#Eco-friendly'prefab nanoparticles'could revolutionize nano manufacturing A team of materials chemists polymer scientists device physicists
and others at the University of Massachusetts Amherst today report a breakthrough technique for controlling molecular assembly of nanoparticles over multiple length scales that should allow faster cheaper more ecologically friendly manufacture of organic photovoltaics and other electronic devices.
Details are in the current issue of Nano Letters. Lead investigator chemist Dhandapani Venkataraman points out that the new techniques successfully address two major goals for device manufacture:
controlling molecular assembly and avoiding toxic solvents like chlorobenzene. Now we have a rational way of controlling this assembly in a water-based system he says.
It's a completely new way to look at problems. With this technique we can force it into the exact structure that you want.
Materials chemist Paul Lahti co-director with Thomas Russell of UMASS Amherst's Energy Frontiers Research center (EFRC) supported by the U s. Department of energy says One of the big implications of this work
is that it goes well beyond organic photovoltaics or solar cells where this advance is being applied right now.
Looking at the bigger picture this technique offers a very promising flexible and ecologically friendly new approach to assembling materials to make device structures.
Lahti likens the UMASS Amherst team's advance in materials science to the kind of benefits the construction industry saw with prefabricated building units.
This strategy is right along that general philosophical line he says. Our group discovered a way to use sphere packing to get all sorts of materials to behave themselves in a water solution before they are sprayed onto surfaces in thin layers and assembled into a module.
We are preassembling some basic building blocks with a few predictable characteristics which are then available to build your complex device.
and we've shown that it works. The new method should reduce the time nano manufacturing firms spend in trial-and-error searches for materials to make electronic devices such as solar cells organic transistors and organic light-emitting diodes.
The old way can take years Lahti says. Another of our main objectives is to make something that can be scaled up from nano-to mesoscale
For photovoltaics Venkataraman points out The next thing is to make devices with other polymers coming along to increase power conversion efficiency
He suggests that reaching 5 percent power conversion efficiency would justify the investment for making small flexible solar panels to power devices such as smart phones.
and all 307 million United states users switched from batteries to flexible solar it could save more than 1500 megawatts per year.
That's nearly the output of a nuclear power station Venkataraman says and it's more dramatic
when you consider that coal fired power plants generate 1 megawatt and release 2250 lbs. of carbon dioxide. So if a fraction of the 6. 6 billion mobile phone users globally changed to solar it would reduce our carbon footprint a lot.
Doctoral student and first author Tim Gehan says that organic solar cells made in this way can be semitransparent as well so you could replace tinted windows in a skyscraper
and have them all producing electricity during the day when it's needed. And processing is much cheaper and cleaner with our cells than in traditional methods.
Venkataraman credits organic materials chemist Gehan with postdoctoral fellow and device physicist Monojit Bag with making crucial observations and using persistent detective work to get past various roadblocks in the experiments.
These two were outstanding in helping this story move ahead he notes. For their part Gehan and Bag say they got critical help from the Amherst Fire department
It was Bag who put similar sized and charged nanoparticles together to form a building block then used an artist's airbrush to spray layers of electrical circuits atop each other to create a solar-powered device.
He says Here we preformed structures at nanoscale so they will form a known structure assembled at the meso scale from
Scientists develop pioneering new spray-on solar cells More information: Nano Letters pubs. acs. org/doi/pdf/10.1021/nl502209 9
#Magnetic nanoparticles break the capacity barrier for antibody purification Monoclonal antibodies represent the largest and fastest-growing segment of international biopharma.
While these therapeutic agents are a boon for global healthcare productivity constraints pose a serious challenge for manufacturers seeking to make sufficient amounts for therapeutic applications.
Now A*STAR researchers have developed a high-capacity method to purify monoclonal antibodies that uses magnetic nanoparticles and also introduces new operating conditions.
At present therapeutic antibodies are purified generally by a technique known as protein A affinity chromatography. The process yields a high purification factorypically 99 per centut it is slow thereby creating a severe productivity bottleneck.
