#Gold-diamond nanodevice for hyperlocalised cancer therapy: Gold nanorods can be used as remote controlled nanoheaters delivering the right amount of thermal treatment to cancer cells,
thanks to diamond nanocrystals used as temperature sensors Abstract: Precise targeting biological molecules, such as cancer cells,
for treatment is a challenge, due to their sheer size. Now, Taiwanese scientists have proposed an advanced solution, based on a novel combination of previously used techniques,
which can potentially be applied to thermal cancer therapy. Pei-Chang Tsai from the Institute of Atomic and Molecular Sciences, at the Academia Sinica, Taipei,
and colleagues just published in EPJ QT an improved sensing technique for nanometre scale heating and temperature sensing.
Using a chemical method to attach gold nanorods to the surface of a diamond nanocrystal, the authors have invented a new biocompatible nanodevice.
It is capable of delivering extremely localised heating from a near-infrared laser aimed at the gold nanorods
while accurately sensing temperature with the nanocrystals. The authors'lab specialises in fabricating bright fluorescent diamond nanocrystals.
The paticularity of these nanocrystals is that they contain a high concentration of punctual colour centre defects.
When exposed to green light, these centres emit a red fluorescent light, useful for sub-cellular imaging applications.
Unlike ordinary fluorescent material, these centres can also be turned into hypersensitive nanoprobes to detect temperature and magnetic field, via optical manipulation and detection.
By introducing gold nanoparticles to the nanocrystal, the authors make it possible to convert the incoming laser light into extremely localised heat.
These gold nanoparticles can therefore act as switchable nanoheaters for therapies based on delivering intense and precise heat to cancerous cells,
using a laser as the energy source. The novelty of this study is that it shows that it is possible to use diamond nanocrystals as hypersensitive temperature sensors with a high spatial resolution-ranging from 10 to 100 nanometers-to monitor the amount of heat delivered to cancer cells s
#Better together: Graphene-nanotube hybrid switches But together, these two materials make a workable digital switch,
which is the basis for controlling electrons in computers, phones, medical equipment and other electronics. Yoke Khin Yap, a professor of physics at Michigan Technological University, has worked with a research team that created these digital switches by combining graphene and boron nitride nanotubes.
The journal Scientific Reports recently published their work.""The question is: How do you fuse these two materials together?"
"Yap says. The key is in maximizing their existing chemical structures and exploiting their mismatched features.
Nanoscale Tweaks Graphene is a molecule-thick sheet of carbon atoms; the nanotubes are made like straws of boron and nitrogen.
Yap and his team exfoliate graphene and modify the material's surface with tiny pinholes.
Then they can grow the nanotubes up and through the pinholes. Meshed together like this, the material looks like a flake of bark sprouting erratic, thin hairs."
"When we put these two aliens together, we create something better, "Yap says, explaining that it's important that the materials have lopsided band gaps,
or differences in how much energy it takes to excite an electron in the material.""When we put them together,
you form a band gap mismatch--that creates a so-called'potential barrier'that stops electrons.""The band gap mismatch results from the materials'structure:
graphene's flat sheet conducts electricity quickly, and the atomic structure in the nanotubes halts electric currents.
This disparity creates a barrier, caused by the difference in electron movement as currents move next to and past the hairlike boron nitride nanotubes.
These points of contact between the materials--called heterojunctions--are what make the digital on/off switch possible."
"Imagine the electrons are like cars driving across a smooth track, "Yap says.""They circle around and around,
but then they come to a staircase and are forced to stop.""Yap and his research team have shown also that
because the materials are respectively so effective at conducting or stopping electricity, the resulting switching ratio is high.
In other words, how fast the materials can turn on and off is several orders of magnitude greater than current graphene switches.
In turn, this speed could eventually quicken the pace of electronics and computing. Solving the Semiconductor Dilemma To get to faster and smaller computers one day,
Yap says this study is a continuation of past research into making transistors without semiconductors.
The problem with semiconductors like silicon is that they can only get so small and they give off a lot of heat;
the use of graphene and nanotubes bypasses those problems. In addition, the graphene and boron nitride nanotubes have the same atomic arrangement pattern,
or lattice matching. With their aligned atoms, the graphene-nanotube digital switches could avoid the issues of electron scattering."
"You want to control the direction of the electrons, "Yap explains, comparing the challenge to a pinball machine that traps,
slows down and redirects electrons.""This is difficult in high speed environments, and the electron scattering reduces the number and speed of electrons."
