Quantum Dots may turn House Windows into Solar Panels

 

A house window that doubles as a solar panel could be on the horizon, thanks to recent quantum-dot work by researchers at Los Alamos National Laboratory in the US in collaboration with scientists from University of Milano-Bicocca (UNIMIB) in Italy.

Their work, published earlier this year in Nature Photonics, demonstrates that superior light-emitting properties of quantum dots can be applied in solar energy by helping more efficiently harvest sunlight.

“The key accomplishment is the demonstration of large-area luminescent solar concentrators that use a new generation of specially engineered quantum dots,” said lead researcher Victor Klimov of the Center for Advanced Solar Photophysics at Los Alamos. Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry.

A luminescent solar concentrator (LSC) is a photon-management device, representing a slab of transparent material that contains highly efficient emitters such as dye molecules or quantum dots. Sunlight absorbed in the slab is re-radiated at longer wavelengths and guided toward the slab edge equipped with a solar cell.

Quantum dots are embedded in the plastic matrix and capture sunlight to improve solar-panel efficiency.
Courtesy Los Alamos Lab.

 

LUMINESCENT SOLAR CONCENTRATOR AS LIGHT HARVESTER

Sergio Brovelli, a faculty member at UNIMIB and a co-author of the paper, explained, “The LSC serves as a light-harvesting antenna which concentrates solar radiation collected from a large area onto a much smaller solar cell, and this increases its power output. LSCs are especially attractive because in addition to gains in efficiency, they can enable new interesting concepts such as photovoltaic windows that can transform house facades into large-area energy-generation units.”

Because of highly efficient, color-tunable emission and solution processability, quantum dots are attractive materials for use in inexpensive, large-area LSCs. To overcome a nagging problem of light reabsorption, the Los Alamos and UNIMIB researchers developed LSCs based on quantum dots with artificially induced large separation between emission and absorption bands, known as a large Stokes shift.

These “Stokes-shift-engineered” quantum dots represent cadmium selenide/cadmium sulfide (CdSe/CdS) structures in which light absorption is dominated by an ultra-thick outer shell of CdS, while emission occurs from the inner core of a narrower-gap CdSe.

Los Alamos researchers created a series of thick-shell (so-called “giant”) CdSe/CdS quantum dots, which were incorporated by their Italian partners into large slabs (sized in tens of centimeters across) of polymethylmethacrylate. While being large by quantum dot standards, the active particles are still tiny, only about hundred angstroms across.

QUANTUM DOTS USED FOR NEW DISPLAYS

Quantum dots are ultra-small bits of semiconductor matter that can be synthesized with nearly atomic precision via modern methods of colloidal chemistry.

Their emission color can be tuned by simply varying their dimensions. Color tunability is combined with high emission efficiencies approaching 100%.

These properties have recently become the basis of a new technology — quantum-dot displays — employed, for example, in the newest generation of the Kindle Fire e-reader.

In a new SPIE.TV video, Lawrence Berkeley National Lab director Paul Alivisatos demonstrates the Kindle Fire quantum-dot display.

 

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DOI: 10.1117/2.4201407.10

Subcommittee Examines Breakthrough Nanotechnology Opportunities for America

SUBCOMMITTE EXAMINES BREAKTHROUGH NANOTECHNOLOGY OPPORTUNITIES FOR AMERICA

July 29, 2014

 

Chairman Terry: “Nanotech is a true science race between the nations, and we should be encouraging the transition from research breakthroughs to commercial development.”

WASHINGTON, DC – The Subcommittee on Commerce, Manufacturing, and Trade, chaired by Rep. Lee Terry (R-NE), today held a hearing on “Nanotechnology: Understanding How Small Solutions Drive Big Innovation.” Nanotechnology is science, engineering, and technology conducted at the nanoscale, which is approximately 1 to 100 nanometers (one nanometer is a billionth of a meter). This technology brings great opportunities to advance a broad range of industries, bolster our U.S. economy, and create new manufacturing jobs. Members heard from several nanotech industry leaders about the current state of nanotechnology and the direction that it is headed.

“Just as electricity, telecommunications, and the combustion engine fundamentally altered American economics in the ‘second industrial revolution,’ nanotechnology is poised to drive the next surge of economic growth across all sectors,” said Chairman Terry.

 

 

Dr. Christian Binek, Associate Professor at the University of Nebraska-Lincoln, explained the potential of nanotechnology to transform a range of industries, stating, “Virtually all of the national and global challenges can at least in part be addressed by advances in nanotechnology. Although the boundary between science and fiction is blurry, it appears reasonable to predict that the transformative power of nanotechnology can rival the industrial revolution. Nanotechnology is expected to make major contributions in fields such as; information technology, medical applications, energy, water supply with strong correlation to the energy problem, smart materials, and manufacturing. It is perhaps one of the major transformative powers of nanotechnology that many of these traditionally separated fields will merge.”

