Researchers at Oregon State University reach Milestone in use of Nanoparticles to kill Cancer with Heat

Abstract:
Researchers at Oregon State University have developed an improved technique for using magnetic nanoclusters to kill hard-to-reach tumors.

 

Magnetic nanoparticles – tiny pieces of matter as small as one-billionth of a meter – have shown anti-cancer promise for tumors easily accessible by syringe, allowing the particles to be injected directly into the cancerous growth.

Once injected into the tumor, the nanoparticles are exposed to an alternating magnetic field, or AMF. This field causes the nanoparticles to reach temperatures in excess of 100 degrees Fahrenheit, which causes the cancer cells to die.

But for some cancer types such as prostate cancer, or the ovarian cancer used in the Oregon State study, direct injection is difficult. In those types of cases, a “systemic” delivery method – intravenous injection, or injection into the abdominal cavity – would be easier and more effective.

The challenge for researchers has been finding the right kind of nanoparticles – ones that, when administered systemically in clinically appropriate doses, accumulate in the tumor well enough to allow the AMF to heat cancer cells to death.

Olena Taratula and Oleh Taratula of the OSU College of Pharmacy tackled the problem by developing nanoclusters, multiatom collections of nanoparticles, with enhanced heating efficiency. The nanoclusters are hexagon-shaped iron oxide nanoparticles doped with cobalt and manganese and loaded into biodegradable nanocarriers.

Findings were published in ACS Nano.

“There had been many attempts to develop nanoparticles that could be administered systemically in safe doses and still allow for hot enough temperatures inside the tumor,” said Olena Taratula, associate professor of pharmaceutical sciences. “Our new nanoplatform is a milestone for treating difficult-to-access tumors with magnetic hyperthermia. This is a proof of concept, and the nanoclusters could potentially be optimized for even greater heating efficiency.”

The nanoclusters’ ability to reach therapeutically relevant temperatures in tumors following a single, low-dose IV injection opens the door to exploiting the full potential of magnetic hyperthermia in treating cancer, either by itself or with other therapies, she added.

“It’s already been shown that magnetic hyperthermia at moderate temperatures increases the susceptibility of cancer cells to chemotherapy, radiation and immunotherapy,” Taratula said.

The mouse model in this research involved animals receiving IV nanocluster injections after ovarian tumors had been grafted underneath their skin.

“To advance this technology, future studies need to use orthotopic animal models – models where deep-seated tumors are studied in the location they would actually occur in the body,” she said. “In addition, to minimize the heating of healthy tissue, current AMF systems need to be optimized, or new ones developed.”

The National Institutes of Health, the OSU College of Pharmacy and Najran University of Saudi Arabia supported this research.

Also collaborating were OSU electrical engineering professor Pallavi Dhagat, postdoctoral scholars Xiaoning Li and Canan Schumann of the College of Pharmacy, pharmacy graduate students Hassan Albarqi, Fahad Sabei and Abraham Moses, engineering graduate student Mikkel Hansen, and pre-pharmacy undergrads Tetiana Korzun and Leon Wong.

Copyright © Oregon State University

Chemists could make ‘smart glass’ smarter by manipulating it at the nanoscale: Colorado State University

Chemists have devised a potentially major improvement to both the speed and durability of smart glass by providing a better understanding of how the glass works at the nanoscale.

An alternative nanoscale design for eco-friendly smart glass

Source: Colorado State University

“Smart glass,” an energy-efficiency product found in newer windows of cars, buildings and airplanes, slowly changes between transparent and tinted at the flip of a switch.

“Slowly” is the operative word; typical smart glass takes several minutes to reach its darkened state, and many cycles between light and dark tend to degrade the tinting quality over time. Colorado State University chemists have devised a potentially major improvement to both the speed and durability of smart glass by providing a better understanding of how the glass works at the nanoscale.

They offer an alternative nanoscale design for smart glass in new research published June 3 in Proceedings of the National Academy of Sciences. The project started as a grant-writing exercise for graduate student and first author R. Colby Evans, whose idea — and passion for the chemistry of color-changing materials — turned into an experiment involving two types of microscopy and enlisting several collaborators. Evans is advised by Justin Sambur, assistant professor in the Department of Chemistry, who is the paper’s senior author.

The smart glass that Evans and colleagues studied is “electrochromic,” which works by using a voltage to drive lithium ions into and out of thin, clear films of a material called tungsten oxide. “You can think of it as a battery you can see through,” Evans said. Typical tungsten-oxide smart glass panels take 7-12 minutes to transition between clear and tinted.

The researchers specifically studied electrochromic tungsten-oxide nanoparticles, which are 100 times smaller than the width of a human hair. Their experiments revealed that single nanoparticles, by themselves, tint four times faster than films of the same nanoparticles. That’s because interfaces between nanoparticles trap lithium ions, slowing down tinting behavior. Over time, these ion traps also degrade the material’s performance.

