Tag Archives: x-rays

‘Golden’ protein crystals

Yet another use for gold. From a March 14, 2017 news item on Nanowerk (Note: A link has been removed),

Scientists from the London Centre for Nanotechnology (LCN) have revealed how materials such as gold can help create protein crystals. The team hope their findings, published in the journal Scientific Reports (“Protein crystal nucleation in pores”), could aid the discovery of new medicines and treatments. The Lead author; Professor Naomi Chayen states that “Gold doesn’t react with proteins, due to its inert nature, which makes it an ideal material to create crystals”.

Image: Crystals of an antibody peptide complex related to AIDS research Courtesy: LCN

A March 14, 2017 (?) LCN press release, which originated the news item, expands on the theme,

Proteins are crucial to numerous functions in the body – yet scientists are still in the dark about what most of them look like. This is because the most powerful way of revealing the structure of proteins is to turn them into crystals, and then analyse these with X-rays. However, persuading proteins to turn into useful crystals is notoriously difficult. All crystals start from a conception stage when the first molecules come together; this is called nucleation. But reaching nucleation is often difficult as it requires a lot of energy – and many proteins simply can’t overcome this barrier. Scientists also struggle to create medicines that bind to particular proteins – for instance a protein involved in cancer formation, if they don’t know the protein’s structure.

“How can you target a protein if you have no idea what it looks like? It’s like recognising a face in a crowd – you need a picture,” explained Professor Naomi Chayen, lead author of the research.

Forcing molecules together with gold

One technique for allowing proteins to reach their nucleation point is to trap them in tiny holes. This forces the molecules together, which helps them overcome the energy barrier needed to trigger the first crystal. One material that scientists have found to be effective at growing crystals is gold. Creating many holes in the metal creates a substance called porous gold, which acts as a perfect environment for growing crystals, explained Professor Chayen: “Gold doesn’t react with proteins, due to its inert nature, which makes it an ideal material to create crystals. Creating holes in the metal enable it to act a bit like coral, with each hole providing an ideal environment to harbour crystals.”

Creating crystals

In the latest research, the team investigated the best size hole needed to create crystals. They found that a variety of different sized holes produced the highest quality crystals. Most holes were around 5-10nm, just slightly larger than the width of a human hair. Professor Chayen explained: “Imagine walking down a street with many potholes – some of the holes will be big enough for me to step out of, while some will be too small for my foot to fall into. “However, some will be the exact size of my foot, and will trap me in them. This is the same principle as having different pore sizes – it allows us to trap different size protein molecules, enabling them to form crystals.”

She added that the findings which give a simple explanation of why, and under what conditions porous materials can induce protein crystal nucleation may help scientists design porous materials that would produce the highest quality crystals.

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

Protein crystal nucleation in pores by Christo N. Nanev, Emmanuel Saridakis & Naomi E. Chayen. Scientific Reports 7, Article number: 35821 (2017) doi:10.1038/srep35821 Published online: 16 January 2017

This is an open access article.

Drink your spinach juice—illuminate your guts

Contrast agents used for magnetic resonance imaging, x-ray imaging, ultrasounds, and other imaging technologies are not always kind to the humans ingesting them. So, scientists at the University at Buffalo (also known as the State University of New York at Buffalo) have developed a veggie juice that does the job according to a July 11, 2016 news item on Nanowerk (Note: A link has been removed),

The pigment that gives spinach and other plants their verdant color may improve doctors’ ability to examine the human gastrointestinal tract.

That’s according to a study, published in the journal Advanced Materials (“Surfactant-Stripped Frozen Pheophytin Micelles for Multimodal Gut Imaging”), which describes how chlorophyll-based nanoparticles suspended in liquid are an effective imaging agent for the gut.

The University of Buffalo has provided an illustration of the work,

A new UB-led study suggests that chlorophyll-based nanoparticles are an effective imaging agent for the gut. The medical imaging drink, developed to diagnose and treat gastrointestinal illnesses, is made of concentrated chlorophyll, the pigment that makes spinach green. Photo illustration credit: University at Buffalo.

