasing utilization in consumer products, there has been concern over whether these small scale materials could have unique toxicity effects when compared to more traditional versions of the same materials.

Difficulties in assessing the health risks of nanoparticles include the fact that particles of differing materials and shapes can have different properties. Furthermore, the route of exposure (e.g. ingestion vs. inhalation) affects the likelihood of toxicity. The U.S. researchers evaluated the current literature specifically with respect to toxicity of ingested nanoparticles. They point out that, in addition to intentional ingestion as with dietary supplements, unintentional ingestion can occur due to nanoparticle presence in water or as a breakdown product from coated consumer goods. Inhaled nanoparticles also represent an ingestion hazard since they are coughed up, swallowed, and eliminated through the intestinal tract.

Based on their review, the team concludes that, “Ingested nanoparticles appear unlikely to have acute or severe toxic effects at typical levels of exposure.” Nevertheless, they add that the current literature is inadequate to assess whether nanoparticles can accumulate in tissues and have long-term effects or whether they might cause subtle alterations in gut microbial populations. The researchers stress that better methods are needed for correlating particle concentrations used for cell-based assessment of toxicity with the actual likely exposure levels to body cells. Such methods may lead to better predictive value for laboratory in vitro testing, which currently over-predicts toxicity of ingested nanoparticles as compared to in vivo testing.

The researchers focused specifically on ingestion via the gastrointestinal tract which I take to mean that they focused largely on nanoparticles in food (eaten) and liquid (swallowed).

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

Nanoparticle toxicity by the gastrointestinal route: evidence and knowledge gaps by Ingrid L. Bergin; Frank A. Witzmann.  Int. J. of Biomedical Nanoscience and Nanotechnology, 2013 Vol.3, No.1/2, pp.163 – 210.  DOI: 10.1504/IJBNN.2013.054515

I think the abstract further helps to understand the research focus,

The increasing interest in nanoparticles for advanced technologies, consumer products, and biomedical applications has led to great excitement about potential benefits but also concern over the potential for adverse human health effects. The gastrointestinal tract represents a likely route of entry for many nanomaterials, both directly through intentional ingestion or indirectly via nanoparticle dissolution from food containers or by secondary ingestion of inhaled particles. Additionally, increased utilisation of nanoparticles may lead to increased environmental contamination and unintentional ingestion via water, food animals, or fish. The gastrointestinal tract is a site of complex, symbiotic interactions between host cells and the resident microbiome. Accordingly, evaluation of nanoparticles must take into consideration not only absorption and extraintestinal organ accumulation but also the potential for altered gut microbes and the effects of this perturbation on the host. The existing literature was evaluated for evidence of toxicity based on these considerations. Focus was placed on three categories of nanomaterials: nanometals and metal oxides, carbon-based nanoparticles, and polymer/dendrimers with emphasis on those particles of greatest relevance to gastrointestinal exposures.

The article is behind a paywall.

I last mentioned Frank Witzmann here in a May 8, 2013 posting titled, US multicenter (Nano GO Consortium) study of engineered nanomaterial toxicology.