Research creates nanoparticles perfectly formed to tackle cancer

Researchers from the University of Hull have discovered a way to load up nanoparticles with large numbers of light-sensitive molecules to create a more effective form of photodynamic therapy (PDT) for treating cancer.

Photodynamic therapy uses molecules which, when irradiated with light, cause irreparable damage to cells by creating toxic forms of oxygen, called reactive oxygen species. Most PDT works with individual light-sensitive molecules -- but the new nanoparticles could each carry hundreds of molecules to a cancer site.

A number of different light-sensitive molecules -- collectively known as photosensitisers -- are used in PDT and each absorbs a very specific part of the light spectrum. The research team -- from the University of Hull's Department of Chemistry -- placed one kind of photosensitiser inside each nanoparticle and another on the outside, which meant that far more reactive oxygen species could be created from the same amount of light. The findings are published in the current issue of Molecular Pharmaceutics.

The nanoparticles have also been designed to be the perfect size and shape to penetrate easily into the tumour, as lead researcher, Dr Ross Boyle, explains.

"Small cancer tumours get nutrients and oxygen by diffusion, but once tumours reach a certain size, they need to create blood vessels to continue growing, " he says. "These new blood vessels, or neovasculature, are 'leaky' because the vessel walls are not as tightly knit as normal blood vessels. Our nanoparticles have been designed so the pressure in the blood vessels will push them through the space between the cells to get into the tumour tissue."

The nanoparticles are made from a material that limits the leaching of its contents while in the bloodstream, but when activated with light, at the tumour, the toxic reactive oxygen species can diffuse freely out of the particles; meaning that damage is confined to the area of the cancer.

The researchers tested the nanoparticles on colon cancer cells, and while they were able to penetrate the cells, they also found that the nanoparticles could still be effective when near -- rather than inside -- the cancer cells.

"Some types of cancer cell are able to expel conventional drugs, so if we can make this kind of therapy work simply by getting the nanoparticles between the cancer cells, rather than inside them, it could be very beneficial," says Dr Boyle.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by University of Hull.

Journal Reference:

Maheshika Kuruppuarachchi, Huguette Savoie, Ann Lowry, Cristina Alonso, and Ross W. Boyle. Polyacrylamide Nanoparticles as a Delivery System in Photodynamic Therapy. Molecular Pharmaceutics, 2011; 110316145246004 DOI: 10.1021/mp200023y

Making complex fluids look simple

An international research team has successfully developed a widely applicable method for discovering the physical foundations of complex fluids for the first time. Researchers at the University of Vienna and University of Rome have developed a microscopic theory that describes the interactions between the various components of a complex polymer mixture. This approach has now been experimentally proven by physicists from Jülich, who conducted neutron scattering experiments in Grenoble.

The results have been published in the June issue of the journal Physical Review Letters.

Some important materials from technology and nature are complex fluids: polymer melts for plastics production, mixtures of water, oil and amphiphiles, which can be found in both living cells and in your washing machine, or colloidal suspensions such as blood or dispersion paints. They are quite different from simple fluids consisting of small molecules, such as water, because they are made of mixtures of particles between a nanometre and a micrometre in size, and have a large number of so-called degrees of freedom. The latter include vibrations, movements of the functional groups of molecules or joint movements of several molecules. They can appear on widely varied length, time, and energy scales. This makes experimental and theoretical studies difficult and, so far, has impeded understanding of the properties of these systems and the targeted development of new materials with improved properties.

A method developed and tested by physicists at Forschungszentrum Jülich, the Institut Laue-Langevin in Grenoble, and the Universities of Vienna and Rome now permits realistic modelling of complex fluids for the first time. "Our microscopic theory describes the interactions between the various components of a complex mixture and in turn, enables us to draw realistic conclusions about their macroscopic properties, such as their structure or their flow properties," said Prof. Christos Likos of the University of Vienna, an expert on theory and simulation.

The team from Vienna and Rome developed the theory model. Since the researchers were unable to include all the details of the real system -- a mixture of larger star-shaped polymers and smaller polymer chains -- they systematically eliminated the rapidly moving degrees of freedom and focused on the relevant slow degrees of freedom, a time-consuming and challenging task. "To do this, we use a relatively new method called coarse graining and replace each complex macromolecule with a sphere of the appropriate size. The challenge involves integrating the degrees of freedom that have been eliminated in the simplified systems as averages so that the characteristics of the substances are retained," Likos explained.

