Brigham and Women’s Hospital: Elastic Gel to Help Heal Wounds


BWH 070215 id40662A team of bioengineers at Brigham and Women’s Hospital (BWH), led by Ali Khademhosseini, PhD, and Nasim Annabi, PhD, of the Biomedical Engineering Division, has developed a new protein-based gel that, when exposed to light, mimics many of the properties of elastic tissue, such as skin and blood vessels. In a paper published in Advanced Functional Materials (“A Highly Elastic and Rapidly Crosslinkable Elastin-Like Polypeptide-Based Hydrogel for Biomedical Applications”), the research team reports on the new material’s key properties, many of which can be finely tuned, and on the results of using the material in preclinical models of wound healing.
ELP Hydrogel
Bioengineers have developed a new protein-based gel that, when exposed to light, mimics many of the properties of elastic tissue, such as skin and blood vessels. (Courtesy of Nasim Annabi, Brigham and Women’s Hospital)
“We are very interested in engineering strong, elastic materials from proteins because so many of the tissues within the human body are elastic. If we want to use biomaterials to regenerate those tissues, we need elasticity and flexibility,” said Annabi, a co-senior author of the study. “Our hydrogel is very flexible, made from a biocompatible polypeptide and can be activated using light.”
“Hydrogels – jelly-like materials that can mimic the properties of human tissue – are widely used in biomedicine, but currently available materials have limitations. Some synthetic gels degrade into toxic chemicals over time, and some natural gels are not strong enough to withstand the flow of arterial blood through them,” said Khademhosseini.
The new material, known as a photocrosslinkable elastin-like polypeptide-based (ELP) hydrogel, offers several benefits. This elastic hydrogel is formed by using a light-activated polypeptide. When exposed to light, strong bonds form between the molecules of the gel, providing mechanical stability without the need for any chemical modifiers to be added to the material.
The team reports that ELP hydrogel can be digested overtime by naturally-occurring enzymes and does not appear to have toxic effects when tested with living cells in the lab. The team also found that they could control how much the material swelled as well its strength, finding that the ELP hydrogel could withstand more stretching than experienced by arterial tissue in the body.
“Our hydrogel has many applications: it could be used as a scaffold to grow cells or it can be incorporated with cells in a dish and then injected to stimulate tissue growth,” said Annabi. “In addition, the material can be used as a sealant, sticking to the tissue at the site of injury and creating a barrier over a wound.”
The researchers found that it was possible to combine the gel with silica nanoparticles – microscopic particles previously found to stop bleeding – to develop an even more powerful barrier to promote wound healing.
“This could allow us to immediately stop bleeding with one treatment,” said Annabi. “We see great potential for use in the clinic. Our method is simple, the material is biocompatible, and we hope to see it solve clinical problems in the future.”
Further investigation in pre-clinical models will be needed to test the material’s properties and safety before approval for use in humans.
Source: Brigham and Women’s Hospital

MIT: Chemists Design a Quantum-Dot Spectrometer: Applications: Smartphones, Diagnostics, Sensors