Dr. James M. Tour at the Smalley Institute for Nanoscale Science and Technology at Rice University encouraged steps to help the U.S better compete with markets abroad. “The situation has become untenable. Not only are our best and brightest international students returning to their home countries upon graduation, taking our advanced technology expertise with them, but our top professors also are moving abroad in order to keep their programs funded,” said Tour. “This is an issue for Congress to explore further, working with industry, tax experts, and universities to design an effective incentive structure that will increase industry support for research and development – especially as it relates to nanotechnology. This is a win-win for all parties.”

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Professor Milan Mrksich of Northwestern University discussed the economic opportunities of nanotechnology, and obstacles to realizing these benefits. He explained, “Nanotechnology is a broad-based field that, unlike traditional disciplines, engages the entire scientific and engineering enterprise and that promises new technologies across these fields. … Current challenges to realizing the broader economic promise of the nanotechnology industry include the development of strategies to ensure the continued investment in fundamental research, to increase the fraction of these discoveries that are translated to technology companies, to have effective regulations on nanomaterials, to efficiently process and protect intellectual property to ensure that within the global landscape, the United States remains the leader in realizing the economic benefits of the nanotechnology industry.”

James Phillips, Chairman & CEO at NanoMech, Inc., added, “It’s time for America to lead. … We must capitalize immediately on our great University system, our National Labs, and tremendous agencies like the National Science Foundation, to be sure this unique and best in class innovation ecosystem, is organized in a way that promotes nanotechnology, tech transfer and commercialization in dramatic and laser focused ways so that we capture the best ideas into patents quickly, that are easily transferred into our capitalistic economy so that our nation’s best ideas and inventions are never left stranded, but instead accelerated to market at the speed of innovation so that we build good jobs and improve the quality of life and security for our citizens faster and better than any other country on our planet.”

Chairman Terry concluded, “Nanotech is a true science race between the nations, and we should be encouraging the transition from research breakthroughs to commercial development. I believe the U.S. should excel in this area.”

– See more at: http://energycommerce.house.gov/press-release/subcommittee-examines-breakthrough-nanotechnology-opportunities-america#sthash.YnSzFU10.dpuf

‘Bricks-and-Mortar’ Assembly of New Molecular Structures Demonstrated by Chemists at Indiana University

 

Chemists at Indiana University Bloomington have described the self-assembly of large, symmetrical molecules in bricks-and-mortar fashion, a development with potential value for the field of organic electronic devices such as field-effect transistors and photovoltaic cells.

 

Their paper, “Anion-Induced Dimerization of 5-fold Symmetric Cyanostars in 3D Crystalline Solids and 2D Self-Assembled Crystals,” has been published online by Chemical Communications, a journal of the Royal Society of Chemistry. It is the first collaboration by Amar Flood, the James F. Jackson Associate Professor of Chemistry, and Steven L. Tait, assistant professor of chemistry. Both are in the materials chemistry program in the IU Bloomington Department of Chemistry, part of the College of Arts and Sciences.

The article will appear as the cover article of an upcoming issue of the journal. The cover illustration was created by Albert William, a lecturer in the media arts and science program of the School of Informatics and Computing at Indiana University-Purdue University Indianapolis. William specializes in using advanced graphics and animation to convey complex scientific concepts.

This artwork will appear on the cover of Chemical Communications. It depicts the cyanostar molecules moving in solution, ordering on the surface, and stacking by anion binding. Imaging of the surface structure is performed by scanning. 

Lead author of the paper is Brandon Hirsch, who earned the cover by winning a poster contest at the fall 2013 meeting of the International Symposium on Macrocyclic and Supramolecular Chemistry. Co-authors, along with Flood and Tait, include doctoral students Semin Lee, Bo Qiao and Kevin P. McDonald and research scientist Chun-Hsing Chen.

The researchers demonstrate the self-assembly and packing of a five-sided, symmetrical molecule, called cyanostar, that was developed by Flood’s IU research team. While researchers have created many such large, cyclic molecules, or macrocycles, cyanostar is unusual in that it can be readily synthesized in a “one pot” process. It also has an unprecedented ability to bind with large, negatively charged anions such as perchlorate.

“This great piece of work, with state-of-the-art studies of the assembly of some beautiful compounds pioneered by the group in Indiana, shows how anions can help organize molecules that could have very interesting properties,” said David Amabilino, nanomaterials group leader at the Institute of Materials Science of Barcelona. “Symmetry is all important when molecules pack together, and here the supramolecular aspects of these compounds with a very particular shape present tantalizing possibilities. This research is conceptually extremely novel and really interdisciplinary: It has really unveiled how anions could help pull molecules together to behave in completely new ways.”