To support their claims, the researchers used bright field transmission microscopy to observe how tungsten-oxide nanoparticles absorb and scatter light. Making sample “smart glass,” they varied how much nanoparticle material they placed in their samples and watched how the tinting behaviors changed as more and more nanoparticles came into contact with each other. They then used scanning electron microscopy to obtain higher-resolution images of the length, width and spacing of the nanoparticles, so they could tell, for example, how many particles were clustered together, and how many were spread apart.

Based on their experimental findings, the authors proposed that the performance of smart glass could be improved by making a nanoparticle-based material with optimally spaced particles, to avoid ion-trapping interfaces.

Their imaging technique offers a new method for correlating nanoparticle structure and electrochromic properties; improvement of smart window performance is just one application that could result. Their approach could also guide applied research in batteries, fuel cells, capacitors and sensors.

“Thanks to Colby’s work, we have developed a new way to study chemical reactions in nanoparticles, and I expect that we will leverage this new tool to study underlying processes in a wide range of important energy technologies,” Sambur said.

The paper’s co-authors include Austin Ellingworth, a former Research Experience for Undergraduates student from Winona State University; Christina Cashen, a CSU chemistry graduate student; and Christopher R. Weinberger, a professor in CSU’s Department of Mechanical Engineering

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Story Source:

Materials provided by Colorado State University. Original written by Anne Manning. Note: Content may be edited for style and length.

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Journal Reference:

1. R. Colby Evans, Austin Ellingworth, Christina J. Cashen, Christopher R. Weinberger, Justin B. Sambur. Influence of single-nanoparticle electrochromic dynamics on the durability and speed of smart windows. Proceedings of the National Academy of Sciences, 2019; 201822007 DOI: 10.1073/pnas.1822007116

 

Colorado State University. “Chemists could make ‘smart glass’ smarter by manipulating it at the nanoscale: An alternative nanoscale design for eco-friendly smart glass.” ScienceDaily. ScienceDaily, 4 June 2019. <www.sciencedaily.com/releases/2019/06/190604131210.htm>.

MIT: A better way to encapsulate islet cells for Diabetes Treatment – Prevents immune system Rejection of transplanted Pancreatic Islet Cells

 

MIT engineers have devised a way to incorporate crystallized immunosuppressant drugs into devices carrying encapsulated islet cells, which could allow them to be implanted as a long-term 

 

Crystallized drug prevents immune system rejection of transplanted pancreatic islet cells.

 

When medical devices are implanted in the body, the immune system often attacks them, producing scar tissue around the device. This buildup of tissue, known as fibrosis, can interfere with the device’s function.

MIT researchers have now come up with a novel way to prevent fibrosis from occurring, by incorporating a crystallized immunosuppressant drug into devices. After implantation, the drug is slowly secreted to dampen the immune response in the area immediately surrounding the device.

“We developed a crystallized drug formulation that can target the key players involved in the implant rejection, suppressing them locally and allowing the device to function for more than a year,” says Shady Farah, an MIT and Boston Children’s Hospital postdoc and co-first author of the study, who is soon starting a new position as an assistant professor of the Wolfson Faculty of Chemical Engineering and the Russell Berrie Nanotechnology Institute at Technion-Israel Institute of Technology.

The researchers showed that these crystals could dramatically improve the performance of encapsulated islet cells, which they are developing as a possible treatment for patients with type 1 diabetes. Such crystals could also be applied to a variety of other implantable medical devices, such as pacemakers, stents, or sensors.

Former MIT postdoc Joshua Doloff, now an assistant professor of Biomedical and Materials Science Engineering and member of the Translational Tissue Engineering Center at Johns Hopkins University School of Medicine, is also a lead author of the paper, which appears in the June 24 issue of Nature Materials. Daniel Anderson, an associate professor in MIT’s Department of Chemical Engineering and a member of MIT’s Koch Institute for Integrative Cancer Research and Institute for Medical Engineering and Science (IMES), is the senior author of the paper.

Crystalline drug

Anderson’s lab is one of many research groups working on ways to encapsulate islet cells and transplant them into diabetic patients, in hopes that such cells could replace the patients’ nonfunctioning pancreatic cells and eliminate the need for daily insulin injections.

Fibrosis is a major obstacle to this approach, because scar tissue can block the islet cells’ access to the oxygen and nutrients. In a 2017 study, Anderson and his colleagues showed that systemic administration of a drug that blocks cell receptors for a protein called CSF-1 can prevent fibrosis by suppressing the immune response to implanted devices. This drug targets immune cells called macrophages, which are the primary cells responsible for initiating the inflammation that leads to fibrosis.

“That work was focused on identifying next-generation drug targets, namely which cell and cytokine players were essential for fibrotic response,” says Doloff, who was the lead author on that study, which also involved Farah. He adds, “After knowing what we had to target to block fibrosis, and screening drug candidates needed to do so, we still had to find a sophisticated way of achieving local delivery and release for as long as possible.”

In the new study, the researchers set out to find a way to load the drug directly into an implantable device, to avoid giving patients drugs that would suppress their entire immune system.

