Tag Archives: ACS 248th meeting

Shape-shifting bone material

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Mammals of all kind have a horror disfigurement and will avoid members of their group who are disfigured. This horror is one of the themes to be found in the novel Frankenstein by Mary Shelley. Despite the difficulties, Roger Ebert (film critic) continued to make public appearances after cancer surgeries that changed his appearance (from a June 27, 2012 article by Ronni Gordon for Cancer Today),

Facing the Critics
Roger Ebert finds peace with his appearance following disfiguring cancer surgery

“Today I look like an exhibit in the Texas Chainsaw Museum,” he muses in his 2011 memoir, Life Itself. But Ebert decided he wasn’t going to hide the way he looks. In 2007, before attending his annual Overlooked Film Festival, now referred to as Ebertfest, at the University of Illinois at Urbana-Champaign, Ebert and his wife, Chaz, decided that a photograph of him should accompany a story he wrote for the Sun-Times. Later, he posed for a full-page photo that appeared in Esquire in March 2010.

“No point in denying it,” he wrote about his appearance in Life Itself. “No way to hide it. Better for it to be out there.”

Given the difficulties most people experience, researchers are eager to find solutions. An Aug. 13, 2014 American Chemical Society (ACS) news release (also on EurekAlert) describes a presentation at the ACS 284h meeting about shape-shifting material that could be used to ameliorate bone defects,

Injuries, birth defects (such as cleft palates) or surgery to remove a tumor can create gaps in bone that are too large to heal naturally. And when they occur in the head, face or jaw, these bone defects can dramatically alter a person’s appearance. Researchers will report today that they have developed a “self-fitting” material that expands with warm salt water to precisely fill bone defects, and also acts as a scaffold for new bone growth.

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Currently, the most common method for filling bone defects in the head, face or jaw (known as the cranio-maxillofacial area) is autografting. That is a process in which surgeons harvest bone from elsewhere in the body, such as the hip bone, and then try to shape it to fit the bone defect.

“The problem is that the autograft is a rigid material that is very difficult to shape into these irregular defects,” says Melissa Grunlan, Ph.D., leader of the study. Also, harvesting bone for the autograft can itself create complications at the place where the bone was taken.

Another approach is to use bone putty or cement to plug gaps. However, these materials aren’t ideal. They become very brittle when they harden, and they lack pores, or small holes, that would allow new bone cells to move in and rebuild the damaged tissue.

To develop a better material, Grunlan and her colleagues at Texas A&M University made a shape-memory polymer (SMP) that molds itself precisely to the shape of the bone defect without being brittle. It also supports the growth of new bone tissue.

SMPs are materials whose geometry changes in response to heat. The team made a porous SMP foam by linking together molecules of poly(ε-caprolactone), an elastic, biodegradable substance that is already used in some medical implants. The resulting material resembled a stiff sponge, with many interconnected pores to allow bone cells to migrate in and grow.

Upon heating to 140 degrees Fahrenheit, the SMP becomes very soft and malleable. So, during surgery to repair a bone defect, a surgeon could warm the SMP to that temperature and fill in the defect with the softened material. Then, as the SMP is cooled to body temperature (98.6 degrees Fahrenheit), it would resume its former stiff texture and “lock” into place.

The researchers also coated the SMPs with polydopamine, a sticky substance that helps lock the polymer into place by inducing formation of a mineral that is found in bone. It may also help osteoblasts, the cells that produce bone, to adhere and spread throughout the polymer. The SMP is biodegradable, so that eventually the scaffold will disappear, leaving only new bone tissue behind.

To test whether the SMP scaffold could support bone cell growth, the researchers seeded the polymer with human osteoblasts. After three days, the polydopamine-coated SMPs had grown about five times more osteoblasts than those without a coating. Furthermore, the osteoblasts produced more of the two proteins, runX2 and osteopontin, that are critical for new bone formation.

Grunlan says that the next step will be to test the SMP’s ability to heal cranio-maxillofacial bone defects in animals. “The work we’ve done in vitro is very encouraging,” she says. “Now we’d like to move this into preclinical and, hopefully, clinical studies.”

The researchers acknowledge funding from the Texas A&M Engineering Experiment Station.

It sounds like there’s still quite a long way to go before this research makes its way out of the laboratory. I wish the researchers all the best.

A tattoo that’s a biobattery and a sensor?