The team from Jülich used elaborate small angle neutron scattering experiments with the instrument D11 at the Institut Laue-Langevin in Grenoble to prove that the interactions between the spheres of the coarse-grained model realistically simulate the conditions in the real system. "We were faced with the proverbial challenge of visualizing the needle in a haystack," explained Dr. Jörg Stellbrink, a physicist and neutron scattering expert at the Jülich Centre for Neutron Science (JCNS). For neutrons, the individual polymers of the mixture cannot be readily distinguished. For this reason, the physicists "coloured" the components they were interested in, so that they stood out of the crowd. This is one of the Jülich team's specialities. In this way, they were able to selectively examine the structures and interactions on a microscopic length scale.

The physicists are especially proud of the excellent agreement between theoretical predictions and experimental results. The method will now open up a spectrum of possibilities for studying the physical properties of a whole range of different complex mixtures.

Story Source:

The above story is reprinted (with editorial adaptations ) from materials provided by Helmholtz Association of German Research Centres, via EurekAlert!, a service of AAAS.

Journal Reference:

B. Lonetti, M. Camargo, J. Stellbrink, C. Likos, E. Zaccarelli, L. Willner, P. Lindner, D. Richter. Ultrasoft Colloid-Polymer Mixtures: Structure and Phase Diagram. Physical Review Letters, 2011; 106 (22) DOI: 10.1103/PhysRevLett.106.228301

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Applying conductive nanocoatings to textiles

ScienceDaily (June 6, 2011) — Imagine plugging a USB port into a sheet of paper, and turning it into a tablet computer. It might be a stretch, but ideas like this have researchers at North Carolina State University examining the use of conductive nanocoatings on simple textiles -- like woven cotton or even a sheet of paper.

"Normally, conductive nanocoatings are applied to inorganic materials like silicon. If we can find a way to apply them to textiles -- cheap, flexible materials with a contorted surface texture -- it would represent a cost-effective approach and framework for improving current and future types of electronic devices," says Dr. Jesse Jur, assistant professor of textile engineering, chemistry and science, and lead author of a paper describing the research.

Using a technique called atomic layer deposition, coatings of inorganic materials, typically used in devices such as solar cells, sensors and microelectronics, were grown on the surface of textiles like woven cotton and nonwoven polypropylene -- the same material that goes into reusable grocery store bags. "Imagine coating a textile fabric so that each fiber has the same nanoscale-thick coating that is thousands of times thinner than a human hair -- that's what atomic layer deposition is capable of doing," Jur says. The research, done in collaboration with the laboratory of Dr. Gregory Parsons, NC State Alcoa Professor of Chemical and Biomolecular Engineering, shows that common textile materials can be used for complex electronic devices.

As part of their study, the researchers created a procedure to quantify effective electrical conductivity of conductive coatings on textile materials. The current standard of measuring conductivity uses a four-point probe that applies a current between two probes and senses a voltage between the other two probes. However, these probes were too small and would not give the most accurate reading for measurements on textiles. In the paper, researchers describe a new technique using larger probes that accurately measures the conductivity of the nanocoating. This new system gives researchers a better understanding of how to apply coatings on textiles to turn them into conductive devices.

"We're not expecting to make complex transistors with cotton, but there are simple electronic devices that could benefit by using the lightweight flexibility that some textile materials provide," Jur explains. "Research like this has potential health and monitoring applications since we could potentially create a uniform with cloth sensors embedded in the actual material that could track heart rate, body temperature, movement and more in real time. To do this now, you would need to stick a bunch of wires throughout the fabric -- which would make it bulky and uncomfortable.

"In the world of electronics, smaller and more lightweight is always the ideal. If we can improve the process of how to apply and measure conductive coatings on textiles, we may move the needle in creating devices that have the requisite conductive properties, with all the benefits that using natural textile materials affords us," Jur says.

A paper describing the research is published in the June issue of Advanced Functional Materials. Fellow NC State researchers include Parsons, post-doctoral researcher Christopher Oldham, and graduate student William Sweet. Funding for the study came from the Department of Energy and the Nonwovens Cooperative Research Center.

Story Source:

The above story is reprinted (with editorial adaptations by ScienceDaily staff) from materials provided by North Carolina State University.

Journal Reference:

Jesse. S. Jur, William J. Sweet III, Christopher J. Oldham and Gregory N. Parsons. Atomic Layer Deposition of Conductive Coatings on Cotton, Paper, and Synthetic Fibers: Conductivity Analysis and Functional Chemical Sensing Using ‘All-Fiber’ Capacitors. Advanced Functional Materials, June, 2011 DOI: 10.1002/adfm.201190035

Note: If no author is given, the source is cited instead.

