Tag Archives: Missouri University of Science and Technology

Shades of the Nokia Morph: a smartphone than conforms to your wrist

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A March 16, 2017 news item on Nanowerk brought back some memories for me,

Some day, your smartphone might completely conform to your wrist, and when it does, it might be covered in pure gold, thanks to researchers at Missouri University of Science and Technology.

Nokia, a Finnish telecommunications company, was promoting its idea for a smartphone ‘and more’ that could be worn around your wrist in a concept called the Morph. It was introduced in 2008 at the Museum of Modern Art in New York City (see my March 20, 2010 posting for one of my last updates on this moribund project). Here’s Nokia’s Morph video (almost 6 mins.),

Getting back to the present day, here’s what the Missouri researchers are working on,

An example of a gold foil peeled from single crystal silicon. Reprinted with permission from Naveen Mahenderkar et al., Science [355]:[1203] (2017)

A March 16, 2017 Missouri University of Science and Technology news release, by Greg Katski, which originated the news item, provides more details about this Missouri version (Note: A link has been removed),

Writing in the March 17 [2017] issue of the journal Science, the S&T researchers say they have developed a way to “grow” thin layers of gold on single crystal wafers of silicon, remove the gold foils, and use them as substrates on which to grow other electronic materials. The research team’s discovery could revolutionize wearable or “flexible” technology research, greatly improving the versatility of such electronics in the future.

According to lead researcher Jay A. Switzer, the majority of research into wearable technology has been done using polymer substrates, or substrates made up of multiple crystals. “And then they put some typically organic semiconductor on there that ends up being flexible, but you lose the order that (silicon) has,” says Switzer, Donald L. Castleman/FCR Endowed Professor of Discovery in Chemistry at S&T.

Because the polymer substrates are made up of multiple crystals, they have what are called grain boundaries, says Switzer. These grain boundaries can greatly limit the performance of an electronic device.

“Say you’re making a solar cell or an LED,” he says. “In a semiconductor, you have electrons and you have holes, which are the opposite of electrons. They can combine at grain boundaries and give off heat. And then you end up losing the light that you get out of an LED, or the current or voltage that you might get out of a solar cell.”

Most electronics on the market are made of silicon because it’s “relatively cheap, but also highly ordered,” Switzer says.

“99.99 percent of electronics are made out of silicon, and there’s a reason – it works great,” he says. “It’s a single crystal, and the atoms are perfectly aligned. But, when you have a single crystal like that, typically, it’s not flexible.”

By starting with single crystal silicon and growing gold foils on it, Switzer is able to keep the high order of silicon on the foil. But because the foil is gold, it’s also highly durable and flexible.

“We bent it 4,000 times, and basically the resistance didn’t change,” he says.

The gold foils are also essentially transparent because they are so thin. According to Switzer, his team has peeled foils as thin as seven nanometers.

Switzer says the challenge his research team faced was not in growing gold on the single crystal silicon, but getting it to peel off as such a thin layer of foil. Gold typically bonds very well to silicon.

“So we came up with this trick where we could photo-electrochemically oxidize the silicon,” Switzer says. “And the gold just slides off.”

Photoelectrochemical oxidation is the process by which light enables a semiconductor material, in this case silicon, to promote a catalytic oxidation reaction.

Switzer says thousands of gold foils—or foils of any number of other metals—can be made from a single crystal wafer of silicon.

The research team’s discovery can be considered a “happy accident.” Switzer says they were looking for a cheap way to make single crystals when they discovered this process.

“This is something that I think a lot of people who are interested in working with highly ordered materials like single crystals would appreciate making really easily,” he says. “Besides making flexible devices, it’s just going to open up a field for anybody who wants to work with single crystals.”

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

Epitaxial lift-off of electrodeposited single-crystal gold foils for flexible electronics by Naveen K. Mahenderkar, Qingzhi Chen, Ying-Chau Liu, Alexander R. Duchild, Seth Hofheins, Eric Chason, Jay A. Switzer. Science  17 Mar 2017: Vol. 355, Issue 6330, pp. 1203-1206 DOI: 10.1126/science.aam5830

This paper is behind a paywall.

Boron nitride sponges for oil spill cleanups

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The best part of the news is that the scientists are ready to test these sponges in industrial trials but first here’s why the Australians are so excited about the work from a Dec. 1, 2015 news item on Azonano,

Deakin University scientists have manufactured a revolutionary material that can clean up oil spills, which could save the earth from potential future disasters such as any repeat of the 2010 Gulf Coast BP disaster that wreaked environmental havoc and cost a reported $40 billion.