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It’s going to be an American Chemical Society (ACS) 248th meeting kind of week as yet another interesting piece of scientific research is bruited (spread) about the internet. This time it’s all about sweat, exercise, and biobatteries. From an Aug. 13, 2014 news item on Nanowerk,

In the future, working up a sweat by exercising may not only be good for your health, but it could also power your small electronic devices. Researchers will report today that they have designed a sensor in the form of a temporary tattoo that can both monitor a person’s progress during exercise and produce power from their perspiration.

An Aug. 13, 2014 ACS news release on EurekAlert, which originated the news item, describes the inspiration (as opposed to perspiration) for this technology,

The device works by detecting and responding to lactate, which is naturally present in sweat. “Lactate is a very important indicator of how you are doing during exercise,” says Wenzhao Jia, Ph.D.

In general, the more intense the exercise, the more lactate the body produces. During strenuous physical activity, the body needs to generate more energy, so it activates a process called glycolysis. Glycolysis produces energy and lactate, the latter of which scientists can detect in the blood.

Professional athletes monitor their lactate levels during performance testing as a way to evaluate their fitness and training program. In addition, doctors measure lactate during exercise testing of patients for conditions marked by abnormally high lactate levels, such as heart or lung disease. Currently, lactate testing is inconvenient and intrusive because blood samples must be collected from the person at different times during the exercise regime and then analyzed.

The news release goes on to describe the research process which resulted in a temporary tattoo that could be used to power small scale electronics,

Jia, a postdoctoral student in the lab of Joseph Wang, D.Sc., at the University of California San Diego, and her colleagues developed a faster, easier and more comfortable way to measure lactate during exercise. They imprinted a flexible lactate sensor onto temporary tattoo paper. The sensor contained an enzyme that strips electrons from lactate, generating a weak electrical current. The researchers applied the tattoo to the upper arms of 10 healthy volunteers. Then the team measured the electrical current produced as the volunteers exercised at increasing resistance levels on a stationary bicycle for 30 minutes. In this way, they could continuously monitor sweat lactate levels over time and with changes in exercise intensity.

The team then went a step further, building on these findings to make a sweat-powered biobattery. Batteries produce energy by passing current, in the form of electrons, from an anode to a cathode. In this case, the anode contained the enzyme that removes electrons from lactate, and the cathode contained a molecule that accepts the electrons.

When 15 volunteers wore the tattoo biobatteries while exercising on a stationary bike, they produced different amounts of power. Interestingly, people who were less fit (exercising fewer than once a week) produced more power than those who were moderately fit (exercising one to three times per week). Enthusiasts who worked out more than three times per week produced the least amount of power. The researchers say that this is probably because the less-fit people became fatigued sooner, causing glycolysis to kick in earlier, forming more lactate. The maximum amount of energy produced by a person in the low-fitness group was 70 microWatts per cm2 of skin.

“The current produced is not that high, but we are working on enhancing it so that eventually we could power some small electronic devices,” Jia says. “Right now, we can get a maximum of 70 microWatts per cm2, but our electrodes are only 2 by 3 millimeters in size and generate about 4 microWatts — a bit small to generate enough power to run a watch, for example, which requires at least 10 microWatts. So besides working to get higher power, we also need to leverage electronics to store the generated current and make it sufficient for these requirements.”

Biobatteries offer certain advantages over conventional batteries: They recharge more quickly, use renewable energy sources (in this case, sweat), and are safer because they do not explode or leak toxic chemicals.

“These represent the first examples of epidermal electrochemical biosensing and biofuel cells that could potentially be used for a wide range of future applications,” Wang says.

The ACS has made a video about this work available,

It seems to me this tattoo battery could be used as a self-powered monitoring device in a medical application for heart or lung disease.

Hemp as a substitute for graphene in supercapacitors

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As a member of the Cannabis plant family, hemp has an undeserved reputation due to its cousin’s (marijuana) notoriety and consciousness-altering properties. Hemp is, by contrast, the Puritan in the family, associated by the knowledgeable with virtues of thrift and hard work.

An Aug. 12, 2014 news item on Nanowerk highlights a hemp/supercapacitor presentation at the 248th meeting of the American Chemical Society (ACS),

As hemp makes a comeback in the U.S. after a decades-long ban on its cultivation, scientists are reporting that fibers from the plant can pack as much energy and power as graphene, long-touted as the model material for supercapacitors. They’re presenting their research, which a Canadian start-up company is working on scaling up, at the 248th National Meeting & Exposition of the American Chemical Society (ACS), the world’s largest scientific society.