QD Spectrometer Cell Phones 070215 id40654Instruments that measure the properties of light, known as spectrometers, are widely used in physical, chemical, and biological research. These devices are usually too large to be portable, but MIT scientists have now shown they can create spectrometers small enough to fit inside a smartphone camera, using tiny semiconductor nanoparticles called quantum dots.
Such devices could be used to diagnose diseases, especially skin conditions, or to detect environmental pollutants and food conditions, says Jie Bao, a former MIT postdoc and the lead author of a paper describing the quantum dot spectrometers in the July 2 issue of Nature (“A colloidal quantum dot spectrometer”).
In this illustration, the Quantum Dot (QD) spectrometer device is printing QD filters
In this illustration, the Quantum Dot (QD) spectrometer device is printing QD filters — a key fabrication step. Other spectrometer approaches have complicated systems in order to create the optical structures needed. Here in the QD spectrometer approach, the optical structure — QD filters — are generated by printing liquid droplets. This approach is unique and advantageous in terms of flexibility, simplicity, and cost reduction. (Image: Mary O’Reilly)
This work also represents a new application for quantum dots, which have been used primarily for labeling cells and biological molecules, as well as in computer and television screens.
“Using quantum dots for spectrometers is such a straightforward application compared to everything else that we’ve tried to do, and I think that’s very appealing,” says Moungi Bawendi, the Lester Wolfe Professor of Chemistry at MIT and the paper’s senior author.
Shrinking spectrometers
The earliest spectrometers consisted of prisms that separate light into its constituent wavelengths, while current models use optical equipment such as diffraction gratings to achieve the same effect. Spectrometers are used in a wide variety of applications, such as studying atomic processes and energy levels in physics, or analyzing tissue samples for biomedical research and diagnostics.
Replacing that bulky optical equipment with quantum dots allowed the MIT team to shrink spectrometers to about the size of a U.S. quarter, and to take advantage of some of the inherent useful properties of quantum dots.
Quantum dots, a type of nanocrystals discovered in the early 1980s, are made by combining metals such as lead or cadmium with other elements including sulfur, selenium, or arsenic. By controlling the ratio of these starting materials, the temperature, and the reaction time, scientists can generate a nearly unlimited number of dots with differences in an electronic property known as bandgap, which determines the wavelengths of light that each dot will absorb.
However, most of the existing applications for quantum dots don’t take advantage of this huge range of light absorbance. Instead, most applications, such as labeling cells or new types of TV screens, exploit quantum dots’ fluorescence — a property that is much more difficult to control, Bawendi says. “It’s very hard to make something that fluoresces very brightly,” he says. “You’ve got to protect the dots, you’ve got to do all this engineering.”
Scientists are also working on solar cells based on quantum dots, which rely on the dots’ ability to convert light into electrons. However, this phenomenon is not well understood, and is difficult to manipulate.
On the other hand, quantum dots’ absorption properties are well known and very stable. “If we can rely on these properties, it is possible to create applications that will have a greater impact in the relative short term,” Bao says.
Broad spectrum
The new quantum dot spectrometer deploys hundreds of quantum dot materials that each filter a specific set of wavelengths of light. The quantum dot filters are printed into a thin film and placed on top of a photodetector such as the charge-coupled devices (CCDs) found in cellphone cameras.
The researchers created an algorithm that analyzes the percentage of photons absorbed by each filter, then recombines the information from each one to calculate the intensity and wavelength of the original rays of light.
The more quantum dot materials there are, the more wavelengths can be covered and the higher resolution can be obtained. In this case, the researchers used about 200 types of quantum dots spread over a range of about 300 nanometers. With more dots, such spectrometers could be designed to cover an even wider range of light frequencies.
“Bawendi and Bao showed a beautiful way to exploit the controlled optical absorption of semiconductor quantum dots for miniature spectrometers. They demonstrate a spectrometer that is not only small, but also with high throughput and high spectral resolution, which has never been achieved before,” says Feng Wang, an associate professor of physics at the University of California at Berkeley who was not involved in the research.
If incorporated into small handheld devices, this type of spectrometer could be used to diagnose skin conditions or analyze urine samples, Bao says. They could also be used to track vital signs such as pulse and oxygen level, or to measure exposure to different frequencies of ultraviolet light, which vary greatly in their ability to damage skin.
“The central component of such spectrometers — the quantum dot filter array — is fabricated with solution-based processing and printing, thus enabling significant potential cost reduction,” Bao adds.
Source: By Anne Trafton, MIT

Self-assembled 2D materials for cheaper solar energy storage


  
Posted: Jul 01, 2015

Storing solar energy as hydrogen is a promising way for developing comprehensive renewable energy systems. To accomplish this, traditional solar panels can be used to generate an electrical current that splits water molecules into oxygen and hydrogen, the latter being considered a form of solar fuel. 

However, the cost of producing efficient solar panels makes water-splitting technologies too expensive to commercialize. EPFL scientists have now developed a simple, unconventional method to fabricate high-quality, efficient solar panels for direct solar hydrogen production with low cost. The work is published in Nature Communications (” Self-assembled 2D WSe2 thin films for photoelectrochemical hydrogen production”).

Tungsten Diselinide Thin Film
Many different materials have been considered for use in direct solar-to-hydrogen conversion technologies but “2-D materials” have recently been identified as promising candidates. In general these materials–which famously include graphene–have extraordinary electronic properties. However, harvesting usable amounts of solar energy requires large areas of solar panels, and it is notoriously difficult and expensive to fabricate thin films of 2-D materials at such a scale and maintain good performance.

Kevin Sivula and colleagues at EPFL addressed this problem with an innovative and cheap method that uses the boundary between two non-mixing liquids. The researchers focused on one of the best 2-D materials for solar water splitting, called “tungsten diselenide”. Past studies have shown that this material has a great efficiency for converting solar energy directly into hydrogen fuel while also being highly stable.