The major breakthrough material, which literally absorbs the oil like a sponge, is the result of support from the Australian Research Council and is now ready to be trialled by industry after two years of refinement in the laboratory at Deakin’s Institute for Frontier Materials (IFM).

Alfred Deakin Professor Ying (Ian) Chen, the lead author on a paper which outlines the team’s breakthrough in today’s edition of Nature Communications, said the material was the most exciting advancement in oil spill clean-up technology in decades.

Oil spills are a global problem and wreak havoc on our aquatic ecosystems, not to mention cost billions of dollars in damage.

“Everyone remembers the Gulf Coast disaster, but here in Australia they are a regular problem, and not just in our waters. Oil spills from trucks and other vehicles can close freeways for an entire day, again amounting to large economic losses. Professor Chen

But current methods of cleaning up oil spills are inefficient and unsophisticated, taking too long, causing ongoing and expensive damage, which is why the development of our technology was supported by the Australian Research Council.

“We are so excited to have finally got to this stage after two years of trying to work out how to turn what we knew was a good material into something that could be practically used.

A Nov. 30, 2015 Deakin University media release, which originated the news item, provides some technical details,

“In 2013 we developed the first stage of the material, but it was simply a powder. This powder had absorption capabilities, but you cannot simply throw powder onto oil – you need to be able to bind that powder into a sponge so that we can soak the oil up, and also separate it from water.”

The lead author on the paper, IFM scientist Dr Weiwei Lei,) an Australian Research Council Discovery Early Career Research Awardee, said turning the powder into a sponge was a big challenge.

“But we have finally done it by developing a new production technique,” Dr Lei said.

“The ground-breaking material is called a boron nitride nanosheet, which is made up of flakes which are just several nanometers (one billionth of a meter) in thickness with tiny holes which can increase its surface area per gram to effectively the size of 5.5 tennis courts.”

The research team, which included scientists from Drexel University, Philadelphia, and Missouri University of Science and Technology, started with boron nitride powder known as “white graphite” and broke it into atomically thin sheets that were used to make a sponge.

“The pores in the nanosheets provide the surface area to absorb oils and organic solvents up to 33 times its own weight,” Dr Lei said.

Professor Yury Gogotsi from Drexel University said boron nitride nanosheets did not burn, could withstand flame, and be used in flexible and transparent electrical and heat insulation, as well as many other applications.

“We are delighted that support from the Australian Research Council allowed us to participate in this interesting study and we could help our IFM colleagues to model and better understand this wonderful material, ” Professor Gogotsi said.

Professor Vadym Mochalin from Missouri University of Science and Technology said the mechanochemical technique developed meant it was possible to produce high-concentration stable aqueous colloidal solutions of boron nitride sheets, which could then be transformed into the ultralight porous aerogels and membranes for oil clean-up.

“The use of computational modelling helped us to understand the intimate details of this novel mechanochemical exfoliation process. It is a nice illustration of the power, which combined experimental plus modelling approach offers researchers nowadays.”

The research team is now ready to have their “sponge” trialled by industry. [emphasis mine]

The nanotechnology team at IFM has been working on boron nitride nanomaterials for two decades and is an internationally recognised leader in boron nitride nanotubes and nanosheets.

There was at least one other team working on  sponges, all these are composed of carbon nanotubes, for oil spills (mentioned in my April 17, 2012 posting) but they don’t seem to have been able to get their work out of the laboratory.

Here’s a link to and a citation for boron nitride sponges,

Boron nitride colloidal solutions, ultralight aerogels and freestanding membranes through one-step exfoliation and functionalization by Weiwei Lei, Vadym N. Mochalin, Dan Liu, Si Qin, Yury Gogotsi, & Ying Chen. Nature Communications 6, Article number: 8849 doi:10.1038/ncomms9849 Published 27 November 2015

This is an open access paper.

Nanoscale metal oxides and lung cells

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Bear in mind while reading further that all of this research has not taken place in any situation resembling real life conditions: researchers at the Missouri University of Science and Technology (Missouri S&T; located in the US) have found that metal oxides at the nanoscale can be highly toxic to human lung cells according to a Jan. 28, 2014 news item on Nanowerk (Note: A link has been removed),

Nanoparticles are used in all kinds of applications — electronics, medicine, cosmetics, even environmental clean-ups. More than 2,800 commercially available applications are now based on nanoparticles, and by 2017, the field is expected to bring in nearly $50 billion worldwide.

But this influx of nanotechnology is not without risks, say researchers at Missouri University of Science and Technology.

