Saturday, April 11, 2015

Plaque-busting nanoparticles could help fight tooth decay

Nanoparticles carry the antibacterial drug farnesol to the surface of the teeth, where they release their payload when triggered by acidic environments.

Nanotechnology might soon save you a trip to the dentist. Researchers have developed tiny sphere-shaped particles that ferry a payload of bacteria-slaying drugs to the surface of the teeth, where they fight plaque and tooth decay on the spot. The approach could also be adapted to combat other plaquelike substances, known as biofilms, such as those that form on medical devices like orthopedic implants.
"It's quite clever," says oral microbiologist Robert Allaker of Queen Mary University of London, who was not involved with the research. "I think it was an innovative piece of work."
Plaque is a film made up of bacteria and a matrix of polymers composed of linked sugars, which clings tenaciously to teeth. When bacteria digest sugars in the mouth, they produce acid as a byproduct, which eats away at teeth, eventually causing decay. Topical antibacterial drugs don’t work well on plaque because saliva quickly washes them away.

Nanoparticles can solve this problem by clinging to the surface of teeth and carrying drugs along with them. Although this is not the first technique to employ such a strategy, the research improves upon previous methods, because these particles attach not only to the tooth, but also to the plaque biofilm.

Friday, April 10, 2015

Engineers now understand how complex carbon nanostructures form

CNTs are much smaller than the width of a human hair and naturally form "forests" when they are created in large numbers. These forests, held together by a nanoscale adhesive force known as the van der Waals force, are categorized based on their rigidity or how they are aligned. For example, if CNTs are dense and well aligned, the material tends to be more rigid and can be useful for electrical and mechanical applications. If CNTs are disorganized, they tend to be softer and have entirely different sets of properties.

"Scientists are still learning how carbon nanotube arrays form," said Matt Maschmann, assistant professor of mechanical and aerospace engineering in the College of Engineering at MU. "As they grow in relatively dense populations, mechanical forces combine them into vertically oriented assemblies known as forests or arrays. The complex structures they form help dictate the properties the CNT forests possess. We're working to identify the mechanisms behind how those forests form, how to control their formation and thus dictate future uses for CNTs."
Currently, most models that examine CNT forests analyze what happens when you compress them or test their thermal or conductivity properties after they've formed. However, these models do not take into account the process by which that particular forest was created and struggle to capture realistic CNT forest structure.


Monday, March 30, 2015

Carbon nanotube fibers make superior links to brain






Carbon nanotube fibers invented at Rice University may provide the best way to communicate directly with the brain.
The fibers have proven superior to metal electrodes for deep brain stimulation and to read signals from a neuronal network. Because they provide a two-way connection, they show promise for treating patients with neurological disorders while monitoring the real-time response of neural circuits in areas that control movement, mood and bodily functions.
New experiments at Rice demonstrated the biocompatible fibers are ideal candidates for small, safe electrodes that interact with the brain's neuronal system, according to the researchers. They could replace much larger electrodes currently used in devices for deep brain stimulation therapies in Parkinson's disease patients.
They may also advance technologies to restore sensory or motor functions and brain-machine interfaces as well as deep brain stimulation therapies for other neurological disorders, including dystonia and depression, the researchers wrote.
The paper appeared online this week in the American Chemical Society journal ACS Nano.
The fibers created by the Rice lab of chemist and chemical engineer Matteo Pasquali consist of bundles of long nanotubes originally intended for aerospace applications where strength, weight and conductivity are paramount.
The individual nanotubes measure only a few nanometers across, but when millions are bundled in a process called wet spinning, they become thread-like fibers about a quarter the width of a human hair.
"We developed these fibers as high-strength, high-conductivity materials," Pasquali said. "Yet, once we had them in our hand, we realized that they had an unexpected property: They are really soft, much like a thread of silk. Their unique combination of strength, conductivity and softness makes them ideal for interfacing with the electrical function of the human body."

Friday, March 27, 2015

Nanofibers twisted together to create structures tougher than bullet proof vests -- ScienceDaily

Researchers at the University of Texas at Dallas have created new structures that exploit the electromechanical properties of specific nanofibers to stretch to up to seven times their length, while remaining tougher than Kevlar.

Saturday, February 14, 2015

Biomedical use of gold nanotubes demonstrated in mouse model of human cancer

Scientists have shown that gold nanotubes have many applications in fighting cancer: internal nanoprobes for high-resolution imaging; drug delivery vehicles; and agents for destroying cancer cells.

The study, published today in the journal Advanced Functional Materials, details the first successful demonstration of the biomedical use of gold nanotubes in a mouse model of human cancer.

Study lead author Dr Sunjie Ye, who is based in both the School of Physics and Astronomy and the Leeds Institute for Biomedical and Clinical Sciences at the University of Leeds, said: "High recurrence rates of tumours after surgical removal remain a formidable challenge in cancer therapy. Chemo- or radiotherapy is often given following surgery to prevent this, but these treatments cause serious side effects.