A new UB-led study suggests that chlorophyll-based nanoparticles are an effective imaging agent for the gut. The medical imaging drink, developed to diagnose and treat gastrointestinal illnesses, is made of concentrated chlorophyll, the pigment that makes spinach green. Photo illustration credit: University at Buffalo.

A July 11, 2016 University at Buffalo (UB) news release (also on EurekAlert) by Cory Nealon, which originated the news item, expands on the theme,

“Our work suggests that this spinach-like, nanoparticle juice can help doctors get a better look at what’s happening inside the stomach, intestines and other areas of the GI tract,” says Jonathan Lovell, PhD, assistant professor in the Department of Biomedical Engineering, a joint program between UB’s School of Engineering and Applied Sciences and the Jacobs School of Medicine and Biomedical Sciences at UB, and the study’s corresponding author.

To examine the gastrointestinal tract, doctors typically use X-rays, magnetic resonance imaging or ultrasounds, but these techniques are limited with respect to safety, accessibility and lack of adequate contrast, respectively.

Doctors also perform endoscopies, in which a tiny camera attached to a thin tube is inserted into the patient’s body. While effective, this procedure is challenging to perform in the small intestine, and it can cause infections, tears and pose other risks.

The new study, which builds upon Lovell’s previous medical imaging research, is a collaboration between researchers at UB and the University of Wisconsin-Madison. It focuses on Chlorophyll a, a pigment found in spinach and other green vegetables that is essential to photosynthesis.

In the laboratory, researchers removed magnesium from Chlorophyll a, a process which alters the pigment’s chemical structure to form another edible compound called pheophytin. Pheophytin plays an important role in photosynthesis, acting as a gatekeeper that allows electrons from sunlight to enter plants.

Next, they dissolved pheophytin in a solution of soapy substances known as surfactants. The researchers were then able to remove nearly all of the surfactants, leaving nearly pure pheophytin nanoparticles.

The drink, when tested in mice, provided imaging of the gut in three modes: photoacoustic imaging, fluorescence imaging and positron emission tomography (PET). (For PET, the researchers added to the drink Copper-64, an isotope of the metal that, in small amounts, is harmless to the human body.)

Additional studies are needed, but the drink has commercial potential because it:

·         Works in different imaging techniques.

·         Moves stably through the gut.

·         And is naturally consumed in the human diet already.

In lab tests, mice excreted 100 percent of the drink in photoacoustic and fluorescence imaging, and nearly 93 percent after the PET test.

“The veggie juice allows for techniques that are not commonly used today by doctors for imaging the gut like photoacoustic, PET, and fluorescence,” Lovell says. “And part of the appeal is the safety of the juice.”

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

Surfactant-Stripped Frozen Pheophytin Micelles for Multimodal Gut Imaging by Yumiao Zhang, Depeng Wang, Shreya Goel, Boyang Sun, Upendra Chitgupi, Jumin Geng, Haiyan Sun, Todd E. Barnhart, Weibo Cai, Jun Xia, and Jonathan F. Lovell. Advanced Materials DOI: 10.1002/adma.201602373 Version of Record online: 11 JUL 2016

© 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim

This paper is behind a paywall.

X-raying fungus on paper to conserve memory

Civilization is based on memory. Our libraries and archives serve as memories of how things are made, why we use certain materials rather than others, how the human body is put together, what the weather patterns have been, etc. For centuries we have preserved our memories on paper. While this has many advantages, there are some drawbacks including fungus infestations.