“There is an urgent need to investigate the potential impact of nanoparticles on health and the environment,” says Yue-Wern Huang, professor of biological sciences at Missouri S&T.

Huang and his colleagues have been systematically studying the effects of transition metal oxide nanoparticles on human lung cells (“Cytotoxicity in the age of nano: The role of fourth period transition metal oxide nanoparticle physicochemical properties”). These nanoparticles are used extensively in optical and recording devices, water purification systems, cosmetics and skin care products, and targeted drug delivery, among other applications.

The Jan. 27, 2014 Missouri S&T news release by Linda Fulps, which originated the news item, describes the research in more detail,

“In their typical coarse powder form, the toxicity of these substances is not dramatic,” says Huang. “But as nanoparticles with diameters of only 16-80 nanometers, the situation changes significantly.”

The researchers exposed both healthy and cancerous human lung cells to nanoparticles composed of titanium, chromium, manganese, iron, nickel, copper and zinc compounds — transition metal oxides that are on the fourth row of the periodic table. The researchers discovered that the nanoparticles’ toxicity to the cells, or cytotoxicity, increased as they moved right on the periodic table.

“About 80 percent of the cells died in the presence of nanoparticles of copper oxide and zinc oxide,” says Huang. “These nanoparticles penetrated the cells and destroyed their membranes. The toxic effects are related to the nanoparticles’ surface electrical charge and available docking sites.”

Huang says that certain nanoparticles released metal ions — called ion dissolution — which also played a significant role in cell death.

Huang is now working on new research that may help reduce nanoparticles’ toxicity and shed light on how nanoparticles interact with cells.

“We are coating toxic zinc oxide nanoparticles with non-toxic nanoparticles to see if zinc oxide’s toxicity can be reduced,” Huang says. “We hope this can mitigate toxicity without compromising zinc oxide’s intended applications. We’re also investigating whether nanoparticles inhibit cell division and influence cell cycle.”

Concerning results? Yes. But, before determining how alarmed you should be, there are a few questions you might want to ask while reading the news release and/or the research paper :

  1. How were these cells exposed to the metal nanoparticles? ‘Breathing’ or were they sitting in a solution?
  2. What was the concentration of metal nanoparticles? (even good things can be bad for you at high concentrations)

This isn’t an attempt to dismiss the findings but rather to point out how much painstaking research has to take place before conclusions of any kind can be drawn. It’s why scientists tend to quite careful in their comments.

In looking at this work, I was reminded of the research into ‘nanosunscreens’ and concerns about the metal oxide nanoparticles (zinc oxides and/or titanium dioxide) penetrating the skin barrier and building up to toxic levels in the body.  In an Oct. 4, 2012 posting about zinc oxide nanoparticles and penetrating the skin barrier, I mentioned this in the context of some then recent research at Bath University (UK),

I missed the fact that this study was an in vitro test, which is always less convincing than in vivo testing. In my Nov. 29, 2011 posting about some research into nano zinc oxide I mentioned in vitro vs. in vivo testing and Brian Gulson’s research,

I was able to access the study and while I’m not an expert by any means I did note that the study was ‘in vitro’, in this case, the cells were on slides when they were being studied. It’s impossible to draw hard and fast conclusions about what will happen in a body (human or otherwise) since there are other systems at work which are not present on a slide.

…

… here’s what Brian Gulson had to say about nano zinc oxide concentrations in his work and about a shortcoming in his study (from an Australian Broadcasting Corporation [ABC] Feb. 25, 2010 interview with Ashley Hall,

BRIAN GULSON: I guess the critical thing was that we didn’t find large amounts of it getting through the skin. The sunscreens contain 18 to 20 per cent zinc oxide usually and ours was about 20 per zinc. So that’s an awful lot of zinc you’re putting on the skin but we found tiny amounts in the blood of that tracer that we used.

ASHLEY HALL: So is it a significant amount?

BRIAN GULSON: No, no it’s really not.

ASHLEY HALL: But Brian Gulson is warning people who use a lot of sunscreen over an extended period that they could be at risk of having elevated levels of zinc.

BRIAN GULSON: Maybe with young children where you’re applying it seven days a week, it could be an issue but I’m more than happy to continue applying it to my grandchildren.

ASHLEY HALL: This study doesn’t shed any light on the question of whether the nano-particles themselves played a part in the zinc absorption.

BRIAN GULSON: That was the most critical thing. This isotope technique cannot tell whether or not it’s a zinc oxide nano-particle that got through skin or whether it’s just zinc that was dissolved up in contact with the skin and then forms zinc ions or so-called soluble ions. So that’s one major deficiency of our study.