David Mitlin, Ph.D., explains that supercapacitors are energy storage devices that have huge potential to transform the way future electronics are powered. Unlike today’s rechargeable batteries, which sip up energy over several hours, supercapacitors can charge and discharge within seconds. But they normally can’t store nearly as much energy as batteries, an important property known as energy density. One approach researchers are taking to boost supercapacitors’ energy density is to design better electrodes. Mitlin’s team has figured out how to make them from certain hemp fibers — and they can hold as much energy as the current top contender: graphene.

An Aug. 12, 2014 ACS news release features David Mitlin, formerly of the University of Alberta (Canada) where this research took place,, Mitlin is now with now with Clarkson University in New York,

“Our device’s electrochemical performance is on par with or better than graphene-based devices,” Mitlin says. “The key advantage is that our electrodes are made from biowaste using a simple process, and therefore, are much cheaper than graphene.”

The race toward the ideal supercapacitor has largely focused on graphene — a strong, light material made of atom-thick layers of carbon, which when stacked, can be made into electrodes. Scientists are investigating how they can take advantage of graphene’s unique properties to build better solar cells, water filtration systems, touch-screen technology, as well as batteries and supercapacitors. The problem is it’s expensive.

Mitlin’s group decided to see if they could make graphene-like carbons from hemp bast fibers. The fibers come from the inner bark of the plant and often are discarded from Canada’s fast-growing industries that use hemp for clothing, construction materials and other products. …

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His team found that if they heated the fibers for 24 hours at a little over 350 degrees Fahrenheit, and then blasted the resulting material with more intense heat, it would exfoliate into carbon nanosheets.

Mitlin’s team built their supercapacitors using the hemp-derived carbons as electrodes and an ionic liquid as the electrolyte. Fully assembled, the devices performed far better than commercial supercapacitors in both energy density and the range of temperatures over which they can work. The hemp-based devices yielded energy densities as high as 12 Watt-hours per kilogram, two to three times higher than commercial counterparts. They also operate over an impressive temperature range, from freezing to more than 200 degrees Fahrenheit.

“We’re past the proof-of-principle stage for the fully functional supercapacitor,” he says. “Now we’re gearing up for small-scale manufacturing.”

I have not been able to confirm the name for Mitlin’s startup but I think it’s called Alta Supercaps (Alta being an abbreviation for Alberta,, amongst other things, and supercaps for supercapacitors) as per the information about a new startup on the Mitlin Group webspace (scroll down to the July 2, 2013 news item) which can still be found on the University of Alberta website (as of Aug. 12, 2014).

For those who would like more technical details, there is this July 2013 article by Mark Crawford for the ASME (American Society of Mechanical Engineers); Note: A link has been removed.

Activated carbons, templated carbons, carbon nanofibers, carbon nanotubes, and graphene have all been intensively studied as materials for supercapacitor electrodes. High manufacturing costs is one issue—another is that the power characteristics of many of these carbons are limited. This is a result of high microporosity, which increases ion transport limitations.

“It is becoming well understood that the key to achieving high power in porous electrodes is to reduce the ion transport limitations” says Mitlin. “Nanomaterials based on graphene and their hybrids have emerged as a new class of promising high-rate electrode candidates—they are, however, too expensive to manufacture compared to activated carbons derived from pyrolysis of agricultural wastes, or from the coking operations.”

Biomass, which mainly contains cellulose and lignin by-products, is widely utilized as a feedstock for producing activated carbons. Mitlin decided to test hemp bast fiber’s unique cellular structure to see if it could produce graphene-like carbon nanosheets.

Hemp fiber waste was pressure-cooked (hydrothermal synthesis) at 180 °C for 24 hours. The resulting carbonized material was treated with potassium hydroxide and then heated to temperatures as high as 800 °C, resulting in the formation of uniquely structured nanosheets. Testing of this material revealed that it discharged 49 kW of power per kg of material—nearly triple what standard commercial electrodes supply, 17 kW/kg.

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Mitlin and his team successfully synthesized two-dimensional, yet interconnected, carbon nanosheets with superior electrochemical storage properties comparable to those of state-of-the-art graphene-based electrodes. “We were able to achieve this by employing a biomass precursor with a unique structure—hemp bast fiber,” says Mitlin. “The resultant graphene-like nanosheets possess fundamentally different properties—such as pore size distribution, physical interconnectedness, and electrical conductivity—as compared to conventional biomass-derived activated carbons.”