“If you have a small device implanted in your body, you don’t want to have your whole body exposed to drugs that are affecting the immune system, and that’s why we’ve been interested in creating ways to release drugs from the device itself,” Anderson says.

To achieve that, the researchers decided to try crystallizing the drugs and then incorporating them into the device. This allows the drug molecules to be very tightly packed, allowing the drug-releasing device to be miniaturized. Another advantage is that crystals take a long time to dissolve, allowing for long-term drug delivery. Not every drug can be easily crystallized, but the researchers found that the CSF-1 receptor inhibitor they were using can form crystals and that they could control the size and shape of the crystals, which determines how long it takes for the drug to break down once in the body.

“We showed that the drugs released very slowly and in a controlled fashion,” says Farah. “We took those crystals and put them in different types of devices and showed that with the help of those crystals, we can allow the medical device to be protected for a long time, allowing the device to keep functioning.”

Encapsulated islet cells

To test whether these drug crystalline formulations could boost the effectiveness of encapsulated islet cells, the researchers incorporated the drug crystals into 0.5-millimeter-diameter spheres of alginate, which they used to encapsulate the cells. When these spheres were transplanted into the abdomen or under the skin of diabetic mice, they remained fibrosis-free for more than a year. During this time, the mice did not need any insulin injections, as the islet cells were able to control their blood sugar levels just as the pancreas normally would.

“In the past three-plus years, our team has published seven papers in Nature journals — this being the seventh — elucidating the mechanisms of biocompatibility,” says Robert Langer, the David H. Koch Institute Professor at MIT and an author of the paper. “These include an understanding of the key cells and receptors involved, optimal implant geometries and physical locations in the body, and now, in this paper, specific molecules that can confer biocompatibility. Taken together, we hope these papers will open the door to a new generation of biomedical implants to treat diabetes and other diseases.”

The researchers believe that it should be possible to create crystals that last longer than those they studied in these experiments, by altering the structure and composition of the drug crystals. Such formulations could also be used to prevent fibrosis of other types of implantable devices. In this study, the researchers showed that crystalline drug could be incorporated into PDMS, a polymer frequently used for medical devices, and could also be used to coat components of a glucose sensor and an electrical muscle stimulation device, which include materials such as plastic and metal.

“It wasn’t just useful for our islet cell therapy, but could also be useful to help get a number of different devices to work long-term,” Anderson says.

The research was funded by JDRF, the National Institutes of Health, the Leona M. and Harry B. Helmsley Charitable Trust Foundation, and the Tayebati Family Foundation.

Other authors of the paper include MIT Principal Research Scientist Peter Muller; MIT grad students Atieh Sadraei and Malia McAvoy; MIT research affiliate Hye Jung Han; former MIT postdoc Katy Olafson; MIT technical associate Keval Vyas; former MIT grad student Hok Hei Tam; MIT postdoc Piotr Kowalski; former MIT undergraduates Marissa Griffin and Ashley Meng; Jennifer Hollister-Locke and Gordon Weir of the Joslin Diabetes Center; Adam Graham of Harvard University; James McGarrigle and Jose Oberholzer of the University of Illinois at Chicago; and Dale Greiner of the University of Massachusetts Medical School.

Tech Talks: Solar-Enabled Water Treatment for DoD Facilities and Forward Operating Bases

Presented by: Joel Hewett, HDIAC SME

Presented on: May 30th, 2019

Taxonomy: Alternative Energy

Description: 
Protecting the nation from threats at home and abroad requires an assured supply of clean drinking water – and lots of it.

Together with researchers from Washington University in St. Louis, HDIAC Subject Matter Expert Joel Hewett discusses new technologies in development that can help assure an uninterrupted supply of drinking water for those who need it most.

Read More: ‘Nano Enabled Water Treatment or NEWT

NEWT is applying nanotechnology to develop transformative and off-grid water treatment systems that both protect human lives and support sustainable economic development.

Advanced NMR at Ames Lab captures new details in nanoparticle structures – Applications in catalysis, chemical separations, biosensing, and drug delivery

“With possible applications in catalysis, chemical separations, biosensing, and drug delivery, MSNs (mesoporous silica nanoparticles) are the focus of intense scientific research.”

Advanced nuclear magnetic resonance (NMR) techniques at the U.S. Department of Energy’s Ames Laboratory have revealed surprising details about the structure of a key group of materials in nanotechology, mesoporous silica nanoparticles (MSNs), and the placement of their active chemical sites.

MSNs are honeycombed with tiny (about 2-15 nm wide) three-dimensionally ordered tunnels or pores, and serve as supports for organic functional groups tailored to a wide range of needs. With possible applications in catalysis, chemical separations, biosensing, and drug delivery, MSNs are the focus of intense scientific research.

“Since the development of MSNs, people have been trying to control the way they function,” said Takeshi Kobayashi, an NMR scientist with the Division of Chemical and Biological Sciences at Ames Laboratory.