Before making a thin film of it, the scientists first had to achieve an even dispersion of the material. To do this, they mixed the tungsten diselenide powder with a liquid solvent using sonic vibrations to “exfoliate” it into thin, 2-D flakes, and then added special chemicals to stabilize the mix. Developed by Sivula’s lab (2014), this technique produces an even dispersion of the flakes that is similar to an ink or a paint.

The researchers then used an out-of-the-box innovation to produce high-quality thin films: they injected the tungsten diselenide ink at the boundary between two liquids that do not mix. Exploiting this oil-and-water effect, they used the interface of the two liquids as a “rolling pin” that forced the 2-D flakes to form an even and high-quality thin film with minimal clumping and restacking. The liquids were then carefully removed and the thin film was transferred to a flexible plastic support, which is much less expensive than a traditional solar panel.

The thin film produced like this was tested and found to be superior in efficiency to films made with the same material but using other comparable methods. At this proof-of-concept stage, the solar-to-hydrogen conversion efficiency was around 1%–already a vast improvement over thin films prepared by other methods, and with considerable potential for higher efficiencies in the future.

More importantly, this liquid-liquid method can be scaled up on a commercial level. “It is suitable for rapid and large-area roll-to-roll processing,” says Kevin Sivula. “Considering the stability of these materials and the comparative ease of our deposition method, this represents an important advance towards economical solar-to-fuel energy conversion.”

Source: Ecole Polytechnique Fédérale de Lausanne

Researchers develop new storage cell for solar energy storage, nighttime conversion


UT Solar En Storage 070115 id40649A University of Texas at Arlington materials science and engineering team has developed a new energy cell that can store large-scale solar energy even when it’s dark.
The innovation is an advancement over the most common solar energy systems that rely on using sunlight immediately as a power source. Those systems are hindered by not being able to use that solar energy at night or when cloudy conditions exist.
The UT Arlington team developed an all-vanadium photo-electrochemical flow cell that allows for efficient and large-scale solar energy storage even at nighttime. The team is now working on a larger prototype.
“This research has a chance to rewrite how we store and use solar power,” said Fuqiang Liu, an assistant professor in the Materials Science and Engineering Department who led the research team. “As renewable energy becomes more prevalent, the ability to store solar energy and use it as a renewable alternative provides a sustainable solution to the problem of energy shortage. It also can effectively harness the inexhaustible energy from the sun.”
Dong Liu (left), Zi Wei (center) and Fuqiang Liu
Dong Liu (left), Zi Wei (center) and Fuqiang Liu, an assistant professor in the UT Arlington Materials Science and Engineering Department.
The work is a product of the 2013 National Science Foundation $400,000 Faculty Early Career Development grant awarded to Liu to improve the way solar energy is captured, stored and transmitted for use. Other members of the team included lead author Dong Liu, who recently defended his UT Arlington Ph.D. dissertation in 2015, and Zi Wei, a UT Arlington doctoral candidate.
The research is detailed in “Reversible Electron Storage in an All-Vanadium Photoelectrochemical Storage Cell: Synergy between Vanadium Redox and Hybrid Photocatalyst”, in the most recent edition of the American Chemical Society journal ACS Catalysis.
Khosrow Behbehani, dean of the College of Engineering, said the groundbreaking research has the potential to positively impact on the way we generate and consume energy.
“Dr. Liu and his colleagues are working to help us shape a more sustainable future and are taking innovative steps to improve our ability to harness and use one of the larger sources of energy available to us – the sun,” Behbehani said.
Dong Liu, lead author of the paper, said a major drawback of current solar technology is the limitation on storing energy under dark conditions.
“We have demonstrated simultaneously reversible storage of both solar energy and electrons in the cell,” Dong Liu said. “Release of the stored electrons under dark conditions continues solar energy storage, thus allowing for unintermittent storage around the clock.”
Wei, another co-author of the paper, said that the research should allow solar energy storage to be done in a much higher capacity and on a much larger scale.
“Using an all-vanadium photo-electrochemical cell gives our energy storage an edge over other systems,” Wei said. “This cell allows us to attain higher storage capacity in a smaller unit. “
Source: University of Texas at Arlington

UC Berkley: Lawrence Berkley National Laboratory: Magnesium Nanoparticles Improve Hydrogen Storage