Of course, I have a question about Gulson’s conclusion  that very little of the nano zinc oxide was penetrating the skin based on blood and urine samples taken over the course of the study. Is it possible that after penetrating the skin it was stored in the cells  instead of being eliminated?

Here’s a link to and a citation for Yue-Wern Huang and his team’s latest research,

Cytotoxicity in the age of nano: The role of fourth period transition metal oxide nanoparticle physicochemical properties by Charles C. Chusuei, Chi-Heng Wu, Shravan Mallavarapu, Fang Yao Stephen Hou, Chen-Ming Hsu, Jeffrey G. Winiarz, Robert S. Aronstam, Yue-Wern Huang. Chemico-Biological Interactions, Volume 206, Issue 2, 25 November 2013, Pages 319–326.

This paper is behind a paywall.

A ‘glass jaw’ might turn out to be a good thing

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I don’t know if the phrase ‘glass jaw’ is used much any more but it was a term for someone who couldn’t ‘take’ a punch to the jaw (i.e., the person was instantly rendered unconscious or helplessly groggy). If scientists at Missouri University of Science and Technology (Missouri S&T)  have their way, the phrase ‘glass jaw’ will have a new meaning as per the July 26, 2012 news item on ScienceDaily,

Researchers at Missouri University of Science and Technology have developed a type of glass implant that could one day be used to repair injured bones in the arms, legs and other areas of the body that are most subject to the stresses of weight.

This marks the first time researchers have shown a glass implant strong enough to bear weight can also integrate with bone and promote bone growth, says lead researcher Dr. Mohamed N. Rahaman, professor of materials science and engineering at Missouri S&T.

The July 26, 2013 Missouri S&T news release by Andrew Careaga, which originated the news item, describes the work leading to this latest research,

In previous work, the Missouri S&T researchers developed a glass implant strong enough to handle the weight and pressure of repetitive movement, such as walking or lifting. In their most recent study, published in the journal Acta Biomaterialia, the research team reported that the glass implant, in the form of a porous scaffolding, also integrates with bone and promotes bone growth.

This combination of strength and bone growth opens new possibilities for bone repair, says Rahaman, who also directs Missouri S&T’s Center for Biomedical Science and Engineering, where the research was conducted.

The news release then goes on to describe one of the problems with using synthetic materials for bone repair and explains how this latest research addresses the issue,

Conventional approaches to structural bone repair involve either the use of a porous metal, which does not reliably heal bone, or a bone allograft from a cadaver. Both approaches are costly and carry risks, Rahaman says. He thinks the type of glass implant developed in his center could provide a more feasible approach for repairing injured bones. The glass is bioactive, which means that it reacts when implanted in living tissue and convert to a bone-like material.

In their latest research, Rahaman and his colleagues implanted bioactive glass scaffolds into sections of the calvarial bones (skullcaps) of laboratory rats, then examined how well the glass integrated with the surrounding bone and how quickly new bone grew into the scaffold. The scaffolds are manufactured in Rahaman’s lab through a process known as robocasting – a computer-controlled technique to manufacture materials from ceramic slurries, layer by layer – to ensure uniform structure for the porous material.

In previous studies by the Missouri S&T researchers, porous scaffolds of the silicate glass, known as 13-93, were found to have the same strength properties as cortical bone. Cortical bones are those outer bones of the body that bear the most weight and undergo the most repetitive stress. They include the long bones of the arms and legs.

But what Rahaman and his colleagues didn’t know was how well the silicate 13-93 bioactive glass scaffolds would integrate with bone or how quickly bone would grow into the scaffolding.

“You can have the strongest material in the world, but it also must encourage bone growth in a reasonable amount of time,” says Rahaman. He considers three to six months to be a reasonable time frame for completely regenerating an injured bone into one strong enough to bear weight.

In their studies, the S&T researchers found that the bioactive glass scaffolds bonded quickly to bone and promoted a significant amount of new bone growth within six weeks.

While the skullcap is not a load-bearing bone, it is primarily a cortical bone. The purpose of this research was to demonstrate how well this type of glass scaffolding – already shown to be strong – would interact with cortical bone.

Rahaman and his fellow researchers in the Center for Biomedical Science and Engineering are now experimenting with true load-bearing bones. They are now testing the silicate 13-93 implants in the femurs (leg bones) of laboratory rats.

In the future, Rahaman plans to experiment with modified glass scaffolds to see how well they enhance certain attributes within bone. For instance, doping the glass with copper should promote the growth of blood vessels or capillaries within the new bone, while doping the glass with silver will give it antibacterial properties.