The process is hindered largely by the low capacity of protein A which binds monoclonal antibodies at an average rate of 50 grams per liter of protein A chromatography media.
The overall purification process requires unpurified antibodies to pass through columns packed with the media in multiple cycles that can take up to a week.
A research team led by Pete Gagnon and co-workers from the A*STAR Bioprocessing Technology Institute in Singapore have developed an alternative method with 1000 times the capacity of protein A. The technique involves the use of polyethylene glycol
which causes the antibodies to be deposited on the surface of starch-coated magnetic nanoparticles (see image).
The particles are collected in a magnetic field undeposited contaminants are washed away and the purified antibodies recovered by removing the polyethylene glycol.
The high capacity of our nanoparticle method makes it much faster than column chromatography explains Gagnon.
Instead of the pharmaceutical industry norm of five to eight cycles the new process requires only one cycle
Polyethylene glycol has been used for decades to process antibodies but it has achieved never the level of purity needed for clinical therapeutics.
The team discovered that by elevating the salt concentration they could reduce contaminant levels from about 250000 parts per million to 500:
the same level achieved by protein A a single follow-on polishing step using a multimodal chromatography column further purified the antibodies to clinical quality standards.
In addition to solving the longstanding problem of productivity for monoclonal antibodies the nanoparticle approach can be applied to many other therapeutic proteins and also to viral vaccines.
Gagnon P. Toh P. & Lee J. High productivity purification of Immunoglobulin g monoclonal antibodies on starch-coated magnetic nanoparticles by steric exclusion of polyethylene glycol.
Journal of Chromatography A 1324 17180 (2013. dx. doi. org/10.1016/j. chroma. 2013.11.03 3
#Pentagonal nanorods show catalytic promise Pentagonal nanorods have a unique morphology that confers interesting compositional
and high catalytic activity that make them excellent candidates for industrial catalysts. Now, researchers in Singapore have developed a simple chemical process to grow uniform pentagonal nanorods composed of gold and copper.
These new materials readily catalyze the direct alkylation of an amine with an alcohol, rendering them useful in the fields of materials chemistry and nanotechnology."
"We successfully synthesized goldopper pentagonal nanorods with controlled size and composition by a seed-mediated growth route,"explains lead researcher Jackie Ying from the A*STAR Institute of Bioengineering and Nanotechnology.
The'seeds'are multiple crystals of elongated gold decahedrons, joined together by shared facesn arrangement known as multiply-twinning.
To create the nanorods, the team placed the gold seeds in a solution containing a copper precursor and applied heat a process that produced nearly uniform pentagonal nanorods.
Ying's team showed that they could control the length of these nanorods by changing the amount of gold seeds added to the copper precursor.
Adding a 1: 1 ratio of gold to copper produced nanorods that grew approximately 15 nanometers in length while a 1: 2 ratio produced nanorods approximately 19 nanometers long,
and a 1: 3 ratio produced nanorods approximately 24 nanometers long. The diameter of the nanorods remained the same,
however, regardless of the ratio of metals used. The ability to control the size and composition of the nanorods means it is easier to control the properties of the bimetallic goldopper nanoparticles compared to nanoparticles made of just one metal,
Yang explains. Next, the team evaluated the catalytic activity of these goldopper nanorods in a carbonitrogen-bond-forming reactionhe direct alkylation of an amine using an alcohol."
"This hydrogen-borrowing strategy is an attractive synthetic method for the C bond formation as it is an environmentally friendly process
which produces only water as a byproduct, "says Ying. The nanorods were examined as catalysts for this reaction using the model substrates p-toluene sulphonamide and benzyl alcohol."
"Our heterogeneous catalyst showed higher catalytic activity toward the C coupling reaction and better recyclability compared to commercially available catalysts,
"Ying says. Beyond catalysis, Ying predicts these new materials could be useful in electronics, chemical sensing and even biomedicine.