“Research has explored doing this through modifying particle size and shape, pore size, and by deploying various organic functional groups on their surfaces to accomplish the desired chemical tasks. However, understanding of the results of these synthetic efforts can be very challenging.”

Ames Laboratory scientist Marek Pruski explained that despite the existence of different techniques for MSNs’ functionalization, no one knew exactly how they were different. In particular, atomic-scale description of how the organic groups were distributed on the surface was lacking until recently.

“It is one thing to detect and quantify these functional groups, or even determine their structure,” said Pruski. “But elucidating their spatial arrangement poses additional challenges.

Do they reside on the surfaces or are they partly embedded in the silica walls? Are they uniformly distributed on surfaces? If there are multiple types of functionalities, are they randomly mixed or do they form domains?

Conventional NMR, as well as other analytical techniques, have struggled to provide satisfactory answers to these important questions.”

Kobayashi, Pruski, and other researchers used DNP-NMR to obtain a much clearer picture of the structures of functionalized MSNs. “DNP” stands for “dynamic nuclear polarization,” a method which uses microwaves to excite unpaired electrons in radicals and transfer their high spin polarization to the nuclei in the sample being analyzed, offering drastically higher sensitivity, often by two orders of magnitude, and even larger savings of experimental time.

Conventional NMR, which measures the responses of the nuclei of atoms placed in a magnetic field to direct radio-frequency excitation, lacks the sensitivity needed to identify the internuclear interactions between different sites and functionalities on surfaces.

When paired with DNP, as well as fast magic angle spinning (MAS), NMR can be used to detect such interactions with unprecedented sensitivity.

Not only did the DNP-NMR methods elicit the atomic-scale location and distribution of the functional groups, but the results disproved some of the existing notions of how MSNs are made and how the different synthetic strategies influenced the dispersion of functional groups throughout the silica pores.

“By examining the role of various experimental conditions, our NMR techniques can give scientists the mechanistic insight they need to guide the synthesis of MSNs in a more controlled way,” said Kobayashi.

The research is further discussed in “Spatial distribution of silica-bound catalytic organic functional groups can now be revealed by conventional and DNP-enhanced solid-state NMR methods,” authored by T. Kobayashi and M. Pruski; and published in ACS Catalysis.

Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

The U.S. Department of Energy’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States and is working to address some of the most pressing challenges of our time. For more information, visit https://energy.gov/science.

Lawrence Berkeley National Lab scientists grow spiraling new Crystal material Which could yield unique optical, electronic and thermal properties, including super conductivity SuperChem

UC Berkeley and Berkeley Lab researchers created a new crystal built of a spiraling stack of atomically thin 

UC Berkeley and Berkeley Lab researchers created a new crystal built of a spiraling stack of atomically thin germanium sulfide sheets. Credit: UC Berkeley image by Yin Liu

With a simple twist of the fingers, one can create a beautiful spiral from a deck of cards. In the same way, scientists at the University of California, Berkeley, and Lawrence Berkeley National Laboratory (Berkeley Lab) have created new inorganic crystals made of stacks of atomically thin sheets that unexpectedly spiral like a nanoscale card deck.

Their surprising structures, reported in a new study appearing online Wednesday, June 20, in the journal Nature, may yield unique optical, electronic and thermal properties, including superconductivity, the researchers say.

These helical crystals are made of stacked layers of germanium sulfide, a semiconductor material that, like graphene, readily forms sheets that are only a few atoms or even a single atom thick. Such “nanosheets” are usually referred to as “2-D materials.”

“No one expected 2-D materials to grow in such a way. It’s like a surprise gift,” said Jie Yao, an assistant professor of materials science and engineering at UC Berkeley. “We believe that it may bring great opportunities for materials research.”

While the shape of the crystals may resemble that of DNA, whose helical structure is critical to its job of carrying genetic information, their underlying structure is actually quite different. Unlike “organic” DNA, which is primarily built of familiar atoms like carbon, oxygen and hydrogen, these “inorganic” crystals are built of more far-flung elements of the periodic table—in this case, sulfur and germanium. And while organic molecules often take all sorts of zany shapes, due to unique properties of their primary component, carbon, inorganic molecules tend more toward the straight and narrow.

To create the twisted structures, the team took advantage of a crystal defect called a screw dislocation, a “mistake” in the orderly crystal structure that gives it a bit of a twisting force. This “Eshelby Twist,” named after scientist John D. Eshelby, has been used to create nanowires that spiral like pine trees. But this study is the first time the Eshelby Twist has been used to make crystals built of stacked 2-D layers of an atomically thin semiconductor.

The helical crystals may yield surprising new properties, like superconductivity. Credit: UC Berkeley image by Yin Liu

“Usually, people hate defects in a material—they want to have a perfect crystal,” said Yao, who also serves as a faculty scientist at Berkeley Lab. “But it turns out that, this time, we have to thank the defects. They allowed us to create a natural twist between the material layers.”