The paper describes how cyanostar molecules bind with anions in 2-to-1 sandwich-like complexes, with anions sandwiched between two saucer-shaped cyanostars. The study shows the packing of the molecules in repeating patterns reminiscent of the two-dimensional packing of pentagons shown by artist Albrecht Durer in 1525. It further shows the packing to take place not only at but away from the surface of materials.

The future of organic electronics will rely upon packing molecules onto electrode surfaces, yet it has been challenging to get packing of the molecules away from the surface, Tait and Flood said. With this paper, they present a collaborative effort, combining their backgrounds in traditionally distinct fields of chemistry, as a new foray to achieve this goal using a bricks-and-mortar approach.

The paper relies on two complementary technologies that provide high-resolution images of molecules:

• X-ray crystallography, which is being celebrated worldwide for its invention 100 years ago, can provide images of molecules from analysis of the three-dimensional crystalline solids.
• Scanning tunneling microscopy, or STM, developed in 1981, shows two-dimensional packing of molecules immobilized on a surface.

The results are distinct, with submolecular views of the star-shaped molecules that are a few nanometers in diameter. (A human hair is about 100,000 nanometers thick).

Explore further: Two teams pave way for advances in 2D materials

 

 

Dye-sensitized solar cell absorbs a broad range of visible and infrared wavelengths: Increases Efficiencies

 

Dye-sensitized solar cells (DSSCs) rely on dyes that absorb light to mobilize a current of electrons and are a promising source of clean energy. Jishan Wu at the A*STAR Institute of Materials Research and Engineering and colleagues in Singapore have now developed zinc porphyrin dyes that harvest light in both the visible and near-infrared parts of the spectrum1. Their research suggests that chemical modification of these dyes could enhance the energy output of DSSCs.

DSSCs are easier and cheaper to manufacture than conventional silicon solar cells, but they currently have a lower efficiency. Ruthenium-based dyes have been traditionally used in DSSCs, but in 2011 researchers developed a more efficient dye based on a zinc atom surrounded by a ring-shaped molecule called a porphyrin. Solar cells using this new dye, called YD2-o-C8, convert visible light into electricity with an efficiency of up to 12.3 per cent. Wu’s team aimed to improve that efficiency by developing a zinc porphyrin dye that can also absorb infrared light.

The most successful dyes developed by Wu’s team, WW-5 and WW-6, unite a zinc porphyrin core with a system of fused carbon rings bridged by a nitrogen atom, known as an N-annulated perylene group. Solar cells containing these dyes absorbed more infrared light than YD2-o-C8 and had efficiencies of up to 10.5 per cent, matching the performance of an YD2-o-C8 cell under the same testing conditions (see image).

Zinc porphyrin dyes were used to create solar cells that can absorb both visible and near-infrared light. Credit: A*STAR Institute of Materials Research and Engineering 

Theoretical calculations indicate that connecting the porphyrin and perylene sections of these dyes by a carbon–carbon triple bond, which acts as an electron-rich linker, improved the flow of electrons between them. This bond also reduced the light energy needed to excite electrons in the molecule, boosting the dye’s ability to harvest infrared light.

Adding bulky chemical groups to the dyes also improved their solubility and prevented them from aggregating—something that tends to reduce the efficiency of DSSCs.

However, both WW-5 and WW-6 are slightly less efficient than YD2-o-C8 at converting visible light into electricity, and they also produce a lower voltage. “We are now trying to solve this problem through modifications based on the chemical structure of WW-5 and WW-6,” says Wu.

Comparing the results from more perylene–porphyrin dyes should indicate ways to overcome these hurdles, and may even extend light absorption further into the infrared. “The top priority is to improve the power conversion efficiency,” says Wu. “Our target is to push the efficiency to more than 13 per cent in the near future.”

Explore further: A new way to make microstructured surfaces

More information: Luo, J., Xu, M., Li, R., Huang, K.-W., Jiang, C. et al. N-annulated perylene as an efficient electron donor for porphyrin-based dyes: Enhanced light-harvesting ability and high-efficiency Co(II/III)-based dye-sensitized solar cells. Journal of the American Chemical Society 136, 265–272 (2014). DOI: 10.1021/ja409291g

Rice Nanophotonics Researchers Create ‘Mega- Molecular’ Sensor

Nanophotonics experts at Rice University have created a unique sensor that amplifies the optical signature of molecules by about 100 billion times. Newly published tests found the device could accurately identify the composition and structure of individual molecules containing fewer than 20 atoms.