Disclaimer: Views expressed in this article do not necessarily reflect those of ScienceDaily or its staff.

Scientists detect Earth-equivalent amount of water within the moon

 There is water inside the moon – so much, in fact, that in some places it rivals the amount of water found within the Earth.

The finding from a scientific team including Brown University comes from the first-ever measurements of water in lunar melt inclusions. Those measurements show that some parts of the lunar mantle have as much water as the Earth's upper mantle.

Lunar melt inclusions are tiny globules of molten rock trapped within crystals that are found in volcanic glass deposits formed during explosive eruptions. The new finding, published in Science Express, shows lunar magma water contents 100 times higher than previous studies have suggested.

The result is the culmination of years of investigation by the team searching for water and other volatiles in volcanic glasses returned by NASA Apollo missions in the late 1960s and early 1970s. In a paper in Nature in 2008, the same team led by Alberto Saal, associate professor of geological sciences at Brown, reported the first evidence for the presence of water and used models to estimate how much water was originally in the magmas before eruption.

"The bottom line," said Saal, an author on the Science Express paper and the principal investigator on the research grants, "is that in 2008, we said the primitive water content in the lunar magmas should be similar to the water content in lavas coming from the Earth's depleted upper mantle. Now, we have proven that is indeed the case."

The new finding got a critical assist from a Brown undergraduate student, Thomas Weinreich, who found the melt inclusions that allowed the team to measure the pre-eruption concentration of water in the magma and to estimate the amount of water in the Moon's interior. In a classic needle-in-the-haystack effort, Weinreich searched through thousands of grains from the famous high-titanium "orange soil" discovered by astronaut Harrison Schmitt during the Apollo 17 mission before finding ten that included melt inclusions.

"It just looks like a clear sample with some black specks in it," said Weinreich, the second author on the paper.

Compared with meteorites, Earth and the other inner planets of our solar system contain relatively low amounts of water and volatile elements, which were not abundant in the inner solar system during planet formation. The even lower quantities of these volatile elements found on the Moon has long been claimed as evidence that it must have formed following a high-temperature, catastrophic giant impact. But this new research shows that aspects of this theory must be reevaluated.

"Water plays a critical role in determining the tectonic behavior of planetary surfaces, the melting point of planetary interiors and the location and eruptive style of planetary volcanoes," said Erik Hauri, a geochemist with the Carnegie Institution of Washington and lead author of the study. "We can conceive of no sample type that would be more important to return to Earth than these volcanic glass samples ejected by explosive volcanism, which have been mapped not only on the moon but throughout the inner solar system."

The research team measured the water content in the inclusions using a state-of-the-art NanoSIMS 50L ion microprobe.

"In contrast to most volcanic deposits, the melt inclusions are encased in crystals that prevent the escape of water and other volatiles during eruption. These samples provide the best window we have on the amount of water in the interior of the Moon," said James Van Orman of Case Western Reserve University, a member of the science team.

The study also puts a new twist on the origin of water ice detected in craters at the lunar poles by several recent NASA missions. The ice has been attributed to comet and meteor impacts, but it is possible some of this ice could have come from the water released by eruption of lunar magmas.

View the original article here

New method to make sodium ion-based battery cells could lead to better, cheaper batteries for the electrical grid

By adding the right amount of heat, researchers have developed a method that improves the electrical capacity and recharging lifetime of sodium ion rechargeable batteries, which could be a cheaper alternative for large-scale uses such as storing energy on the electrical grid.

To connect solar and wind energy sources to the electrical grid, grid managers require batteries that can store large amounts of energy created at the source. Lithium ion rechargeable batteries -- common in consumer electronics and electric vehicles -- perform well, but are too expensive for widespread use on the grid because many batteries will be needed, and they will likely need to be large. Sodium is the next best choice, but the sodium-sulfur batteries currently in use run at temperatures above 300 degrees Celsius, or three times the temperature of boiling water, making them less energy efficient and safe than batteries that run at ambient temperatures.

Battery developers want the best of both worlds -- to use both inexpensive sodium and use the type of electrodes found in lithium rechargeables. A team of scientists at the Department of Energy's Pacific Northwest National Laboratory and visiting researchers from Wuhan University in Wuhan, China used nanomaterials to make electrodes that can work with sodium, they reported June 3 online in the journal Advanced Materials.