Hydorgen Storage 063015 id40624The dream of a cleaner, greener transportation future burns brightly in the promise of hydrogen-fueled, internal combustion engine automobiles. Modern-day versions of such vehicles run hot, finish clean and produce only pure water as a combustion byproduct.
But whether those vehicles ever cross over from the niche marketplace to become the mainstay of every garage may depend on how well we can address lingering technical and infrastructure hurdles that stand in the way of their widespread use. One of these is the fuel tank — how do you engineer them so that they can be more like gasoline tanks, which are relatively safe, easy to fill, carry you hundreds of miles and can be refueled again and again with no loss of performance?
This week in the journal Applied Physics Letters, from AIP Publishing (“Size-dependent mechanical properties of Mg nanoparticles used for hydrogen storage”), a team of researchers in the United States and China has taken a step toward that solution. They describe the physics of magnesium hydride, one type of material that potentially could be used to store hydrogen fuel in future automobiles and other applications. Using a technique known as in situ transmission electron microscopy, the team tested different sized nanoparticles of magnesium hydride to gauge their mechanical properties and discovered lessons on how one might engineer the nanoparticles to make them better.
Smaller Mg nanoparticles display better mechanical performance
Smaller Mg nanoparticles display better mechanical performance that is good for structural stability during cycling and also hydrogen storage kinetics. (Image: Qian Yu/Zhejiang University)
“Smaller particles have better mechanical properties, including better plastic stability,” said Qian Yu, the lead author on the paper. “Our work explained why.”
Yu is affiliated with Zhejiang University in Hangzhou, China; the University of California, Berkeley and Lawrence Berkeley National Laboratory.
Other collaborators on the work are affiliated with the University of Michigan in Ann Arbor; General Motors Research and Development Center in Warren, Michigan; and Shanghai Jiaotong University in Shanghai, China.
The Problem of Storing Hydrogen with Magnesium
Hydrogen storage for automobile engines is still something of an application in search of its technology. We know that the next generation of hydrogen fuel tanks will need to offer greater storage capacities and better gas exchange kinetics than existing models, but we don’t know exactly what it will take to deliver that.
One possibility is to use a material like magnesium hydride, long seen as a promising medium for storage. Magnesium readily binds hydrogen, and so the idea is that you could take a tank filled with magnesium, pump in hydrogen and then pump it out as needed to run the engine.
But this approach is hampered by slow kinetics of adsorption and desorption — the speed with which molecular hydrogen binds to and is released from the magnesium. This is ultimately tied to the how the material binds to hydrogen at the molecular level, and so in recent years researchers have sought to better engineer magnesium to achieve better kinetics.
Previous work had already shown that smaller magnesium nanoparticles have better hydrogen storage properties, but nobody understood why. Some thought it was primarily the greater overall magnesium surface area within the tank realized by milling smaller particles. But Yu and colleagues showed that it is also highly related to how the particles respond to deformation during cycles of fueling and emptying the tank.
Fuel cycles in a hydrogen tank introduce tremendous internal changes in pressure, which can deform the particles, cracking or degrading them. Smaller particles have greater plastic stability, meaning that they are more able to retain their structure even when undergoing deformation. This means that the smaller, more plastic magnesium nanoparticles can retain their structure longer and continue to hold hydrogen cycle after cycle.
But it turns out that in addition to greater plastic stability, the smaller particles also have less “deformation anisotropy” — a measure of how the magnesium nanoparticles all tend to respond, uniformly or not, across the entire tank. Deformation anisotropy is strongly reduced at nanoscales, Yu said, and because of this, smaller magnesium nanoparticles have more homogeneous dislocation activity inside, which offer more homogenously distributed diffusion path for hydrogen.
This suggests a path forward for making better hydrogen storage tanks, Yu said, by engineering them specifically to take advantage of greater homogeneous dislocation. Next they plan to do similar studies on hydrogen storage materials as they undergo fuel cycling, absorbing and desorbing hydrogen in the process.
Source: American Institute of Physics

Chitosan Coated, Chemotherapy Packed Nanoparticles may Target Cancer Stem Cells


Phenformin Nano Cancer Delivery id39449Chitosan coated, chemotherapy packed nanoparticles may target cancer stem cells

COLUMBUS, Ohio – Nanoparticles packed with a clinically used chemotherapy drug and coated with an oligosaccharide derived from the carapace of crustaceans might effectively target and kill cancer stem-like cells, according to a recent study led by researchers at The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute (OSUCCC – James). Cancer stem-like cells have characteristics of stem cells and are present in very low numbers in tumors. They are highly resistant to chemotherapy and radiation and are believed to play an important role in tumor recurrence. This laboratory and animal study showed that nanoparticles coated with the oligosaccharide called chitosan and encapsulating the chemotherapy drug doxorubicin can target and kill cancer stem-like cells six times more effectively than free doxorubicin.