Her team now plans to use the nanorods as seeds themselves to synthesize nanoparticles comprised of a goldopper core surrounded by a shell of another material, such as platinum, for energy applications
#Watching molecules'dance'in real time (Phys. org) A new technique which traps light at the nanoscale to enable real-time monitoring of individual molecules bending
and flexing may aid in our understanding of how changes within a cell can lead to diseases such as cancer.
A new method which uses tightly confined light trapped between gold mirrors a billionth of a metre apart to watch molecules'dancing'in real time could help researchers uncover many of the cell processes that are essential to all life
and how small changes to these processes can lead to diseases such as cancer or Alzheimer's. Researchers from the University of Cambridge have demonstrated how to use light to view individual molecules bending
and flexing as they move through a model cell membrane in order to better understand the inner workings of cells.
Details are published today (12 august) in the journal Scientific Reports. The membrane is vital to the normal functioning of cells;
keeping viruses out but allowing select molecules such as drugs to get through. This critical front line of cellular defence is made up of a layer of fatty lipids just a few nanometres thick.
When the cell membrane is damaged however unwanted invaders can march into the cell. Many degenerative diseases such as Alzheimer's Parkinson's cystic fibrosis and muscular dystrophy are believed to originate from damage to the cell membrane.
The ability to watch how individual lipid molecules interact with their environment can help researchers understand not only how these
and other diseases behave at their earliest stages but also many of the fundamental biological processes which are key to all life.
In order to view the behaviour of the cell membrane at the level of individual molecules the Cambridge team working with researchers from the University of Leeds squeezed them into a tiny gap between the mirrored gold facets of a nanoparticle sitting just above a flat gold surface.
Through highly precise control of the geometry of the nanostructures and using Raman spectroscopy an ultra-sensitive molecular identification technique the light can be trapped between the mirrors allowing the researchers to'fingerprint'individual molecules.
It's like having an extremely powerful magnifying glass made out of gold said Professor Jeremy Baumberg of the Nanophotonics Centre at Cambridge's Cavendish Laboratory who led the research.
Analysing the colours of the light which is scattered by the mirrors allowed the different vibrations of each molecule to be seen within this intense optical field.
Probing such delicate biological samples with light allows us to watch these dancing molecules for hours without changing
or destroying them said co-author Felix Benz. The molecules stand shoulder to shoulder like trees in a forest while a few jitter around sideways.
By continuously observing the scattered light individual molecules are seen moving in and out of the tiny gaps between the mirrors.
Carefully analysis of the signatures from different parts of each molecule allowed any changes in the molecule shape to be observed
which helps to understand how their reaction sites can be uncovered when they are at work. Most excitingly the team says these flexing
The new insights from this work suggest ways to unveil processes which are essential to all life
and understand how small changes to these processes can cause disease. Explore further: Synthetic molecule makes cancer self-destruc c
#Mobile phones come alive with the sound of music thanks to nanogenerators Charging mobile phones with sound, like chants from at football ground, could become a reality, according to a new collaboration between scientists from Queen Mary University of London and Nokia.
Last year, Dr Joe Briscoe and Dr Steve Dunn from QMUL's School of engineering and Materials science found that playing pop
and rock music improves the performance of solar cells, in research published with Imperial College London. Developing this research further,
Nokia worked with the QMUL team to create an energy harvesting prototype (a nanogenerator) that could be used to charge a mobile phone using everyday background noise such as traffic,
music, and our own voices. The team used the key properties of zinc oxide, a material that when squashed
or stretched creates a voltage by converting energy from motion into electrical energy, in the form of nanorods.
The nanorods can be coated onto various surfaces in different locations making the energy harvesting quite versatile.
When this surface is squashed or stretched, the nanorods then generate a high voltage. The nanorods respond to vibration
and movement created by everyday sound, such as our voices. Electrical contacts on both sides of the rods are used then to harvest the voltage to charge a Phone in order to make it possible to produce these nanogenerators at scale
the scientists found innovative ways to cut costs in the production process. Firstly, they developed a process
whereby they could spray on the nanorod chemicals almost like nanorod graffiti to cover a plastic sheet in a layer of zinc oxide.