A July 21, 2015 news item on ScienceDaily describes how a technique used to x-ray rocks has provided insights into paper and its fungal infestations,

Believe it or not: X-ray works a lot better on rocks than on paper. This has been a problem for conservators trying to save historical books and letters from the ravages of time and fungi. They frankly did not know what they were up against once the telltale signs of vandals such as Dothidales or Pleosporales started to spot the surface of their priceless documents

Now Diwaker Jha, an imaging specialist from Department of Chemistry, University of Copenhagen, has managed to adapt methods developed to investigate interiors of rocks to work on paper too, thus getting a first look at how fungus goes about infesting paper. …

A July 21, 2015 University of Copenhagen press release (also on EurekAlert), which originated the news item, expands on the theme,

This is good news for paper conservators and others who wish to study soft materials with X-ray tomography. “Rocks are easy because they are hard. The X-ray images show a very good contrast between the solid and the pores or channels, which are filled with low density materials such as air or fluids. In this case, however, paper and fungi, both are soft and carbon based, which makes them difficult to distinguish,” says Diwaker.

Diwaker Jha is a PhD student in the NanoGeoScience group, which is a part of the Nano-Science Center at Department of Chemistry. He investigates methods to improve imaging techniques used by chemists and physicists to investigate how fluids move in natural porous materials. At a recent conference, he was presenting an analysis method he developed for X-ray tomography data, for which he was awarded the Presidential Scholar Award by the Microscopy Society of America. And this sparked interest with a conservator in the audience.

Hanna Szczepanowska works as a research conservator with the Smithsonian Institution in the USA. She had been wondering how fungi interact with the paper. Does it sit on the surface, or does it burrow deeper? If they are surface dwellers, it should be easy to just brush them off, but no such luck, says Jha.

“As it turns out, microscopic fungi that infest paper grow very much the same way as mushrooms on a forest floor. However, unlike mushrooms, where the fruiting body emerges out of the soil to the surface, here the fruiting bodies can be embedded within the paper fibres, making it difficult to isolate them. This is not great news for conservators because the prevalent surface cleaning approaches are not adequate,” explains Diwaker Jha.

In working out a way to see into the paper, Jha investigated a 17th century letter on a handmade sheet and a 1920 engraving on machine-made paper. Compared with mushrooms, these fungi are thousands of times smaller, which required an advanced X-ray imaging technique available at the European Synchrotron Radiation Facility (ESRF), Grenoble, France. The technique is very similar to medical tomography (CT scanning) done at hospitals but in Grenoble the X-ray is produced by electrons accelerated to about the speed of light in an 844 meter long circular tube. A handy comparison: “If I were to use medical X-ray tomography to look at an Olympic village, I would be able to make out only the stadium. With the synchrotron based X-ray tomography, I would be able to distinguish individual blades of grass on the field..”

Diwaker hopes that conservators will be able to use the new insight to develop conservation strategies not just for paper artefacts but for combating biodegradation on a host of other types of cultural heritage materials. And that the developed methods can be extended to other studies related to soft matter.

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

Morphology and characterization of Dematiaceous fungi on a cellulose paper substrate using synchrotron X-ray microtomography, scanning electron microscopy and confocal laser scanning microscopy in the context of cultural heritage by H. M. Szczepanowska, D. Jha, and Th. G. Mathia. Anal. At. Spectrom. (Journal of Analystical Atomic Spetrometry), 2015,30, 651-657 DOI: 10.1039/C4JA00337C First published online 27 Nov 2014

This paper is behind a paywall. By the way, it is part of something the journal calls a themed collection:  Synchrotron radiation and neutrons in art and archaeology. Clicking on the ‘themed collection’ link will give you a view of the collection, i.e., titles, authors and brief abstracts.

Observing photo exposure one nanoscale grain at a time

A June 9, 2015 news item on Nanotechnology Now highlights research into a common phenomenon, photographic exposure,

Photoinduced chemical reactions are responsible for many fundamental processes and technologies, from energy conversion in nature to micro fabrication by photo-lithography. One process that is known from everyday’s life and can be observed by the naked eye, is the exposure of photographic film. At DESY’s [Deutsches Elektronen-Synchrotron] X-ray light source PETRA III, scientists have now monitored the chemical processes during a photographic exposure at the level of individual nanoscale grains in real-time. The advanced experimental method enables the investigation of a broad variety of chemical and physical processes in materials with millisecond temporal resolution, ranging from phase transitions to crystal growth. The research team lead by Prof. Jianwei (John) Miao from the University of California in Los Angeles and Prof. Tim Salditt from the University of Göttingen report their technique and observations in the journal Nature Materials.