In a major discovery last year, scientists reported that graphene becomes superconductive when two atomically thin sheets of the material are stacked and twisted at what’s called a “magic angle.” While other researchers have succeeded at stacking two layers at a time, the new paper provides a recipe for synthesizing stacked structures that are hundreds of thousands or even millions of layers thick in a continuously twisting fashion.

“We observed the formation of discrete steps in the twisted crystal, which transforms the smoothly twisted crystal to circular staircases, a new phenomenon associated with the Eshelby Twist mechanism,” said Yin Liu, co-first author of the paper and a graduate student in materials science and engineering at UC Berkeley. “It’s quite amazing how interplay of materials could result in many different, beautiful geometries.”

By adjusting the material synthesis conditions and length, the researchers could change the angle between the layers, creating a twisted structure that is tight, like a spring, or loose, like an uncoiled Slinky. And while the research team demonstrated the technique by growing helical crystals of germanium sulfide, it could likely be used to grow layers of other materials that form similar atomically thin layers.

“The twisted structure arises from a competition between stored energy and the energy cost of slipping two material layers relative to one another,” said Daryl Chrzan, chair of the Department of Materials Science and Engineering and senior theorist on the paper. “There is no reason to expect that this competition is limited to germanium sulfide, and similar structures should be possible in other 2-D material systems.”

“The twisted behavior of these layered materials, typically with only two layers twisted at different angles, has already showed great potential and attracted a lot of attention from the physics and chemistry communities. Now, it becomes highly intriguing to find out, with all of these twisted layers combined in our new material, if will they show quite different material properties than regular stacking of these materials,” Yao said. “But at this moment, we have very limited understanding of what these properties could be, because this form of material is so new. New opportunities are waiting for us.”

Explore further

Research team discovers perfectly imperfect twist on nanowire growth

 

Graphene-based ink may lead to printable energy storage devices

Top) The salt-templated process of synthesizing graphene nanosheets into ink. (Bottom) The ink and printed demonstration. Credit: Wei et al. ©2019 American Chemical Society

Researchers have created an ink made of graphene nanosheets, and demonstrated that the ink can be used to print 3-D structures. As the graphene-based ink can be mass-produced in an inexpensive and environmentally friendly manner, the new methods pave the way toward developing a wide variety of printable energy storage devices.

The researchers, led by Jingyu Sun and Zhongfan Liu at Soochow University and the Beijing Graphene Institute, and Ya-yun Li at Shenzhen University, have published a paper on their work in a recent issue of ACS Nano.

“Our work realizes the scalable and green synthesis of nitrogen-doped graphene nanosheets on a salt template by direct chemical vapor deposition,” Sun told Phys.org. “This allows us to further explore thus-derived inks in the field of printable energy storage.”

As the scientists explain, a key goal in graphene research is the mass production of graphene with high quality and at low cost. Energy-storage applications typically require graphene in powder form, but so far production methods have resulted in powders with a large number of structural defects and chemical impurities, as well as nonuniform layer thickness. This has made it difficult to prepare high-quality graphene inks.

In the new paper, the researchers have demonstrated a new method for preparing graphene inks that overcomes these challenges. The method involves growing nitrogen-doped graphene nanosheets over NaCl crystals using direct chemical vapor deposition, which causes molecular fragments of nitrogen and carbon to diffuse on the surface of the NaCl crystals. The researchers chose NaCl due to its natural abundance and low cost, as well as its water solubility.

To remove the NaCl, the coated crystals are submerged in water, which causes the NaCl to dissolve and leave behind pure nitrogen-doped graphene cages. In the final step, treating the cages with ultrasound transforms the cages into 2-D nanosheets, each about 5-7 graphite layers thick.

The resulting nitrogen-doped graphene nanosheets have relatively few defects and an ideal size (about 5 micrometers in side length) for printing, as larger flakes can block the nozzle.

To demonstrate the nanosheets’ effectiveness, the researchers printed a wide variety of 3-D structures using inks based on the graphene sheets.

Among their demonstrations, the researchers used the ink as a conductive additive for an electrode material (vanadium nitride) and used the composite ink to print flexible electrodes for supercapacitors with high power density and good cyclic stability. 

In a second demonstration, the researchers created a composite ink made of the graphene sheets along with binder material (polypropylene) for printing interlayers for Li−S batteries.

Compared to batteries with separators made only of the conventional material, those made with the composite material exhibited enhanced conductivity, leading to an overall improvement in battery performance.

“In the future, we plan to exploit the direct chemical vapor depositiontechnique for the mass production of high-quality graphene powders toward emerging printable energy storage applications,” Sun said.

More information: Nan Wei et al. “Scalable Salt-Templated Synthesis of Nitrogen-Doped Graphene Nanosheets toward Printable Energy Storage.” ACS Nano. DOI: 10.1021/acsnano.9b03157

Journal information: ACS Nano

‘Self-healing’ polymer brings perovskite solar tech closer to market

This perovskite solar module is better able to contain the lead within its structure when a layer of epoxy resin is added to its surface. This approach to tackling a long-standing environmental concern helps bring the technology closer to commercialization. Credit: OIST

A protective layer of epoxy resin helps prevent the leakage of pollutants from perovskite solar cells (PSCs), according to scientists from the Okinawa Institute of Science and Technology Graduate University (OIST). Adding a “self-healing” polymer to the top of a PSC can radically reduce how much lead it discharges into the environment. This gives a strong boost to prospects for commercializing the technology.