 

The new imaging method, which is described this week in the journal Nature Communications, uses a form of Raman spectroscopy in combination with an intricate but mass reproducible optical amplifier. Researchers at Rice’s Laboratory for Nanophotonics (LANP) said the single-molecule sensor is about 10 times more powerful that previously reported devices.

“Ours and other research groups have been designing single-molecule sensors for several years, but this new approach offers advantages over any previously reported method,” said LANP Director Naomi Halas, the lead scientist on the study. “The ideal single-molecule sensor would be able to identify an unknown molecule—even a very small one—without any prior information about that molecule’s structure or composition. That’s not possible with current technology, but this new technique has that potential.”

The optical sensor uses Raman spectroscopy, a technique pioneered in the 1930s that blossomed after the advent of lasers in the 1960s. When light strikes a molecule, most of its photons bounce off or pass directly through, but a tiny fraction—fewer than one in a trillion—are absorbed and re-emitted into another energy level that differs from their initial level. By measuring and analyzing these re-emitted photons through Raman spectroscopy, scientists can decipher the types of atoms in a molecule as well as their structural arrangement.

Scientists have created a number of techniques to boost Raman signals. In the new study, LANP graduate student Yu Zhang used one of these, a two-coherent-laser technique called “coherent anti-Stokes Raman spectroscopy,” or CARS. By using CARS in conjunction with a light amplifier made of four tiny gold nanodiscs, Halas and Zhang were able to measure single molecules in a powerful new way. LANP has dubbed the new technique “surface-enhanced CARS,” or SECARS.

                                                                     Yu Zhang

“The two-coherent-laser setup in SECARS is important because the second laser provides further amplification,” Zhang said. “In a conventional single-laser setup, photons go through two steps of absorption and re-emission, and the optical signatures are usually amplified around 100 million to 10 billion times. By adding a second laser that is coherent with the first one, the SECARS technique employs a more complex multiphoton process.”

 

Zhang said the additional amplification gives SECARS the potential to address most unknown samples. That’s an added advantage over current techniques for single-molecule sensing, which generally require a prior knowledge about a molecule’s resonant frequency before it can be accurately measured.

Another key component of the SECARS process is the device’s optical amplifier, which contains four tiny gold discs in a precise diamond-shaped arrangement. The gap in the center of the four discs is about 15 nanometers wide. Owing to an optical effect called a “Fano resonance,” the optical signatures of molecules caught in that gap are dramatically amplified because of the efficient light harvesting and signal scattering properties of the four-disc structure.

Fano resonance requires a special geometric arrangement of the discs, and one of LANP’s specialties is the design, production and analysis of Fano-resonant plasmonic structures like the four-disc “quadrumer.” In previous LANP research, other geometric disc structures were used to create powerful optical processors.

Zhang said the quadrumer amplifiers are a key to SECARS, in part because they are created with standard e-beam lithographic techniques, which means they can be easily mass-produced.

“A 15-nanometer gap may sound small, but the gap in most competing devices is on the order of 1 nanometer,” Zhang said. “Our design is much more robust because even the smallest defect in a one-nanometer device can have significant effects. Moreover, the larger gap also results in a larger target area, the area where measurements take place. The target area in our device is hundreds of times larger than the target area in a one-nanometer device, and we can measure molecules anywhere in that target area, not just in the exact center.”

Halas, the Stanley C. Moore Professor in Electrical and Computer Engineering and a professor of biomedical engineering, chemistry, physics and astronomy at Rice, said the potential applications for SECARS include chemical and biological sensing as well as metamaterials research. She said scientific labs are likely be the first beneficiaries of the technology.

“Amplification is important for sensing small molecules because the smaller the molecule, the weaker the optical signature,” Halas said. “This amplification method is the most powerful yet demonstrated, and it could prove useful in experiments where existing techniques can’t provide reliable data.”

Explore further: Chemical sensor on a chip

Read more at: http://phys.org/news/2014-07-nanophotonics-experts-powerful-molecular-sensor.html#jCp

 

Nanotech-inspired Sensor “Sniffs Out” Explosives

Security forces worldwide rely on sophisticated equipment, trained personnel, and detection dogs to safeguard airports and other public areas against terrorist attacks. A revolutionary new electronic chip with nano-sized chemical sensors is about to make their job much easier.

 

 

The groundbreaking nanotechnology-inspired sensor, devised by Prof. Fernando Patolsky of Tel Aviv University’s School of Chemistry and Center for Nanoscience and Nanotechnology, and developed by the Herzliya company Tracense, picks up the scent of explosives molecules better than a detection dog’s nose. Research on the sensor was recently published in the journal Nature Communications.