A June 9, 2015 DESY press release (also on EurekAlert), which originated the news item, provides more detail about the research,

The researchers investigated a photographic paper (Kodak linagraph paper Type 2167 or “yellow burn paper”) that is often used to determine the position of the beam at X-ray experiments. “The photographic paper we looked at is not specially designed for X-rays. It works by changing its colour on exposure to light or X-rays,” explains DESY physicist Dr. Michael Sprung, head of the PETRA III beamline P10 where the experiments took place.

The X-rays were not only used to expose the photographic paper, but also to analyse changes of its inner composition at the same time. The paper carries a photosensitive film of a few micrometre thickness, consisting of tiny silver bromide grains dispersed in a gelatine matrix, and with an average size of about 700 nanometres. A nanometre is a millionth of a millimetre. When X-rays impinge onto such a crystalline grain, they are diffracted in a characteristic way, forming a unique pattern on the detector that reveals properties like crystal lattice spacing, chemical composition and orientation. “We could observe individual silver bromide grains within the ‘burn’ paper since the X-ray beam had a size of only 270 by 370 nanometres – smaller than the average grain,” says Salditt, who is a partner of DESY in the construction and operation of the GINIX (Göttingen Instrument for Nano-Imaging with X-Rays) at beamline P10.

The X-ray exposure starts the photolysis from silver bromide to produce silver. An absorbed X-ray photon can create many photolytic silver atoms, which grow and agglomerate at the surface and inside the silver bromide grain. The scientists observed how the silver bromide grains were strained, began to turn in the gelatine matrix and broke up into smaller crystallites as well as the growth of pure silver nano grains. The exceptionally bright beam of PETRA III together with a high-speed detector enabled the ‘filming’ of the process with up to five milliseconds temporal resolution. “We observed, for the first time, grain rotation and lattice deformation during photoinduced chemical reactions,” emphasises Miao. “We were actually surprised how fast some of these single grains rotate,” adds Sprung. “Some spin almost one time every two seconds.”

“As advanced synchrotron light sources are currently under rapid development in the US, Europe and Asia,” the authors anticipate that “in situ X-ray nanodiffraction, which enables to measure atomic resolution diffraction patterns with several millisecond temporal resolution, can be broadly applied to investigate phase transitions, chemical reactions, crystal growth, grain boundary dynamics, lattice expansion, and contraction in materials science, nanoscience, physics, and chemistry.”

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

Grain rotation and lattice deformation during photoinduced chemical reactions revealed by in situ X-ray nanodiffraction by Zhifeng Huang, Matthias Bartels, Rui Xu, Markus Osterhoff, Sebastian Kalbfleisch, Michael Sprung, Akihiro Suzuki, Yukio Takahashi, Thomas N. Blanton, Tim Salditt, & Jianwei Miao. Nature Materials (2015) doi:10.1038/nmat4311 Published online 08 June 2015

This paper is behind a paywall.

Making x-ray measurements more accurate

Apparently the method for establishing x-ray measurements is from the 1970s and the folks at the US National Institute of Standards and Technology (NIST) feel it’s time for a new technique. From a March 9, 2015 NIST news release (also on EurekAlert),

Criminal justice, cosmology and computer manufacturing may not look to have much in common, but these and many other disparate fields all depend on sensitive measurements of X-rays. Scientists at the National Institute of Standards and Technology (NIST) have developed a new method* to reduce uncertainty in X-ray wavelength measurement that could provide improvements awaited for decades.

Accurate measurement of X-ray wavelengths depends critically on the ability to measure angles very precisely and with very little margin for error. NIST’s new approach is the first major advance since the 1970s in reducing certain sources of error common in X-ray angle measurement.