When put into a mixture of chemicals and heated to just 90°C, the nanorods grew all over the surface of the sheet.
Secondly, gold is used traditionally as an electrical contact but the team were able to produce a method of using cheap and cheerful aluminium foil instead.
The ultimate device was the same size as a Nokia Lumina 925 and generates five volts,
which is enough to charge a phone. Could plugging your phone into the mains socket be a thing of past?
Dr Joe Briscoe commented:""Being able to keep mobile devices working for longer, or do away with batteries completely by tapping into the stray energy that is all around us is an exciting concept.
This collaboration was an excellent opportunity to develop alternative device designs using cheap and scalable methods.
We hope that we have brought this technology closer to viability. a
#An inkjet-printed field-effect transistor for label-free biosensing Thin-film transistors (TFTS) are powerful devices in semiconductor manufacturing
and form the basis of countless electronic devices such as memory chips photovoltaic cells logic gates and sensors. An interesting alternative to inorganic TFTS (silicon) is organic TFTS (OTFTS)
which offer the possibility of mass production by using the conventional printing technology and working with low-cost materials.
However numerous inherent problems still remain especially concerning the long-term stability and lack of reliability.
Researchers from the Institut Català de Nanociència i Nanotecnologia's (ICN2 Catalan Institute of Nanoscience and Nanotechnology) Nanobioelectronics and Biosensors Group led by the ICREA Research Prof Arben Merkoçi work
to get OTFTS closer to devices which can be applied fully in field applications. The Group published in the last issue of Advanced Functional Materials an article describing a flexible biological field-effect transistor (Biofet) for use in biosensing.
The fabrication structure materials optimization electrical characteristics and functionality of the starting OTFT and final Biofet are discussed also.
The authors of the article are Dr Mariana Medina-Sánchez Dr Carme Martínez-Domingo Dr Eloi Ramon and ICREA Research Prof Arben Merkoçi.
It was made by inkjet printing of an organic field-effect transistor (OFET) and subsequent functionalization of the insulator with specific antibodies.
The Biofet designed at ICN2 represents an important starting point for the design and fabrication of flexible organic biosensing devices by inkjet printing.
The authors are confident that once this technology has matured it will be amenable to miniaturization for integration into a fully functional device for point-of-care diagnosis. Explore further:
Formation of organic thin-film transistors through room-temperature printing More information: Mariana Medina-Sánchez Carme Martínez-Domingo Eloi Ramon Arben Merkoçi.
An Inkjet-Printed Field-Effect Transistor for Label-Free Biosensing. Advanced Functional Materials. Article first published online:
#New graphene framework bridges gap between traditional capacitors batteries Researchers at the California Nanosystems Institute (CNSI) at UCLA have set the stage for a watershed in mobile energy storage by using a special graphene material
to significantly boost the energy density of electrochemical capacitors, putting them on a par with lead acid batteries.
The material, called a holey graphene framework, has perforated a three-dimensional structure characterized by tiny holes;
it not only increases energy density (the amount of energy stored and ready for use) but allows electrochemical capacitors to maintain their high power density (the amount of power per unit of mass or volume), according to Xiangfeng Duan,
a UCLA professor of chemistry and biochemistry who led the research. Electrochemical capacitors, also known as ECS or supercapacitors, are an important technology for the future of energy storage and mobile power supplies,
but they have been limited by low energy density. Compared with traditional batteries, ECS typically have superior power density
and cycle lifehe number of complete chargeischarge cycles an energy source can support before it decreases to 80 percent of its original capacity
and is considered"worn out.""But they have had energy density of at least one order of magnitude below batteries. Because the main component of an EC is its electrode material,
which is responsible for the EC's overall performance, recent research has focused on efficient new materials that are able to increase energy density without sacrificing power density or cycle life.