"Much like an arcade enthusiast, Yap says he and his team will continue trying to find ways to outsmart
or change the pinball setup of graphene to minimize electron scattering. And one day, all their tweaks could make for faster computers--and digital pinball games--for the rest of us s
#Artificial blood vessels become resistant to thrombosis Abstract: Scientists from ITMO University developed artificial blood vessels that are not susceptible to blood clot formation.
The achievement was made possible by a new generation of drug-containing coating applied to the inner surface of the vessel.
The results of the study were published in the Journal of Medicinal Chemistry. Surgery, associated with cardiovascular diseases, such as ischemia,
often require the implantation of vascular grafts-artificial blood vessels, aimed at restoring the blood flow in a problematic part of the circulatory system.
A serious disadvantage of vascular grafts is their tendency to get blocked due to clot formation
which results in compulsory and lifelong intake of anticoagulants among patients and sometimes may even require an additional surgical intervention.
In the study, a research team led by Vladimir Vinogradov, head of the International Laboratory of Solution Chemistry of Advanced Materials and Technologies at ITMO University proposed a solution to the problem.
The team managed to synthesize a thin film made of densely packed aluminum oxide nanorods blended with molecules of a thrombolytic enzyme (urokinase-type plasminogen activator.
Adhered to the inner surface of a vascular graft, the film causes the parietal area of the graft to get filled with a stable concentration of a substance, called plasmin,
which is capable of dissolving the appearing clots. The unique properties of the film arise from its structure,
which represents a porous matrix, accommodating the plasminogen activator. The matrix protects the plasminogen activator from the aggressive environment of the organism,
at the same time preserving the ability of the enzyme to interact with certain external agents through a system of pores.
they actively release medicine into the blood. The lifetime of such grafts is determined often by the amount of drug stored within the graft,
but to any kind of implants. You just need to take the right kind of drug. For example, after the implantation of an artificial ureter, urease crystals often start to grow inside
and doctors do not know how to deal with this problem. It is possible to apply a similar drug-containing coating that dissolves urease.
The same approach may be used for kidney or liver surgery, but these are plans for the future,
"concludes Vladimir Vinogradov v
#Sandcastles inspire new nanoparticle binding technique"Nanocapillary-mediated magnetic assembly of nanoparticles into ultraflexible filaments and reconfigurable networks"Abstract:
The fabrication of multifunctional materials with tunable structure and properties requires programmed binding of their building blocks.
For example, particles organized in long-ranged structures by external fields can be bound permanently into stiff chains through electrostatic or Van der waals attraction,
or into flexible chains through soft molecular linkers such as surface-grafted DNA or polymers. Here, we show that capillarity-mediated binding between magnetic nanoparticles coated with a liquid lipid shell can be used for the assembly of ultraflexible microfilaments and network structures.
These filaments can be regenerated magnetically on mechanical damage, owing to the fluidity of the capillary bridges between nanoparticles and their reversible binding on contact.
Nanocapillary forces offer opportunities for assembling dynamically reconfigurable multifunctional materials that could find applications as micromanipulators, microbots with ultrasoft joints,
Sandcastles inspire new nanoparticle binding technique If you want to form very flexible chains of nanoparticles in liquid
in order to build tiny robots with flexible joints or make magnetically self-healing gels, you need to revert to childhood
researchers from North carolina State university and the University of North carolina-Chapel hill show that magnetic nanoparticles encased in oily liquid shells can bind together in water,
and creates capillary bridges between them so that the particles stick together on contact, "said Orlin Velev, INVISTA Professor of Chemical and Biomolecular engineering at NC State and the corresponding author of the paper."
"We then add a magnetic field to arrange the nanoparticle chains and provide directionality, "said Bhuvnesh Bharti,
research assistant professor of chemical and biomolecular engineering at NC State and first author of the paper.
Chilling the oil is like drying the sandcastle. Reducing the temperature from 45 degrees Celsius to 15 degrees Celsius freezes the oil
and makes the bridges fragile, leading to breaking and fragmentation of the nanoparticle chains. Yet the broken nanoparticles chains will reform
if the temperature is raised, the oil liquefies and an external magnetic field is applied to the particles."
"In other words, this material is temperature responsive, and these soft and flexible structures can be pulled apart
and Engineering Center that facilitates interactions between Triangle universities.""said Michael Rubinstein, John P. Barker Distinguished Professor of Chemistry at UNC and one of the co-authors of the paper r
#Tantalizing discovery may boost memory technology: Rice university scientists make tantalum oxide practical for high-density devices Scientists at Rice university have created a solid-state memory technology that allows for high-density storage with a minimum incidence of computer errors.