Many of us associate X-rays with a doctor’s office, but the uses for these energetic beams go far beyond revealing our skeletons. The ability to sense X-rays at precise wavelengths allows law enforcement to detect and identify trace explosives, or astrophysicists to better understand cosmic phenomena. It all comes down to looking very closely at the X-ray spectrum and measuring the precise position of lines within it. Those lines represent specific wavelengths–which are associated with specific energies–of X-rays that are emitted by the subject being studied. Each material has its own, unique X-ray “fingerprint.”

But a slight error in angle measurement can skew the results, with consequences for quantum theories, research and manufacturing. “While many fields need good X-ray reference data, many of the measurements that presently fill standard reference databases are not great–most data were taken in the 1970s and are often imprecise,” says NIST’s Larry Hudson.

X-ray wavelengths are measured by passing the beam through special crystals and very carefully measuring the angle that exiting rays make with the original beam. While the physics is different, the technique is analogous to the way a prism will split white light into different colors coming out at different angles.

The crystal is typically mounted on a rotating device that spins the crystal to two different positions where a spectral line is observed. The angle between the two is measured–this is a neat geometry trick that determines the line’s position more precisely than a single measurement would, while also cancelling out some potential errors. One inevitable limit is the accuracy of the digital encoder, the device that translates the rotation of the crystal to an angle measurement.

The news release goes on to describe the new technique,

Hudson and his co-authors have found a way to dramatically reduce the error in that measurement. Their new approach uses laser beams bouncing off a mirrored polygon that is rotated on the same shaft that would carry the crystal. The approach allows the team to use additional mathematical shortcuts to their advantage. With new NIST sensing instrumentation and analysis, X-ray angles can now be measured routinely with an uncertainty of 0.06 arcseconds–an accuracy more than three times better than the uncalibrated encoder.

Hudson describes this reduction as significant enough to set world records in X-ray wavelength measurement. “If a giant windshield wiper stretched from Washington D.C. to New York City (364 kilometers) and were to sweep out the angle of one of these errors, its tip would move less than the width of a DVD,” he says.

What do these improvements mean for the fields that depend on X-ray sensing? For one thing, calibrating measurement devices to greater precision will provide better understanding of a host of newly designed materials, which often have complicated crystal structures that give rise to unusual effects such as high-temperature superconductivity. The team’s efforts will permit better understanding of the relationship between the structures and properties of novel materials.

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

A simple method for high-precision calibration of long-range errors in an angle encoder using an electronic nulling by Mark N Kinnane, Lawrence T Hudson, Albert Henins, and Marcus H Mendenhall. Metrologia Volume 52 Number 2 doi:10.1088/0026-1394/52/2/244

This is an open access paper,

For anyone curious about arcseconds, you can find an explanation in this Wikipedia entry titled Minute of art. Briefly, imagine a 360 degree circle where one degree equals one arcminute and one arcsecond is 1/60 of that minute.

Nanoparticles in 3D courtesy of x-rays

A Feb. 4, 2015 Deutsches Elektronen-Synchrotron (DESY) press release (also on EurekAlert) announces a 3D first,

For the first time, a German-American research team has determined the three-dimensional shape of free-flying silver nanoparticles, using DESY’s X-ray laser FLASH. The tiny particles, hundreds of times smaller than the width of a human hair, were found to exhibit an unexpected variety of shapes, as the physicists from the Technical University (TU) Berlin, the University of Rostock, the SLAC National Accelerator Laboratory in the United States and from DESY report in the scientific journal Nature Communications. Besides this surprise, the results open up new scientific routes, such as direct observation of rapid changes in nanoparticles.

The press release goes on to describe the work in more detail,

“The functionality of nanoparticles is linked to their geometric form, which is often very difficult to determine experimentally,” explains Dr. Ingo Barke from the University of Rostock. “This is particularly challenging when they are present as free particles, that is, in the absence of contact with a surface or a liquid.”