It’s exciting work but they are years from human clinical trials. Still, for those who want to explore further, here’s a link to and a citation for the published paper,

Enhanced bone regeneration in rat calvarial defects implanted with surface-modified and BMP-loaded bioactive glass (13-93) scaffolds by Xin Liua, Mohamed N. Rahaman, Yongxing Liu, B. Sonny Bal, and Lynda F. Bonewald. Acta Biomaterialia, July 2013 issue (Volume 9, Issue 7)  http://dx.doi.org/10.1016/j.actbio.2013.03.039

This paper is behind a paywall.

Caution and nanoscale zinc oxide in sunscreens

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While I’ve had my reservations about the anti-nanoscreen campaigning, it is important to remember that safety research into the use of nanoparticles in sunscreens is ongoing. A new piece of research on nanoscale zinc oxide and sunscreens has been performed at the Missouri University of Science and Technology and this is something I would put under the category of interesting, possibly disturbing, and not at all definitive.

From the May 8, 2012 news item on Nanowerk,

… researchers at Missouri University of Science and Technology are discovering that sunscreen may not be so safe after all. Cell toxicity studies by Dr. Yinfa Ma, Curators’ Teaching Professor of chemistry at Missouri S&T, and his graduate student Qingbo Yang, suggest that when exposed to sunlight, zinc oxide, a common ingredient in sunscreens, undergoes a chemical reaction that may release unstable molecules known as free radicals. Free radicals seek to bond with other molecules, but in the process, they can damage cells or the DNA contained within those cells. This in turn could increase the risk of skin cancer.

…

“Zinc oxide may generate free radicals when exposed to UV (ultraviolet) sunlight,” May [sic] says, “and those free radicals can kill cells.”

Ma studied how human lung cells immersed in a solution containing nano-particles of zinc oxide react when exposed to different types of light over numerous time frames. Using a control group of cells that were not immersed in the zinc oxide solution, Ma compared the results of light exposure on the various groups of cells. He found that zinc oxide-exposed cells deteriorated more rapidly than those not immersed in the chemical compound. Even when exposed to visible light only, the lung cells suspended in zinc oxide deteriorated. But for cells exposed to ultraviolet rays, Ma found that “cell viability decreases dramatically.”

I categorized this research as mildly disturbing for a couple of reasons. (a) It’s never good to hear about lung cells deteriorating. (b) I never slather sunscreen on my lungs. (c) Why didn’t the researcher test skin cells? (d) The cells were immersed in a solution; what concentration of zinc oxide nanoparticles were present in the solution and is that the same concentration found in my sunscreen?

As the researcher notes this work is just part of a longer scientific inquiry (from the May 8, 2012 news item),

Ma’s research on zinc oxide’s effect on cells is still in the early stages, so he cautions people from drawing conclusions about the safety or dangers of sunscreen based on this preliminary research.

“More extensive study is still needed,” May says. “This is just the first step.”

For instance, Ma plans to conduct electron spin resonance tests to see whether zinc oxide truly does generate free radicals, as he suspects. In addition, clinical trials will be needed before any conclusive evidence may be drawn from his studies.

In the meantime, Ma advises sunbathers to use sunscreen and to limit their exposure to the sun.

“I still would advise people to wear sunscreen,” he says. “Sunscreen is better than no protection at all.”

I suspect that last comment is an indirect reference to a recent study (mentioned in my Feb. 9, 2012 posting) that found 13% of Australians said they weren’t using any sunscreens due to their fears about nanoparticles in those products.

At this point, nanosunscreens get a very cautious pass given the information at hand.

For anyone who’s interested in how stories about science and risk, specifically concerning nanosunscreens, can get reported, I’d advise a glance at the 2020 Science blog. (Andrew Maynard, Director of the Risk Science Center at the University of Michigan, has been writing on his 2020 blog for years and covered nanosunscreens on more than one occasion.) In his May 3, 2012 posting he recounts his experience trying to refine comments about nanosunscreens and safety as a reporter is getting his story, with quotes from Andrew, to press.

ETA Aug. 17, 2012: I’d forgotten but was recently reminded that lung cells and skin cells are the same base cell until they differentiate themselves at a later stage of development. (I’m sure scientists are silently screaming but that’s my best description of the process.) So, I better appreciate why the researchers used lung cells for their study but my comment remains, I don’t slather sunscreen on my lungs. While the results of the study are interesting, they don’t seem applicable to a real world experience.