The memories are based on tantalum oxide, a common insulator in electronics. Applying voltage to a 250-nanometer-thick sandwich of graphene, tantalum,
nanoporous tantalum oxide and platinum creates addressable bits where the layers meet. Control voltages that shift oxygen ions
and vacancies switch the bits between ones and zeroes. The discovery by the Rice lab of chemist James Tour could allow for crossbar array memories that store up to 162 gigabits
much higher than other oxide-based memory systems under investigation by scientists. Eight bits equal one byte;
a 162-gigabit unit would store about 20 gigabytes of information. Details appear online in the American Chemical Society journal Nano Letters.
Like the Tour lab's previous discovery of silicon oxide memories, the new devices require only two electrodes per circuit,
making them simpler than present-day flash memories that use three.""But this is a new way to make ultradense, nonvolatile computer memory,
"Tour said. Nonvolatile memories hold their data even when the power is off, unlike volatile random-access computer memories that lose their contents
when the machine is shut down. Modern memory chips have many requirements: They have to read and write data at high speed
and hold as much as possible. They must also be durable and show good retention of that data
while using minimal power. Tour said Rice's new design, which requires 100 times less energy than present devices,
has the potential to hit all the marks.""This tantalum memory is based on two-terminal systems,
so it's all set for 3-D memory stacks, "he said.""And it doesn't even need diodes
or selectors, making it one of the easiest ultradense memories to construct. This will be a real competitor for the growing memory demands in high-definition video storage and server arrays."
"The layered structure consists of tantalum, nanoporous tantalum oxide and multilayer graphene between two platinum electrodes.
In making the material, the researchers found the tantalum oxide gradually loses oxygen ions, changing from an oxygen-rich, nanoporous semiconductor at the top to oxygen-poor at the bottom.
Where the oxygen disappears completely, it becomes pure tantalum, a metal. The researchers determined three related factors give the memories their unique switching ability.
First, the control voltage mediates how electrons pass through a boundary that can flip from an ohmic (current flows in both directions) to a Schottky (current flows one way) contact and back.
Second the boundary's location can change based on oxygen vacancies. These are"holes"in atomic arrays where oxygen ions should exist,
Third, the flow of current draws oxygen ions from the tantalum oxide nanopores and stabilizes them.
These negatively charged ions produce an electric field that effectively serves as a diode to hinder error-causing crosstalk.
and a way to control the size of the nanopores. Wang is an assistant professor at the Korea University-Korea Institute of Science and Technology's Graduate school of Converging Science and Technology.
Co-authors are former Rice research scientist Jae-Hwang Lee, an assistant professor of mechanical and industrial engineering at the University of Massachusetts
Amherst; and Rice postdoctoral researchers Yang Yang, Gedeng Ruan, Nam Dong Kim and Yongsung Ji.
Tour is the T. T. and W. F. Chao Chair in Chemistry as well as a professor of materials science and nanoengineering and of computer science and a member of Rice's Richard E. Smalley Institute for Nanoscale Science and Technology y
#New ORNL hybrid microscope offers unparalleled capabilities A microscope being developed at the Department of energy's Oak ridge National Laboratory will allow scientists studying biological and synthetic materials to simultaneously observe chemical and physical properties on and beneath the surface.
The Hybrid Photonic Mode-Synthesizing Atomic Force Microscope is unique, according to principal investigator Ali Passian of ORNL's Quantum Information system group.
As a hybrid, the instrument, described in a paper published in Nature Nanotechnology, combines the disciplines of nanospectroscopy and nanomechanical microscopy."
"It allows researchers to study the surface and subsurface of synthetic and biological samples, which is a capability that until now didn't exist."
"The originality of the instrument and technique lies in its ability to provide information about a material's chemical composition in the broad infrared spectrum of the chemical composition while showing the morphology of a material's interior and exterior with nanoscale-a billionth of a meter-resolution,
Researchers will be able to study samples ranging from engineered nanoparticles and nanostructures to naturally occurring biological polymers, tissues and plant cells.
The first application as part of DOE's Bioenergy Science Center was in the examination of plant cell walls under several treatments to provide submicron characterization.
The plant cell wall is layered a nanostructure of biopolymers such as cellulose. Scientists want to convert such biopolymers to free the useful sugars and release energy An earlier instrument,
also invented at ORNL, provided imaging of poplar cell wall structures that yielded unprecedented topological information, advancing fundamental research in sustainable biofuels.