The nanoparticle shape can be revealed from the characteristic way how it scatters X-ray light. Therefore, X-ray sources like DESY’s FLASH enable a sort of super microscope into the nano-world. So far, the spatial structure of nanoparticles has been reconstructed from multiple two-dimensional images, which were taken from different angles. This procedure is uncritical for particles on solid substrates, as the images can be taken from many different angles to uniquely reconstruct their three-dimensional shape.

“Bringing nanoparticles into contact with a surface or a liquid can significantly alter the particles, such that you can no longer see their actual form,” says Dr. Daniela Rupp from the TU Berlin. A free particle, however, can only be measured one time in flight before it either escapes or is destroyed by the intense X-ray light. Therefore, the scientists looked for a way to record the entire structural information of a nanoparticle with a single X-ray laser pulse.

To achieve this goal, the scientists led by Prof. Thomas Möller from the TU Berlin and Prof. Karl-Heinz Meiwes-Broer and Prof. Thomas Fennel from the University of Rostock employed a trick. Instead of taking usual small-angle scattering images, the physicists recorded the scattered X-rays in a wide angular range. “This approach virtually captures the structure from many different angles simultaneously from a single laser shot,” explains Fennel.

The researchers tested this method on free silver nanoparticles with diameters of 50 to 250 nanometres (0.00005 to 0.00025 millimetres). The experiment did not only verify the feasibility of the tricky method, but also uncovered the surprising result that large nanoparticles exhibit a much greater variety of shapes than expected.

The shape of free nanoparticles is a result of different physical principles, particularly the particles’ effort to minimize their energy. Consequently, large particles composed of thousands or millions of atoms often yield predictable shapes, because the atoms can only be arranged in a particular way to obtain an energetically favourable state.

In their experiment, however, the researchers observed numerous highly symmetrical three-dimensional shapes, including several types known as Platonic and Archimedean bodies. Examples include the truncated octahedron (a body consisting of eight regular hexagons and six squares) and the icosahedron (a body made up of twenty equilateral triangles). The latter is actually only favourable for extremely small particles consisting of few atoms, and its occurrence with free particles of this size was previously unknown. “The results show that metallic nanoparticles retain a type of memory of their structure, from the early stages of growth to a yet unexplored size range,” emphasizes Barke.

Due to the large variety of shapes, it was especially important to use a fast computational method so that the researchers were capable of mapping the shape of each individual particle. The scientists used a two-step process: the rough shape was determined first and then refined using more complex simulations on a super computer. This approach turned out to be so efficient that it could not only determine various shapes reliably, but could also differentiate between varying orientations of the same shape.

This new method for determining the three-dimensional shape and orientation of nanoparticles with a single X-ray laser shot opens up a wide spectrum of new research directions. In future projects, particles could be directly “filmed” in three dimensions during growth or during phase changes. “The ability to directly film the reaction of a nanoparticle to an intense flash of X-ray light has been a dream for many physicists – this dream could now come true, even in 3D!,” emphasises Rupp.

The researchers have provided an image showing their work,

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle. Credit: Hannes Hartmann/University of Rostock

Caption: This is a wide-angle X-ray diffraction image of a truncated twinned tetrahedra nanoparticle.
Credit: Hannes Hartmann/University of Rostock

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

The 3D-architecture of individual free ​silver nanoparticles captured by X-ray scattering by Ingo Barke, Hannes Hartmann, Daniela Rupp, Leonie Flückiger, Mario Sauppe, Marcus Adolph, Sebastian Schorb, Christoph Bostedt, Rolf Treusch, Christian Peltz, Stephan Bartling, Thomas Fennel, Karl-Heinz Meiwes-Broer, & Thomas Möller. Nature Communications 6, Article number: 6187 doi:10.1038/ncomms7187 Published 04 February 2015

This article is open access.