With atmospheric carbon dioxide levels reaching their highest recorded levels in history, and extreme weather events continuing to rise in number, the world is moving away from legacy energy systems relying on fossil fuels towards renewables such as solar. Perovskite solar technology is promising, but one key challenge to commercialization is that it may release pollutants such as lead into the environment—especially under extreme weather conditions.

“Although PSCs are efficient at converting sunlight into electricity at an affordable cost, the fact that they contain lead raises considerable environmental concern,” explains Professor Yabing Qi, head of the Energy Materials and Surface Sciences Unit, who led the study, published in Nature Energy.

“While so-called ‘lead-free’ technology is worth exploring, it has not yet achieved efficiency and stability comparable to lead-based approaches. Finding ways of using lead in PSCs while keeping it from leaking into the environment, therefore, is a crucial step for commercialization.”

Testing to destruction

Qi’s team, supported by the OIST Technology Development and Innovation Center’s Proof-of-Concept Program, first explored encapsulation methods for adding protective layers to PSCs to understand which materials might best prevent the leakage of lead. They exposed cells encapsulated with different materials to many conditions designed to simulate the sorts of weather to which the cells would be exposed in reality.

They wanted to test the solar cells in a worst-case weather scenario, to understand the maximum lead leakage that could occur. First, they smashed the solar cells using a large ball, mimicking extreme hail that could break down their structure and allow lead to be leaked. Next, they doused the cells with acidic water, to simulate the rainwater that would transport leaked lead into the environment.

Using mass spectroscopy, the team analyzed the acidic rain to determine how much lead leaked from the cells. They found that an epoxy resin layer allowed only minimal lead leakage—orders of magnitude lower than the other materials.

Researchers exposed the solar cells to brutal conditions to simulate worst-case weather scenarios. Adding a self-healing epoxy resin polymer to the cell minimized the leakage of lead from the cell. Credit: OIST

Enabling commercial viability

Epoxy resin also performed best under a number of weather conditions in which sunlight, rainwater and temperature were altered to simulate the environments in which PSCs must operate. In all scenarios, including extreme rain, epoxy resin outperformed rival encapsulation materials.

Epoxy resin works so well due to its “self-healing” properties. After its structure is damaged by hail, for example, the polymer partially reforms its original shape when heated by sunlight. This limits the amount of lead that leaks from inside the cell. This self-healing property could make epoxy resin the encapsulation layer of choice for future photovoltaic products.

“Epoxy resin is certainly a strong candidate, yet other self-healing polymers may be even better,” explains Qi. “At this stage, we are pleased to be promoting photovoltaic industry standards, and bringing the safety of this technology into the discussion. Next, we can build on these data to confirm which is truly the best polymer.”

Beyond lead leakage, another challenge will be to scale up perovskite solar cells into perovskite solar panels. While cells are just a few centimeters long, panels can span a few meters, and will be more relevant to potential consumers. The team will also direct their attention to the long-standing challenge of renewable energy storage.

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Explore further

The potential of non-toxic materials to replace lead in perovskite solar cells

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More information: Reduction of lead leakage from damaged lead halide perovskite solar modules using self-healing polymer-based encapsulation, Nature Energy (2019). DOI: 10.1038/s41560-019-0406-2, https://www.nature.com/articles/s41560-019-0406-2

Journal information: Nature Energy

COULD TECHNION RESEARCHERS SOLVE THE WORLD’S WATER CRISIS?

 

The World Health Organization (WHO) estimates that by 2025, about half of the world’s population will live in areas where there is a shortage of clean drinking water. Is it possible that the solution to the global water crisis is, literally, right under our noses? Technion researchers have developed a model for a system that separates the moisture naturally present in the air around us and converts it into drinking water. The patented system, and how it can help prevent the water crisis that awaits the world, was recently presented by Associate Professor David Broday of Technion’s Faculty of Civil and Environmental Engineering at a seminar on water, energy, treatment, and recycling.

“Water is available and free to everyone”

Associate Professor Broday, who developed the system together with his colleague Associate Professor Eran Friedler, explains that the idea is to take advantage of a resource that is constantly and abundantly present around us.

“The atmosphere is everywhere, and there is humidity everywhere,” says Broday. “No atmosphere is completely dry; there is humidity even in the air of the arid Sahara Desert. In fact, the amount of moisture in the atmosphere is equal to the amount of fresh liquid water in the world (i.e. not accounting for glaciers). This is a huge amount of water freely available to everyone with no restrictions.”