Existing explosives sensors are expensive, bulky and require expert interpretation of the findings. In contrast, the new sensor is mobile, inexpensive, and identifies in real time–and with great accuracy–explosives in the air at concentrations as low as a few molecules per 1,000 trillion.

A Nano-nose to Compete with a Dog’s

“Using a single tiny chip that consists of hundreds of supersensitive sensors, we can detect ultra low traces of extremely volatile explosives in air samples, and clearly fingerprint and differentiate them from other non-hazardous materials,” said Prof. Patolsky, a top researcher in the field of nanotechnology. “In real time, it detects small molecular species in air down to concentrations of parts-per-quadrillion, which is four to five orders of magnitude more sensitive than any existing technological method, and two to three orders of magnitude more sensitive than a dog’s nose.

“This chip can also detect improvised explosives, such as TATP (triacetone triperoxide), used in suicide bombing attacks in Israel and abroad,” Prof. Patolsky added.

The clusters of nano-sized transistors used in the prototype are extremely sensitive to chemicals, which cause changes in the electrical conductance of the sensors upon surface contact. When just a single molecule of an explosive comes into contact with the sensors, it binds with them, triggering a rapid and accurate mathematical analysis of the material.

“Animals are influenced by mood, weather, state of health and working hours, the oversaturation of olfactory system, and much more,” said Prof. Patolsky. “They also cannot tell us what they smell. Automatic sensing systems are superior candidates to dogs, working at least as well or better than nature. This is not an easy task, but was achieved through the development of novel technologies such as our sensor.”

Technology for a Safer World

The trace detector, still in prototype, identifies several different types of explosives several meters from the source in real time. It has been tested on the explosives TNT, RDX, and HMX, used in commercial blasting and military applications, as well as peroxide-based explosives like TATP and HMTD. The latter are commonly used in homemade bombs and are very difficult to detect using existing technology.

“Our breakthrough has the potential to change the way hazardous materials are detected, and of course should provide populations with more security,” said Prof. Patolsky. “The faster, more sensitive detection of tiny amounts of explosives in the air will provide for a better and safer world.”

Tracense has invested over $10 million in research and development of the device since 2007, and expects to go to market next year. Prof.Patolsky and his team of researchers are currently performing multiple and extensive field tests of prototype devices of the sensor.

For more information, click here.

Could Nano-Flurophores (Dyes) Improve Surgical Outcomes? (Making Cancer ‘Glow in the Dark’)

The best way to cure most cases of cancer is to surgically remove the tumor. The Achilles heel of this approach, however, is that the surgeon may fail to extract the entire tumor, leading to a local recurrence.

 

With a new technique, researchers at the University of Pennsylvania have established a new strategy to help surgeons see the entire tumor in the patient, increasing the likelihood of a positive outcome. This approach relies on an injectable dye that accumulates in cancerous tissues much more so than normal tissues. When the surgeon shines an infrared light on the cancer, it glows, allowing the surgeon to remove the entire malignancy.

“Surgeons have had two things that tell where a cancer is during surgery: their eyes and their hands,” said David Holt, first author on the study and professor of surgery in Penn’s School of Veterinary Medicine. “This technique is offering surgeons another tool, to light tumors up during surgery.”

Holt collaborated with a team from Penn’s Perelman School of Medicine led by Sunil Singhal, an assistant professor of surgery. Their paper appears in the journal PLOS ONE.

Between 20 and 50 percent of cancer patients who undergo surgery end up experiencing a local recurrence of their cancer, indicating that the surgeon failed to extract all of the diseased tissue from the site. Identifying the margins of a tumor can be difficult to do during a procedure, and typically surgeons have had to do this by simply looking at the tumor and feeling for differences with their fingers.

Seeking an alternative, Holt, Singhal and colleagues turned to near-infrared, or NIR, imaging. They chose to test the only Food and Drug Administration-approved contrast agent for NIR, a dye called indocyanine green, or ICG, that fluoresces a bright green under NIR light. ICG concentrates in tumor tissue more than normal tissue because the blood vessels of tumors have so-called “leaky” walls from growing quickly.

“Since 1958 when ICG was initially FDA approved, it has been used to examine tissue perfusion and clearance studies,” Singhal said. “However, our group has been experimenting with new strategies to use ICG to solve a classic problem in surgical oncology: preventing local recurrences. Our work uses an old dye in a new way.”

To see if visualizing ICG under NIR could help them define cancerous from non-cancerous tissues, the Penn-led team first tested the approach in mice. They administered ICG to mice with a type of lung cancer and found that they could use NIR to distinguish tumors from normal lung tissue as early as 15 days after the mice acquired cancer. These tumors were visible to the human eye by 24 days.