Soybeans and nanoparticles redux

If you read the Feb. 6, 2013 news release on EurekAlert too quickly you might not realize that only one of the two types of the tested nanoparticles adversely affects soybean plants,

Two of the most widely used nanoparticles (NPs) accumulate in soybeans — second only to corn as a key food crop in the United States — in ways previously shown to have the potential to adversely affect the crop yields and nutritional quality, a new study has found. It appears in the journal ACS Nano. [emphasis mine]

Jorge L. Gardea-Torresdey and colleagues cite rapid increases in commercial and industrial uses of NPs, the building blocks of a nanotechnology industry projected to put $1 trillion worth of products on the market by 2015. Zinc oxide and cerium dioxide are among today’s most widely used NPs. Both are used in cosmetics, lotions, sunscreens and other products. They eventually go down the drain, through municipal sewage treatment plants, and wind up in the sewage sludge that some farmers apply to crops as fertilizer. Gardea-Torresdey’s team previously showed that soybean plants grown in hydroponic solutions accumulated zinc and cerium dioxide in ways that alter plant growth and could have health implications.

The question remained, however, as to whether such accumulation would occur in the real-world conditions in which farmers grow soybeans in soil, rather than nutrient solution. Other important questions included the relationship of soybean plants and NPs, the determination of their entrance into the food chain, their biotransformation and toxicity and the possible persistence of these products into the next plant generation. Their new study, performed at two world-class synchrotron facilities — the SLAC National Accelerator Laboratory in California and the European Synchrotron Radiation Facility in Grenoble, France, addressed those questions. “To our knowledge, this is the first report on the presence of cerium dioxide and zinc compounds in the reproductive/edible portions of the soybean plant grown in farm soil with cerium dioxide and zinc oxide nanoparticles. In addition, our results have shown that cerium dioxide NPs in soil can be taken up by food crops and are not biotransformed in soybeans. [emphasis mine] This suggests that cerium dioxide NPs can reach the food chain and the next soybean plant generation, with potential health implications,” the study notes.

The University of Texas El Paso Feb. 6, 2013 news release provides more detail and more clarity about the results of the research ,

Experiments led by Jorge Gardea-Torresdey, Ph.D., of The University of Texas at El Paso (UTEP) have shown that certain man-made nanoparticles that land in soil can be transferred from the roots of plants to the grains, thus entering the food supply via crops grown for human consumption.

Cerium dioxide, which is commonly used in sunscreens and oil refining, remained intact when it was absorbed by the plant, and was transferred all the way into the edible soybean grains. [emphasis mine]

On the other hand, zinc oxide – commonly used in sunscreens and cosmetics – was transferred to the grain, but had broken down to a nontoxic form. [emphasis mine]

To track the nanoparticles’ route within the plants, the researchers used the intense beams of X-rays from the SLAC National Accelerator Laboratory’s Stanford Synchrotron Radiation Lightsource (SSRL) and the European Synchrotron Radiation Facility (ESRF) in Grenoble, France. The X-rays also helped reveal whether or not the nanoparticles were chemically transformed in the process.

While studies are under way, Gardea-Torresdey says there is currently little information on the potential health implications of nanoparticles.

UTEP has produced a video titled, UTEP Study Shows Engineered Nanoparticles Can Enter Food Supply. This piece, which features Gardea-Torresdey and a student,  seems to be less about the study and more about the benefits of studying at UTEP and the impact of the Latino community in the US,

Here’s a citation and a link to the article (Note: This work bears a remarkable resemblance to the work mentioned in my Aug. 20, 2012 posting about soybeans and nanoparticles, not least because the studies share three or more authors),

In Situ Synchrotron X-ray Fluorescence Mapping and Speciation of CeO2 and ZnO Nanoparticles in Soil Cultivated Soybean (Glycine max) by Jose A. Hernandez-Viezcas, Hiram Castillo-Michel, Joy Cooke Andrews , Marine Cotte , Cyren Rico, Jose R. Peralta-Videa, Yuan Ge, John H. Priester, Patricia Ann Holden, and Jorge L. Gardea-Torresdey. ACS Nano, DOI: 10.1021/nn305196q Publication Date (Web): January 15, 2013

Copyright © 2013 American Chemical Society

The article is behind a paywall.