This image from Wikimedia was used to illustrate the Crawford article,

Hemp bast fiber is a low-cost graphene-like nanomaterial. Image: Wikimedia Commons

Hemp bast fiber is a low-cost graphene-like nanomaterial. Image: Wikimedia Commons

It seems to me that over the last few months there have been more than the usual number of supercapacitor stories, which makes the race to create the one that will break through in the marketplace fascinating to observe.

Cyborgs (a presentation) at the American Chemical Society’s 248th meeting

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There will be a plethora of chemistry news online over the next few days as the American Society’s (ACS) 248th meeting in San Francisco, CA from Aug. 10 -14, 2014 takes place. Unexpectedly, an Aug. 11, 2014 news item on Azonano highlights a meeting presentation focused on cyborgs,

No longer just fantastical fodder for sci-fi buffs, cyborg technology is bringing us tangible progress toward real-life electronic skin, prosthetics and ultraflexible circuits. Now taking this human-machine concept to an unprecedented level, pioneering scientists are working on the seamless marriage between electronics and brain signaling with the potential to transform our understanding of how the brain works — and how to treat its most devastating diseases.

An Aug. 10, 2014 ACS news release on EurekAlert provides more detail about the presentation (Note: Links have been removed),

“By focusing on the nanoelectronic connections between cells, we can do things no one has done before,” says Charles M. Lieber, Ph.D. “We’re really going into a new size regime for not only the device that records or stimulates cellular activity, but also for the whole circuit. We can make it really look and behave like smart, soft biological material, and integrate it with cells and cellular networks at the whole-tissue level. This could get around a lot of serious health problems in neurodegenerative diseases in the future.”

These disorders, such as Parkinson’s, that involve malfunctioning nerve cells can lead to difficulty with the most mundane and essential movements that most of us take for granted: walking, talking, eating and swallowing.

Scientists are working furiously to get to the bottom of neurological disorders. But they involve the body’s most complex organ — the brain — which is largely inaccessible to detailed, real-time scrutiny. This inability to see what’s happening in the body’s command center hinders the development of effective treatments for diseases that stem from it.

By using nanoelectronics, it could become possible for scientists to peer for the first time inside cells, see what’s going wrong in real time and ideally set them on a functional path again.

For the past several years, Lieber has been working to dramatically shrink cyborg science to a level that’s thousands of times smaller and more flexible than other bioelectronic research efforts. His team has made ultrathin nanowires that can monitor and influence what goes on inside cells. Using these wires, they have built ultraflexible, 3-D mesh scaffolding with hundreds of addressable electronic units, and they have grown living tissue on it. They have also developed the tiniest electronic probe ever that can record even the fastest signaling between cells.

Rapid-fire cell signaling controls all of the body’s movements, including breathing and swallowing, which are affected in some neurodegenerative diseases. And it’s at this level where the promise of Lieber’s most recent work enters the picture.

In one of the lab’s latest directions, Lieber’s team is figuring out how to inject their tiny, ultraflexible electronics into the brain and allow them to become fully integrated with the existing biological web of neurons. They’re currently in the early stages of the project and are working with rat models.

“It’s hard to say where this work will take us,” he says. “But in the end, I believe our unique approach will take us on a path to do something really revolutionary.”

Lieber acknowledges funding from the U.S. Department of Defense, the National Institutes of Health and the U.S. Air Force.

I first covered Lieber’s work in an Aug. 27, 2012 posting  highlighting some good descriptions from Lieber and his colleagues of their work. There’s also this Aug. 26, 2012 article by Peter Reuell in the Harvard Gazette (featuring a very good technical description for someone not terribly familiar with the field but able to grasp some technical information while managing their own [mine] ignorance). The posting and the article provide details about the foundational work for Lieber’s 2014 presentation at the ACS meeting.

Lieber will be speaking next at the IEEE (Institute for Electrical and Electronics Engineers) 14th International Conference on Nanotechnology sometime between August 18 – 21, 2014 in Toronto, Ontario, Canada.

As for some of Lieber’s latest published work, there’s more information in my Feb. 20, 2014 posting which features a link to a citation for the paper (behind a paywall) in question.