Next the researchers evaluated the technique in eight client-owned dogs, of various breeds and sizes, that had naturally occurring lung cancer and were brought to Penn Vet’s Ryan Veterinary Hospital for surgery. They received ICG intravenously a day before surgery, then surgeons used NIR during the procedure to try to visualize the tumor and distinguish it from normal tissue.

“It worked,” Holt said, the tumors fluorescing clearly enough to permit the surgeon to rapidly distinguish the cancer during surgery. “And because it worked in a spontaneous large animal model, we were able to get approval to start trying it in people.”

A human clinical trial was the final step. Five patients with cancer in their lungs or chest participated in the pilot study at the Hospital of the University of Pennsylvania. Each received an injection of ICG prior to surgery. During the procedure, surgeons removed the tumors, which were then inspected using NIR imaging and biopsied.

All of the tumors strongly fluoresced under the NIR light, confirming that the technique worked in human cancers.

In four of the patients, the surgeon could easily tell tumor from non-tumor by sight and by feel. In a fifth patient, however, though a CT and PET scan indicated that the tumor was a solitary mass, NIR imaging revealed glowing areas in what were thought to be healthy parts of the lung.

“It turns out he had diffuse microscopic cancer in multiple areas of the lung,” Holt said. “We might have otherwise called this Stage I, local disease, and the cancer would have progressed. But because of the imaging and subsequent biospy, he underwent chemotherapy and survived.”

Some other research teams have begun investigating NIR for other applications in cancer surgery, but this is the first time a group has taken the approach from a mouse model to a large animal model of spontaneous disease and all the way to human clinical trials.

One drawback of the technique is that ICG also absorbs into inflamed tissue. So in some patients that had inflamed tissues around their tumors, it was difficult or impossible to tell apart cancer from from inflamed tissue. The Penn researchers are working to identify an alternative targeted contrast agent that is specific to a tumor cell marker to avoid this problem, Holt said.

In addition to Holt and Singhal, the authors on the paper included Penn Medicine’s Olugbenga Okusanya, Ryan Judy, Ollin Venegas, Jack Jiang, Elizabeth DeJesus, Evgeniy Eruslanov, Jon Quatromoni, Pratik Bhojnagarwala, Charuhas Deshpande and Steven Albelda and Emory University’s Shuming Nie.

The work was supported by the American Surgical Association and the National Institutes of Health.

Intraoperative Near-Infrared Imaging Can Distinguish Cancer from Normal Tissue but Not Inflammation

Source: Univ. of Pennsylvania

“Nano” Propellers Used for Microscopic Medicine

If you thought that the most impressive news in shrinking technology these days was smart watches, think again. Scientists are quietly toiling in their laboratories to create robots that are only nanometers—billionths of a meter—in length, small enough to maneuver inside the human body and possibly inside human cells.

The impact of these miraculous microscopic machines on medicine can only be imagined, but there is no doubt that it will be significant.

One of the first steps in creating these robots is figuring out how to make them move. In a paper published in the June 2014 issue of ACS Nano, an Israeli and German team announced that they had succeeded in creating a tiny screw-shaped propeller that can move in a gel-like fluid, mimicking the environment inside a living organism. The team is comprised of researchers from the Technion-Israel Institute of Technology’s Russell Berrie Nanotechnology Institute, the Max Planck Institute for Intelligent Systems, and the Institute for Physical Chemistry at the University of Stuttgart, Germany.

The filament that makes up the propeller, made of silica and nickel, is only 70 nm in diameter; the entire propeller is 400 nm long. (A nanometer is one billionth of a meter.) “If you compare the diameter of the [nanopropellers] with a human blood cell, then the [propellers] are 100 times smaller,” said Peer Fischer, a member of the research team and head of the Micro, Nano, and Molecular Systems Lab at the Max Planck Institute for Intelligent Systems. They are so small, in fact, that their motion can be affected by the motion of nearby molecules (known as Brownian motion).

The team already knew that tiny propellers moved well through water, but to test if they could move through living organisms, they chose hyaluronan, a material that occurs throughout the human body, including the synovial fluids in joints and the vitreous humor in your eyeball. The hyaluronan gel contains a mesh of long proteins called polymers; the polymers are large enough to prevent micrometer-sized propellers from moving much at all. But the openings are large enough for nanometer-sized objects to pass through. The scientists were able to control the motion of the propellers using a relatively weak rotating magnetic field.