"The sodium-ion battery works at room temperature and uses sodium ions, an ingredient in cooking salt. So it will be much cheaper and safer," said PNNL chemist Jun Liu, who co-led the study with Wuhan University chemist Yuliang Cao.

The electrodes in lithium rechargeables that interest researchers are made of manganese oxide. The atoms in this metal oxide form many holes and tunnels that lithium ions travel through when batteries are being charged or are in use. The free movement of lithium ions allows the battery to hold electricity or release it in a current. But simply replacing the lithium ions with sodium ions is problematic -- sodium ions are 70 percent bigger than lithium ions and don't fit in the crevices as well.

To find a way to make bigger holes in the manganese oxide, PNNL researchers went much much smaller. They turned to nanomaterials -- materials made on the nanometer-sized scale, or about a million times thinner than a dime -- that have surprising properties due to their smallness. For example, the short distances that sodium ions have to travel in nanowires might make the manganese oxide a better electrode in ways unrelated to the size of the tunnels..

To explore, the team mixed two different kinds of manganese oxide atomic building blocks -- one whose atoms arrange themselves in pyramids, and another one whose atoms form an octahedron, a diamond-like structure from two pyramids stuck together at their bases. They expected the final material to have large S-shaped tunnels and smaller five-sided tunnels through which the ions could flow.

After mixing, the team treated the materials with temperatures ranging from 450 to 900 degrees Celsius, then examined the materials and tested which treatment worked best. Using a scanning electron microscope, the team found that different temperatures created material of different quality. Treating the manganese oxide at 750 degrees Celsius created the best crystals: too low and the crystals appeared flakey, too high and the crystals turned into larger flat plates.

Zooming in even more using a transmission electron microscope at EMSL, DOE's Environmental Molecular Sciences Laboratory on PNNL's campus, the team saw that manganese oxide heated to 600 degrees had pockmarks in the nanowires that could impede the sodium ions, but the 750 degree-treated wires looked uniform and very crystalline.

But even the best-looking material is just window-dressing if it doesn't perform well. To find out if it lived up to its good looks, the PNNL-Wuhan team dipped the electrode material in electrolyte, the liquid containing sodium ions that will help the manganese oxide electrodes form a current. Then they charged and discharged the experimental battery cells repeatedly.

The team measured peak capacity at 128 milliAmp hours per gram of electrode material as the experimental battery cell discharged. This result surpassed earlier ones taken by other researchers, one of which achieved peak capacity of 80 milliAmp hours per gram for electrodes made from manganese oxide but with a different production method. The researchers think the lower capacity is due to sodium ions causing structural changes in that manganese oxide that do not occur or occur less frequently in the heat-treated nano-sized material.

In addition to high capacity, the material held up well to cycles of charging and discharging, as would occur in consumer use. Again, the material treated at 750 Celsius performed the best: after 100 cycles of charging-discharging, it lost only 7 percent of its capacity. Material treated at 600 Celsius or 900 Celsius lost about 37 percent and 25 percent, respectively.

Even after 1,000 cycles, the capacity of the 750 Celsius-treated electrodes only dropped about 23 percent. The researchers thought the material performed very well, retaining 77 percent of its initial capacity.

Last, the team charged the experimental cell at different speeds to determine how quickly it could take up electricity. The team found that the faster they charged it, the less electricity it could hold. This suggested to the team that the speed with which sodium ions could diffuse into the manganese oxide limited the battery cell's capacity -- when charged fast, the sodium ions couldn't enter the tunnels fast enough to fill them up.

To compensate for the slow sodium ions, the researchers suggest in the future they make even smaller nanowires to speed up charging and discharging. Grid batteries need fast charging so they can collect as much newly made energy coming from renewable sources as possible. And they need to discharge fast when demands shoots up as consumers turn on their air conditioners and television sets, and plug in their electric vehicles at home.

Such high performing batteries could take the heat off an already taxed electrical power grid.

Story Source:

The above story is reprinted (with editorial adaptations) from materials provided by DOE/Pacific Northwest National Laboratory.

Journal Reference:

Yuliang Cao, Lifen Xiao, Wei Wang, Daiwon Choi, Zimin Nie, Jianguo Yu, Laxmikant V. Saraf, Zhenguo Yang, Jun Liu. Reversible Sodium Ion Insertion in Single Crystalline Manganese Oxide Nanowires with Long Cycle Life. Advanced Materials, 2011; DOI: 10.1002/adma.201100904