Harvesting moisture from the air is not new, and there are several companies around the world that have already developed technologies around this concept. This existing technology, says Broday, is similar to a domestic air conditioner that cools air that comes from the outdoors, uses the cold air, and discards the water condensed during the cooling process. In the case of moisture harvesting technology, it is the air that is discarded and the water that is used. “The existing technology actually takes air and cools it to extract the moisture from it,” explains Broday. “It is brought to a state where the moisture condenses on a cold surface and drips from it, then it is collected and used for drinking.”

But, says Prof. Broday, there is a problem with this technology. “Air is composed not only of moisture but also of other gases like oxygen and nitrogen, and this technology invests in cooling them along with the humidity,” he explains. “Air volume contains only 4 to 5 percent humidity, at best, which is a very small part. A lot of energy is invested in cooling something of which more than 90 percent doesn’t get used at all. This is an ineffective use of energy. This process is expensive to begin with, and in effect most of the energy goes towards cooling material that we are not at all interested in.”

With their system, the researchers propose to optimize this process by separating moisture from the air before cooling it. Doing so will make it possible to invest energy in cooling only the moisture itself and converting it into available water.

 

Global Maps for ‘Water from Air Resources

 

The Technion system is also a radical departure from attempts by others who are trying to develop membranes that will separate the moisture out of the air (like the desalination process in which membranes separate salt from seawater).

“The alternative we are proposing is based on the use of an absorbent substance called a desiccant, which is a highly concentrated saline solution that naturally absorbs the moisture from the air when it comes into contact with it,” Broday explains. “The idea is to use this material to absorb a large amount of moisture from the air, and to cool the moisture only after this has been accomplished.”

“Our system is composed of several stages,” he explains. “In the first stage, it will circulate air to transfer moisture from the air to the dessicant, which is in a liquid state. This cycle is repeated over and over again, as the dessicant collects more and more moisture from the air. In the second stage, we transfer a small portion of the dessicant to another part of the system, where we produce conditions that cause the desiccant to release the moisture. This moisture is then condensed and turned into water. For this to happen, we need to cool it down – this is the third stage, which is actually similar to what happens in existing systems; but unlike them, at this stage we cool 100 percent humidity rather than air, only a fraction of which is relevant to our needs.”

Drinkable water in the middle of the desert

According to the researchers, their proposed system isn’t just more energy-efficient. It also provides cleaner water. After cooling, the water collected in the system should be suitable for immediate drinking, as opposed to existing technologies in which air is cooled in its entirety. “If the air spinning in a system – in addition to moisture – contains disease-causing bacteria, when it is cooled and the water condenses, the bacteria in the air may also find their way into the water,” Broday explains. “This means this water may require purification to make it fit for consumption.­­­­

“In our system, the air does not meet the cooling coils at all – only the moisture that is separated from it. As a result, even if the air contains substances we do not want to reach the water, they are absorbed into the dessicant but not released in the next stage,” he says. “Even if bacteria, dust, and the like have accumulated, because it is a very concentrated salt solution, it simply dries up. So the resulting moisture would be clean, and the water, pure. Of course they would be tested, but the need for water treatment processes would probably be much smaller, which is expected to lower the price of using it.”

Using the system would not be without cost, and the researchers emphasize that their method of producing water is more expensive than desalination.

“Where water can be desalinated – that is, in proximity to a source of water such as a sea or brackish lakes – desalination is the preferred option,” explains Broday. “Economically speaking, it makes sense to desalinate and produce a system for transporting water to places that are up to about 62 miles away. Any further than this, and the cost of transportation becomes more expensive than the cost of desalination. There are also towns located close to rivers where water is suitable for use. But when we take all of these out of the equation, there are quite a few places in the world where desalination and direct use are not economically viable.”

The Technion researchers’ system has not yet been built, but they have already performed simulations with a model to see how the system would function in different climatic and humidity conditions. “We wanted to see whether the system can be used in areas where the air is arid,” says Broday, “for example in the Sahara Desert, and in Yemen, which is currently experiencing a severe hunger crisis and lack of drinking water.” He says the system is both relatively small and allows for distributed production of water that does not depend on one source from which the water must be piped to all the other localities.

“We strongly believe in the idea and the preliminary results,” says Broday. “But we still have to put the theory into practice. That’s the next stage.”

The Technion-Israel Institute of Technology is a major source of the innovation and brainpower that drives the Israeli economy, and a key to Israel’s renown as the world’s “Start-Up Nation.” Its three Nobel Prize winners exemplify academic excellence. Technion people, ideas and inventions make immeasurable contributions to the world including life-saving medicine, sustainable energy, computer science, water conservation and nanotechnology.

American Technion Society (ATS) donors provide critical support for the Technion—nearly $2.5 billion since its inception in 1940. Based in New York City, the ATS and its network of supporters across the U.S. provide funds for scholarships, fellowships, faculty recruitment and chairs, research, buildings, laboratories, classrooms and dormitories, and more.