The study is reported in the journal ACS Nano.

“Our findings indicate that this nanoparticle delivery system increases the cytotoxicity of doxorubicin with no evidence of systemic toxic side effects in our animal model,” says principal investigator Xiaoming (Shawn) He, PhD, associate professor of Biomedical Engineering and a member of the OSUCCC – James Translational Therapeutics Program.

“We believe that chitosan-decorated nanoparticles could also encapsulate other types of chemotherapy and be used to treat many types of cancer.”

This study showed that chitosan binds with a receptor on cancer stem-like cells called CD44, enabling the nanoparticles to target the malignant stem-like cells in a tumor.

The nanoparticles were engineered to shrink, break open, and release the anticancer drug under the acidic conditions of the tumor microenvironment and in tumor-cell endosomes and lysosomes, which cells use to digest nutrients acquired from their microenvironment.vnDpjc0OLw.JPG

He and his colleagues conducted the study using models called 3D mammary tumor spheroids (i.e., mammospheres) and an animal model of human breast cancer.

The study also found that although the drug-carrying nanoparticles could bind to the variant CD44 receptors on cancerous mammosphere cells, they did not bind well to the CD44 receptors that were overexpressed on noncancerous stem cells.

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Funding from an American Cancer Society Research Scholar Grant (No. 120936-RSG- 11-109-01-CDD) and a Pelotonia postdoctoral fellowship supported this research.

Other researchers involved in this study were Wei Rao, Hai Wang, Jianfeng Han, Shuting Zhao, Jenna Dumbleton, Pranay Agarwal, Jianhua Yu and Debra L. Zynger of Ohio State; Wujie Zhang of Milwaukee School of Engineering; Gang Zhao of University of Science and Technology of China; and Xiongbin Lu of The University of Texas MD Anderson Cancer Center.

The Ohio State University Comprehensive Cancer Center – Arthur G. James Cancer Hospital and Richard J. Solove Research Institute strives to create a cancer-free world by integrating scientific research with excellence in education and patient-centered care, a strategy that leads to better methods of prevention, detection and treatment. Ohio State is one of only 41 National Cancer Institute (NCI)-designated Comprehensive Cancer Centers and one of only four centers funded by the NCI to conduct both phase I and phase II clinical trials. The NCI recently rated Ohio State’s cancer program as “exceptional,” the highest rating given by NCI survey teams. As the cancer program’s 306-bed adult patient-care component, The James is a “Top Hospital” as named by the Leapfrog Group and one of the top cancer hospitals in the nation as ranked by U.S.News & World Report.

18 Charts Show What the Next Generation of Development Professionals Will Look Like


Devex infographic_d4By Kate Warren, Devex
Infographics by Sophie Greenbaum, PSI

What will the 21st century development professional look like? What skills will they need? How will they measure success? How will funding change in the next 10 years?

These questions, and more, were asked of more than 1,000 development professionals in a survey conducted by Devex, in partnership with PSI and the US Global Development Lab at USAID.  And the results were illuminating.

For example, sustainability was rated as the most important approach in which to be proficient according to development professionals. Capacity-building, community-based approaches, data-driven and evidence-based programming and innovation followed.

When you download the full report, you’ll discover:

  • What types of development workers will be valued in the future: integrators, specialists, generalists or disrupters.
  • How development professionals believe aid will be invested in the future.
  • Whether aid workers believe they can keep working with a single funder or will need to work with a diverse range.
  • What industry sectors future aid workers will come from.
  • How the tools of the trade will change.
  • What skills from the technology sector are most likely to be integrated in development work (i.e., human-centered design, market-based approaches, crowd-sourcing solutions, gamification).
  • What soft skills are needed (i.e., empathy, resourcefulness, adaptability, implementation skills, or collaboration).
  • How older development professionals view critical skills differently than younger professionals.
  • What skills gaps current development professionals feel they have.
  • What skills health professionals are most interested in developing.
  • What level of education future development professionals will need.
  • What language skills (and which languages) are believed to be most important in 10 years.

*** Some Example Infographics from the Report ***

Check out all of the survey results below. (You can also click on the link/ infographic to see or download the full survey.)

https://www.dropbox.com/s/9mfp9skko2rsdeo/Devex-infographic_FINAL.pdf?dl=0

And more! So download your PDF copy today. And feel free to share it with your colleagues, co-workers and friends!