Because of this new instrument's impressive capabilities, the researcher team envisions broad applications.""An urgent need exists for new platforms that can tackle the challenges of subsurface and chemical characterization at the nanometer scale,
"said co-author Rubye Farahi.""Hybrid approaches such as ours bring together multiple capabilities, in this case, spectroscopy and high-resolution microscopy."
chemical or biological processes at the nanoscale To gain even deeper insights into the smallest of worlds,
Computer-assisted technology developed especially for this purpose combines the advantages of both methods and suppresses unwanted noise.
This makes highly precise filming of dynamic processes at the nanometer scale possible. The results were published recently in the research journal Scientific Reports.
Many important but complex processes in the natural and life sciences, for example, photosynthesis or high-temperature superconductivity, have yet to be understood.
On the one hand, this is due to the fact that such processes take place on a scale of a millionth of a millimeter (nanometer)
It enables unaltered optical measurements of extremely small, dynamic changes in biological, chemical or physical processes.
"This makes our nanoscope suitable for viewing ultra-fast physical processes as well as for biological process, which are often very slow,
Combining two methods guarantees high spatial and temporal Resolution The nanoscope is based on the further development of near-field microscopy, in
"The focused light delivers energy to the sample, creating a special interaction between the point and the sample in
one can achieve a spatial resolution in the order of the near-field magnitude, that is, in the nanometer range."
pressure or electric field pulses is as follows: while a first pulse excites the sample under study, a second pulse monitors the change in the sample.
If the time between them is varied, snapshots can be taken at different times, and a movie can be assembled.
the teams led by the two Dresden physicists have managed to combine all the advantages of both methods in their nanoscope."
"We have developed software with a special demodulation technology with which--in addition to the outstanding resolution of near-field optical microscopy that is at least three orders of magnitude better than the resolution of common ultra-fast spectroscopy--we can now also measure dynamic changes in the sample with high sensitivity,
The clever electronic method enables the nanoscope to exclusively record only the changes actually occurring in the sample's properties due to the excitation.
Although other research groups have reported only recently good temporal resolution with their nanoscopes, they could not, however,
Universal in every respect"With our nanoscope's considerable wavelength coverage, dynamic processes can be studied with the best suited wavelengths for the specific process under study.
The Dresden nanoscope is universally adaptable to respective scientific questions. The probe pulse wavelengths can,
The sample can be stimulated with laser, pressure, electric field or magnetic field pulses. The principle was tested at the HZDR on a typical laboratory laser as well as on the free-electron laser FELBE.
and magnetic field pulses for excitation, are in preparation.""In the future, we will not only see how quickly a process occurs,
a team led by scientists from the RIKEN Center for Emergent Matter Science in Japan has developed a new hydrogel that works like an artificial muscle--quickly stretching
They have managed also to use the polymer to build an L-shaped object that slowly walks forward as the temperature is raised repeatedly and lowered.
Hydrogels are polymers that can maintain large quantities of water within their networks. Because of this, they can swell
and shrink in response to changes in the environment such as voltage, heat, and acidity. In this sense they are actually similar to the plant cells,
the team arranged metal-oxide nanosheets into a single plane within a material by using a magnetic field
and then fixed them in place using a procedure called light-triggered in-situ vinyl polymerization, which essentially uses light to congeal a substance into a hydrogel.
The nanosheets ended up stuck within the polymer, aligned in a single plane. Due to electrostatic forces, the sheets create electrostatic resistance in one direction but not in the other.
which we calculated to be 32 degrees Celsius, the polymer rapidly changed shape, stretching in length.
and in a liquid environment, showing that it doesn't require the uptake of water.
So in other words, it will work even in a normal air environment.""The team members were intrigued to find, additionally,
As a demonstration of how the polymer could be put to practical use, the group designed an L-shaped piece of polymer that can actually walk, in a water environment,
as the legs lengthen and contract in response to changing temperature. The group now plans to conduct further studies to create substances that can be used in practical applications.
#Discovery in growing graphene nanoribbons could enable faster, more efficient electronics Abstract: Graphene, an atom-thick material with extraordinary properties, is a promising candidate for the next generation of dramatically faster, more energy-efficient electronics.
However, scientists have struggled to fabricate the material into ultra-narrow strips, called nanoribbons, that could enable the use of graphene in high-performance semiconductor electronics.
Now, University of Wisconsin-Madison engineers have discovered a way to grow graphene nanoribbons with desirable semiconducting properties directly on a conventional germanium semiconductor wafer.
This advance could allow manufacturers to easily use graphene nanoribbons in hybrid integrated circuits, which promise to significantly boost the performance of next-generation electronic devices.