Engineers at Rice University boost output of solar desalination system by 50%

Concentrating the sunlight on tiny spots on the heat-generating membrane exploits an inherent and previously unrecognized nonlinear relationship between photothermal heating and vapor pressure. Credit: Pratiksha Dongare/Rice University

Rice University’s solar-powered approach for purifying salt water with sunlight and nanoparticles is even more efficient than its creators first believed.

Researchers in Rice’s Laboratory for Nanophotonics (LANP) this week showed they could boost the efficiency of their solar-powered desalination system by more than 50% simply by adding inexpensive plastic lenses to concentrate sunlight into “hot spots.” The results are available online in the Proceedings of the National Academy of Sciences.

“The typical way to boost performance in solar-driven systems is to add solar concentrators and bring in more light,” said Pratiksha Dongare, a graduate student in applied physics at Rice’s Brown School of Engineering and co-lead author of the paper. “The big difference here is that we’re using the same amount of light. We’ve shown it’s possible to inexpensively redistribute that power and dramatically increase the rate of purified water production.”

In conventional membrane distillation, hot, salty water is flowed across one side of a sheetlike membrane while cool, filtered water flows across the other. The temperature difference creates a difference in vapor pressure that drives water vapor from the heated side through the membrane toward the cooler, lower-pressure side. Scaling up the technology is difficult because the temperature difference across the membrane—and the resulting output of clean water—decreases as the size of the membrane increases. Rice’s “nanophotonics-enabled solar membrane distillation” (NESMD) technology addresses this by using light-absorbing nanoparticles to turn the membrane itself into a solar-driven heating element.

Rice University researchers (from left) Pratiksha Dongare, Alessandro Alabastri and Oara Neumann showed that Rice’s ‘nanophotonics-enabled solar membrane distillation’ (NESMD) system was more efficient when the size of the device was scaled up and light was concentrated in ‘hot spots.’ Credit: Jeff Fitlow/Rice University

Dongare and colleagues, including study co-lead author Alessandro Alabastri, coat the top layer of their membranes with low-cost, commercially available nanoparticles that are designed to convert more than 80% of sunlight energy into heat. The solar-driven nanoparticle heating reduces production costs, and Rice engineers are working to scale up the technology for applications in remote areas that have no access to electricity.

The concept and particles used in NESMD were first demonstrated in 2012 by LANP director Naomi Halas and research scientist Oara Neumann, who are both co-authors on the new study. In this week’s study, Halas, Dongare, Alabastri, Neumann and LANP physicist Peter Nordlander found they could exploit an inherent and previously unrecognized nonlinear relationship between incident light intensity and vapor pressure.

Alabastri, a physicist and Texas Instruments Research Assistant Professor in Rice’s Department of Electrical and Computer Engineering, used a simple mathematical example to describe the difference between a linear and nonlinear relationship. “If you take any two numbers that equal 10—seven and three, five and five, six and four—you will always get 10 if you add them together. But if the process is nonlinear, you might square them or even cube them before adding. So if we have nine and one, that would be nine squared, or 81, plus one squared, which equals 82. That is far better than 10, which is the best you can do with a linear relationship.”

In the case of NESMD, the nonlinear improvement comes from concentrating sunlight into tiny spots, much like a child might with a magnifying glass on a sunny day. Concentrating the light on a tiny spot on the membrane results in a linear increase in heat, but the heating, in turn, produces a nonlinear increase in vapor pressure. And the increased pressure forces more purified steam through the membrane in less time.

Researchers from Rice University’s Laboratory for Nanophotonics found they could boost the efficiency of their solar-powered desalination system by more than 50% by adding inexpensive plastic lenses to concentrate sunlight into “hot spots.” . Credit: Pratiksha Dongare/Rice University

“We showed that it’s always better to have more photons in a smaller area than to have a homogeneous distribution of photons across the entire membrane,” Alabastri said.

Halas, a chemist and engineer who’s spent more than 25 years pioneering the use of light-activated nanomaterials, said, “The efficiencies provided by this nonlinear optical process are important because water scarcity is a daily reality for about half of the world’s people, and efficient solar distillation could change that.

“Beyond water purification, this nonlinear optical effect also could improve technologies that use solar heating to drive chemical processes like photocatalysis,” Halas said.

For example, LANP is developing a copper-based nanoparticle for converting ammonia into hydrogen fuel at ambient pressure.

Halas is the Stanley C. Moore Professor of Electrical and Computer Engineering, director of Rice’s Smalley-Curl Institute and a professor of chemistry, bioengineering, physics and astronomy, and materials science and nanoengineering.

NESMD is in development at the Rice-based Center for Nanotechnology Enabled Water Treatment (NEWT) and won research and development funding from the Department of Energy’s Solar Desalination program in 2018.

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Explore further

Freshwater from salt water using only solar energy: Modular, off-grid desalination technology

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More information: Pratiksha D. Dongare et al, Solar thermal desalination as a nonlinear optical process, Proceedings of the National Academy of Sciences (2019). DOI: 10.1073/pnas.1905311116

Journal information: Proceedings of the National Academy of Sciences

Provided by Rice University