A high-performance EC electrode must have high electrical conductivity, a high ion-accessible surface area, a high ionic transport rate and high electrochemical stability.
Current state-of-the-art ECS generally use porous activated carbon electrodes with energy densities much lower than lead acid batteries to 5 watt hours per kilogram vs. 25 to 35 watt hours per kilogram (5
to 7 watt hours per liter vs 50 to 90 watt hours per liter. In their study, published online August 8 in the journal Nature Communications, the CNSI researchers led by Duan used a highly interconnected 3d holey graphene framework as the electrode material to create an EC with unprecedented performance.
The electrode demonstrates superior electrical conductivity, exceptional mechanical flexibility and unique hierarchical porosity, ensuring the efficient transport of electrons
and ions and enabling the highest gravimetric energy densities of 127 watt hours per kilogram and volumetric energy density of 90 watt hours per liter.
Furthermore, the team has shown that a fully packaged EC exhibits unparalleled energy densities of 35 watt hours per kilogram (49 watt hours per liter) bout five to 10 times higher than current commercial supercapacitors and on a par
with acid batteries.""The holey grahene EC bridges the energy density gap between traditional capacitors and batteries, yet with vastly higher power density,"Duan said."
"It creates exciting opportunities for mobile power supplies for many applications from cell phones to electric vehicles. v
#On the frontiers of cyborg science No longer just fantastical fodder for sci-fi buffs, cyborg technology is bringing us tangible progress toward real-life electronic skin, prosthetics and ultraflexible circuits.
Now taking this human-machine concept to an unprecedented level, pioneering scientists are working on the seamless marriage between electronics
and brain signaling with the potential to transform our understanding of how the brain worksnd how to treat its most devastating diseases.
Their presentation is taking place at the 248th National Meeting & Exposition of the American Chemical Society (ACS), the world's largest scientific society."
"By focusing on the nanoelectronic connections between cells, we can do things no one has done before,
"says Charles M. Lieber, Ph d."We're really going into a new size regime for not only the device that records
or stimulates cellular activity, but also for the whole circuit. We can make it really look and behave like smart, soft biological material,
and integrate it with cells and cellular networks at the whole-tissue level. This could get around a lot of serious health problems in neurodegenerative diseases in the future."
"These disorders, such as Parkinson's, that involve malfunctioning nerve cells can lead to difficulty with the most mundane and essential movements that most of us take for granted:
walking, talking, eating and swallowing. Scientists are working furiously to get to the bottom of neurological disorders.
But they involve the body's most complex organhe brainhich is largely inaccessible to detailed, real-time scrutiny.
This inability to see what's happening in the body's command center hinders the development of effective treatments for diseases that stem from it.
By using nanoelectronics, it could become possible for scientists to peer for the first time inside cells, see what's going wrong in real time
and ideally set them on a functional path again. For the past several years Lieber has been working to dramatically shrink cyborg science to a level that's thousands of times smaller and more flexible than other bioelectronic research efforts.
His team has made ultrathin nanowires that can monitor and influence what goes on inside cells.
which are affected in some neurodegenerative diseases. And it's at this level where the promise of Lieber's most recent work enters the picture.
In one of the lab's latest directions, Lieber's team is figuring out how to inject their tiny,
ultraflexible electronics into the brain and allow them to become fully integrated with the existing biological web of neurons.
"It's hard to say where this work will take us, "he says.""But in the end,
#Stronger better solar cells: Graphene research on the cusp of new energy capabilities (Phys. org) There remains a lot to learn on the frontiers of solar power research particularly
when it comes to new advanced materials which could change how we harness energy. Under the guidance of Canada Research Chair in Materials science with Synchrotron radiation Dr. Alexander Moewes University of Saskatchewan researcher Adrian Hunt spent his Phd investigating graphene oxide a cutting-edge material that he hopes will shape the future
of technology. To understand graphene oxide it is best to start with pure graphene which is a single-layer sheet of carbon atoms in a honeycomb lattice that was made first in 2004 by Andre Geim
and Kostya Novoselov at the University of Manchester a discovery that earned the two physicists a Nobel prize in 2010.