The technology could also have specific uses in industrial and military applications such as sensors that detect specific chemical and biological species
and photonic devices that manipulate light. In a paper published Aug 10 in the journal Nature Communications, Michael Arnold, an associate professor of materials science and engineering at UW-Madison, Ph d. student Robert Jacobberger,
and their collaborators describe their new approach to producing graphene nanoribbons. Importantly, their technique can easily be scaled for mass production
and is compatible with the prevailing infrastructure used in semiconductor processing.""Graphene nanoribbons that can be grown directly on the surface of a semiconductor like germanium are more compatible with planar processing that's used in the semiconductor industry,
and so there would be less of a barrier to integrating these really excellent materials into electronics in the future,
"Arnold says. Graphene, a sheet of carbon atoms that is only one atom in thickness, conducts electricity and dissipates heat much more efficiently than silicon,
the material most commonly found in today's computer chips. But to exploit graphene's remarkable electronic properties in semiconductor applications where current must be switched on and off
graphene nanoribbons need to be less than 10 nanometers wide, which is phenomenally narrow. In addition, the nanoribbons must have smooth,
well-defined"armchair"edges in which the carbon-carbon bonds are parallel to the length of the ribbon.
Researchers have fabricated typically nanoribbons by using lithographic techniques to cut larger sheets of graphene into ribbons.
However, this"top-down"fabrication approach lacks precision and produces nanoribbons with very rough edges. Another strategy for making nanoribbons is to use a"bottom-up"approach such as surface-assisted organic synthesis,
where molecular precursors react on a surface to polymerize nanoribbons. Arnold says surface-assisted synthesis can produce beautiful nanoribbons with precise
smooth edges, but this method only works on metal substrates and the resulting nanoribbons are thus far too short for use in electronics.
To overcome these hurdles, the UW-Madison researchers pioneered a bottom-up technique in which they grow ultra-narrow nanoribbons with smooth,
straight edges directly on germanium wafers using a process called chemical vapor deposition. In this process, the researchers start with methane,
which adsorbs to the germanium surface and decomposes to form various hydrocarbons. These hydrocarbons react with each other on the surface,
where they form graphene. Arnold's team made its discovery when it explored dramatically slowing the growth rate of the graphene crystals by decreasing the amount of methane in the chemical vapor deposition chamber.
They found that at a very slow growth rate, the graphene crystals naturally grow into long nanoribbons on a specific crystal facet of germanium.
By simply controlling the growth rate and growth time, the researchers can easily tune the nanoribbon width be to less than 10 nanometers."
"What we've discovered is that when graphene grows on germanium, it naturally forms nanoribbons with these very smooth, armchair edges,
"Arnold says.""The widths can be very, very narrow and the lengths of the ribbons can be very long,
so all the desirable features we want in graphene nanoribbons are happening automatically with this technique.""The nanoribbons produced with this technique start nucleating,
or growing, at seemingly random spots on the germanium and are oriented in two different directions on the surface.
Arnold says the team's future work will include controlling where the ribbons start growing
and aligning them all in the same direction. The researchers are patenting their technology through the Wisconsin Alumni Research Foundation.
The research was supported primarily by the Department of energy's Basic energy Sciences program m
#Flexible, biodegradable device can generate power from touch (video) Longstanding concerns about portable electronics include the devices'short battery life and their contribution to e waste.
One group of scientists is now working on a way to address both of these seeming unrelated issues at the same time.
They report in the journal ACS Applied materials & Interfaces the development of a biodegradable nanogenerator made with DNA that can harvest the energy from everyday motion and turn it into electrical power.
Many people may not realize it, but the movements we often take for granted such as walking and tapping on our keyboards release energy that largely dissipates,
unused. Several years ago, scientists figured out how to capture some of that energy and convert it into electricity so we might one day use it to power our mobile gadgetry.
Achieving this would not only untether us from wall outlets, but it would also reduce our demand on fossil-fuel-based power sources.
The first prototypes of these nanogenerators are currently being developed in laboratories around the world. And now, one group of scientists wants to add another feature to this technology:
biodegradability. The researchers built a nanogenerator using a flexible, biocompatible polymer film made out of polyvinylidene fluoride, or PVDF.
To improve the material's energy harvesting ability, they added DNA, which has good electrical properties
and is biocompatible and biodegradable. Their device was powered with gentle tapping, and it lit up 22 to 55 light-emitting diodes.
The authors acknowledge funding from the Science and Engineering Research Board of India I
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