The findings were somewhat surprising. The team expected that they would have trouble controlling the motion of the nanopropellers, since at their size they start to be governed by diffusion, just as if they were molecules. But because the nanopropellers are the same size as the mesh in the gel, they “actually display significantly enhanced propulsion velocities, exceeding the highest speeds measured in glycerin as compared with micro-propellers, which show very low or negligible propulsion,” said study co-author Associate Professor Alex Leshanksy of the Technion Faculty of Chemical Engineering.

While the nanopropellers are astonishing for their technical complexity, the real significance is how they might affect medicine. “One can now think about targeted applications, for instance in the eye where they may be moved to a precise location at the retina,” says Fischer. Scientists could also attach “active molecules” to the tips of the propellers, or use the propellers to deliver tiny doses of radiation. The applications seem wide, varied, and exciting.

Source: American Technion Society

Wyss Institute’s Technology Translation Model Launches “Organs on a Chip” for Commercialization

The Wyss Institute for Biologically Inspired Engineering at Harvard University announced that its human “Organs-on-Chips” technology will be commercialized by a newly formed private company to accelerate development of pharmaceutical, chemical, cosmetic and personalized medicine products. The announcement follows a worldwide license agreement between Harvard’s Office of Technology Development (OTD) and the start-up Emulate Inc., relating to the use of the Institute’s automated human Organs-on-Chips platform.

“This is a big win towards achieving our Institute’s mission of transforming medicine and the environment by developing breakthrough technologies and facilitating their translation from the benchtop to the marketplace,” said Wyss Institute Founding Director Don Ingber, MD, PhD and leader of the Wyss Institute’s Organs-on-Chips effort.

Created with microchip manufacturing methods, an Organ-on-a-Chip is a cell culture device, the size of a computer memory stick, that contains hollow channels lined by living cells and tissues that mimic organ-level physiology. These devices produce levels of tissue and organ functionality not possible with conventional culture systems, while permitting real-time analysis of biochemical, genetic and metabolic activities within individual cells.

The Wyss Institute team also has developed an instrument to automate the Organs-on-Chips, and to link them together by flowing medium that mimics blood to create a “Human-Body-on-Chips” and better replicate whole body-level responses. This automated human Organ-on-Chip platform could represent an important step towards more predictive and useful measures of the efficacy and safety of potential new drugs, chemicals and cosmetics, while reducing the need for traditional animal testing. Human Organs-on-Chips lined by patient-derived stem cells also could potentially provide a way to develop personalized therapies in the future.

The Wyss Institute’s human “Organs-on-Chips” team has used the lung-on-a-chip shown here to study drug toxicity and potential new therapies. The technology will be commercialized to accelerate development of pharmaceutical, chemical, cosmetic and personalized medicine products. Image: Harvard’s Wyss Institute

The technology’s rapid development from demonstration of the first functional prototypes to multiple human Organs-on-Chips that can be integrated on a common instrument platform also speaks to the Institute’s ability to translate academic innovation into commercially valuable technologies in a big and meaningful way.

“We took a game-changing advance in microengineering made in our academic lab, and in just a handful of years, turned it into a technology that is now poised to have a major impact on society. The Wyss Institute is the only place this could happen,” added Ingber, who is also the Judah Folkman Professor of Vascular Biology at Harvard Medical School and Boston Children’s Hospital, and Professor of Bioengineering at the Harvard School of Engineering and Applied Sciences.

Since their 2010 publication on the human breathing lung-on-a-chip in Science, and with grant support from the Defense Advanced Research Projects Agency (DARPA), Food and Drug Administration (FDA) and National Institutes of Health (NIH), Ingber and his team have developed more than ten different Organs-on-Chip models, including chips that mimic liver, gut, kidney and bone marrow. The DARPA effort also has supported the engineering of the instrument that automates chip operations and fluidically links the different organs-on-chips together to more closely mimic whole body physiology, while permitting high-resolution imaging and molecular analysis.

The transition of the Organs-on-Chips technology to a startup was enabled by the Wyss Institute’s unique technology translation model, which takes lead high-value technologies that emerge from Wyss faculty efforts, and de-risks them both technically and commercially to increase their likelihood for commercial success.

Through numerous collaborations with industry, the Wyss Institute team refined their technology, and validated it for market need and impact by testing existing drugs and modeling various human diseases on-chip. And with an eye towards creating a technology that can be mass-manufactured cost effectively outside the lab, they formed industrial partnerships to achieve this goal and increase the likelihood of success in the marketplace.

Mature Institute projects are led by teams that include the lead faculty member, a technical champion with industrial experience on the Institute’s Advanced Technology Team, and a Wyss business development lead, working closely with Harvard OTD.