It is incredibly thin therefore it is incredibly transparent. It also has extremely high conductivity it's much better than copper
and it's extremely strong its tensile strength is even stronger than steel Hunt said. Air doesn't damage it.
It can't corrode it can't degrade. It's really stable. All of this makes graphene a great candidate for solar cells.
In particular its transparency and conductivity mean that it solves two problems of solar cells: first light needs a good conductor
in order to get converted into usable energy; secondly the cell also has to be transparent for light to get through.
Most solar cells on the market use indium tin oxide with a nonconductive glass protective layer to meet their needs.
Indium is extremely rare so it is becoming more expensive all the time. It's the factor that will keep solar cells expensive in the future
whereas graphene could be very cheap. Carbon is said abundant Hunt. Although graphene is a great conductor it is not very good at collecting the electrical current produced inside the solar cell
which is why researchers like Hunt are investigating ways to modify graphene to make it more useful.
Whether or not it will solve the solar panel problem is yet to be seen and researchers in the field are building up their understanding of how the new material works.
Using X-ray scattering techniques at the REIXS and SGM beamlines at the Canadian Light source as well as a Beamline 8. 0. 1 at the Advanced Light source Hunt set out to learn more about how oxide groups attached to the graphene lattice changed it
Each different part of the graphene oxide has a unique electronic signature. Using the synchrotron Hunt could measure where electrons were on the graphene
It's a pitfall that could be important to understand in the development of long-lasting solar cells where sun could provide risky heat into the equation.
#Used-cigarette butts offer energy storage solution A group of scientists from South korea have converted used-cigarette butts into a high-performing material that could be integrated into computers handheld devices electrical vehicles and wind turbines to store energy.
Presenting their findings today 5 august 2014 in the journal Nanotechnology the researchers have demonstrated the material's superior performance compared to commercially available carbon graphene and carbon nanotubes.
It is hoped the material can be used to coat the electrodes of supercapacitorslectrochemical components that can store extremely large amounts of electrical energyhilst also offering a solution to the growing environmental problem caused by used-cigarette filters.
or 766571 metric tons are deposited into the environment worldwide every year. Co-author of the study Professor Jongheop Yi from Seoul National University said:
Our study has shown that used-cigarette filters can be transformed into a high-performing carbon-based material using a simple one step process
which simultaneously offers a green solution to meeting the energy demands of society. Numerous countries are developing strict regulations to avoid the trillions of toxic and non-biodegradable used-cigarette filters that are disposed of into the environment each yearur method is just one way of achieving this.
Carbon is the most popular material that supercapacitors are composed of due to its low cost high surface area high electrical conductivity and long term stability.
Scientists around the world are currently working towards improving the characteristics of supercapacitorsuch as energy density power density
and cycle stabilityhilst also trying to reduce production costs In their study the researchers demonstrated that the cellulose acetate fibres that cigarette filters are composed mostly of could be transformed into a carbon-based material using a simple one-step burning technique called pyrolysis.
A high-performing supercapacitor material should have a large surface area which can be achieved by incorporating a large number of small pores into the material continued Professor Yi.
A combination of different pore sizes ensures that the material has high power densities which is an essential property in a supercapacitor for the fast charging
and discharging. Once fabricated the carbon-based material was attached to an electrode and tested in a three-electrode system to see how well the material could adsorb electrolyte ions (charge) and then release electrolyte ions (discharge).
The material stored a higher amount of electrical energy than commercially available carbon and also had a higher amount of storage compared to graphene
and carbon nanotubes as reported in previous studies. Explore further: Nano-supercapacitors for electric cars More information:
Preparation of energy storage material derived from a used cigarette filter for a supercapacitor electrode Nanotechnology iopscience. iop. org/0957-4484/25/34/345601 5
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