The Organs-on-Chips project leaders included Don Ingber, Geraldine Hamilton, PhD, Lead Senior Scientist on the Wyss Institute Biomimetics Microsystems Platform, and James Coon, a Wyss Institute Entrepreneur-in-Residence. Hamilton and Coon will be moving to take senior leadership positions at Emulate, along with multiple members of the research team, smoothing the transition from academia to industry.

“The ‘Organs-on-Chips’ story is a great example of how the Wyss Institute brings researchers with industrial experience into the heart of our research community and effectively bridges academia and industry,” said Alan Garber, Provost of Harvard University and Chair of the Institute’s Board of Directors.

Source: Harvard Univ.

Molecular Dynanmics: Visualizing the Invisible

Panagiotis Grammatikopoulos in the OIST Nanoparticles by Design Unit simulates the interactions of particles that are too small to see, and too complicated to visualize. In order to study the particles’ behavior, he uses a technique called molecular dynamics.

This means that every trillionth of a second, he calculates the location of each individual atom in the particle based on where it is and which forces apply. He uses a computer program to make the calculations, and then animates the motion of the atoms using visualization software. The resulting animation illuminates what happens, atom-by-atom, when two nanoparticles collide. Grammatikopoulos calls this a virtual experiment.

He knows what the atoms in his starting nanoparticles look like. He knows their motion follows the laws of Newtonian physics. His colleagues have seen what the resulting particles look like after collision experiments. Once his simulation is complete, Grammatikopoulos compares his end products with his colleagues to check his accuracy. Grammatikopoulos most recently simulated how palladium nanoparticles interact, published in Scientific Reports on July 22, 2014 (“Coalescence-induced crystallisation wave in Pd nanoparticles”).

 

Grammatikopoulos simulated two palladium nanoparticles colliding at different temperatures. The hotter the temperature, the more homogenous the resulting product, and the further the atoms in the particle crystallize. (click on image to enlarge)

Palladium is an expensive but highly efficient catalyst that lowers the energy required to start many chemical reactions. Researchers can make palladium even more efficient by designing palladium nanoparticles, which use the same mass of palladium in tinier pieces, increasing surface area. The more surface area a catalyst has, the more effective it is, because there are more active sites where elements can meet and reactions can occur.

However, shrinking a material to only a few nanometers can change some of the properties of that material. For example, all nanoparticles melt at cooler temperatures than they would normally, which changes what happens when two particles collide. Ordinarily, two particles will collide and release a small amount of heat, but the particles remain more or less the same. But when two nanoparticles collide, sometimes the heat released melts the surface of the two particles, and they fuse together.

Palladium Crystallization at 300K. Grammatikopoulos created this simulation of palladium nanoparticles colliding at 300 Kevin, or about 27 degrees Celsius. The nanoparticles meet, then fuse, then crystallize in orderly planes.

Grammatikopoulos simulated palladium nanoparticles colliding and fusing at different temperatures. He determined that each time the particles fused, their atoms would start to crystallize into orderly rows and planes. At higher temperatures, the particles fuse into one homogeneous structure. At lower temperatures, the products look like classic snowmen, with a few parts that had crystallized with different orientations.

“The simulation gives you an understanding of physical processes,” said Grammatikopoulos. Before his research, Grammatikopoulos could not explain why all the palladium nanoparticles his lab created had a crystalline structure. Furthermore, he noticed that many palladium nanoparticles grew protrusions, giving the particles a lumpy shape. “Since the protrusions stick out, they bond more easily with other molecules,” Grammatikopoulos explained. “I’m not sure yet if it’s beneficial, but it’s definitely affecting the catalytic properties.”

Palladium Crystallization at 1000K. Grammatikopoulos created this simulation of palladium nanoparticles colliding at 1000 Kevin, or about 727 degrees Celsius. At this hot temperature, the nanoparticles meet, fuse, and crystallize, forming one large homogenous product.

This study establishes some ground rules and explains certain properties of palladium nanoparticles. Understanding these properties could help design other nanoparticles out of other materials that would rival palladium’s abilities as a catalyst. Palladium plays a role in thousands of important reactions, from making drugs to creating new biofuels. For example, Prof. Mukhles Sowwan’s Nanoparticles by Design Unit and Prof. Igor Goryanin’s Biological Systems Unit at OIST are working with palladium-catalyzed reactions to improve the efficiency of microbial fuel cells. Better palladium nanoparticles will propel this research forward.

“We need to understand the basic science,” explained Sowwan, who is Grammatikopoulos’ advisor. Sowwan says that the field of nanoscience is only starting to move towards applying the research, because there is still so much to learn about the properties of nanoparticles. “If you build something without understanding the basics,” Sowwan said, “you will not be able to explain the results.”

Source: By Poncie Rutsch, Okinawa Institute of Science and Technology