Gold nanotubes - that is, gold nanoparticles with tubular structures that resemble tiny drinking straws - have the potential to enhance the efficacy of these conventional treatments by integrating diagnosis and therapy in one single system."

The researchers say that a new technique to control the length of nanotubes underpins the research. By controlling the length, the researchers were able to produce gold nanotubes with the right dimensions to absorb a type of light called 'near infrared'.

Saturday, February 7, 2015

Why 'baking powder' doubles or triples efficiency of plastic solar cells

Why 'baking powder' doubles or triples efficiency of plastic solar cells 

Nano-hydrogels that attack cancer cells

Hydrogels are materials that are commonly used in everyday objects such as contact lenses or diapers, in order to control humidity. However, chemical engineers at the University of Guadalajara (UdeG), in Mexico, developed a new technology based on thermosensitive nanoparticles (nano-hydrogels) to use these materials in the field of biomedicine, as an alternative to achieve controlled release of anticancer drugs.

Friday, January 23, 2015

Gold 'nano-drills' help with DNA analysis

Researcher Lennart de Vreede applied a large number of microscopic discs of gold on a surface of silicon dioxide. When heated up for several hours, the gold is moving into the material, perpendicular to the surface, like nanometer-sized spheres. Nine hours of heating gives a tunnel of 800 nanometers in length, for example, and a diameter of 25 nanometer: these results can normally only be acieved by using complex processes. The gold can even fully move through the material. All nanotunnels together then form a sieve. Leaving the tunnel closed at one end, leaves open the possibility of creating molds for nano structures.
Once heating to close to their melting point, the gold discs -- diameter one micron -, don't spread out over the surface, but they form spheres. They push away the siliciumdioxide, causing a circular 'ridge', a tiny dam. While moving into the silicondioxide, the ball gets smaller: it evaporates and there is a continuos movement of silicondioxide.
For example in DNA-sequencing applications, De Vreede sees applications for this new fabrication technology. In that case, a DNA-string is pulled through one of these nano-channels, after which the building blocks of DNA, the nucleotides, can be analysed subsequently. Furthermore, De Vreede expects the 'gold method' to be applicable to other ceramic materials as well. His recent experiments on silicium nitride indicate that.




Gold 'nano-drills' help with DNA analysis 

Tuesday, January 20, 2015

NC State researchers develop wearable nanowire sensor to monitor electrophysiological signals

Researchers from North Carolina State University have developed a new, wearable sensor that uses silver nanowires to monitor electrophysiological signals, such as electrocardiography (EKG) or electromyography (EMG). The new sensor is as accurate as the "wet electrode" sensors used in hospitals, but can be used for long-term monitoring and is more accurate than existing sensors when a patient is moving.

Long-term monitoring of electrophysiological signals can be used to track patient health or assist in medical research, and may also be used in the development of new powered prosthetics that respond to a patient's muscular signals.

Electrophysiological sensors used in hospitals, such as EKGs, use wet electrodes that rely on an electrolytic gel between the sensor and the patient's skin to improve the sensor's ability to pick up the body's electrical signals. However, this technology poses problems for long-term monitoring, because the gel dries up - irritating the patient's skin and making the sensor less accurate.

The new nanowire sensor is comparable to the wet sensors in terms of signal quality, but is a "dry" electrode - it doesn't use a gel layer, so doesn't pose the same problems that wet sensors do.

Friday, January 16, 2015

"Extra-short nanowires best for brain"

If in the future electrodes are inserted into the human brain - either for research purposes or to treat diseases - it may be appropriate to give them a 'coat' of nanowires that could make them less irritating for the brain tissue. However, the nanowires must not exceed a certain length, according to new research from Neuronano Research Center at Lund University in Sweden.


Monday, January 12, 2015

'Glowing' new nanotechnology guides cancer surgery, also kills remaining malignant cells..

Researchers at Oregon State University have developed a new way to selectively insert compounds into cancer cells -- a system that will help surgeons identify malignant tissues and then, in combination with phototherapy, kill any remaining cancer cells after a tumor is removed.

It's about as simple as, "If it glows, cut it out." And if a few malignant cells remain, they'll soon die.

The findings, published in the journal Nanoscale, have shown remarkable success in laboratory animals. The concept should allow more accurate surgical removal of solid tumors at the same time it eradicates any remaining cancer cells. In laboratory tests, it completely prevented cancer recurrence after phototherapy.

Technology such as this, scientists said, may have a promising future in the identification and surgical removal of malignant tumors, as well as using near-infrared light therapies that can kill remaining cancer cells, both by mild heating of them and generating reactive oxygen species that can also kill them.

"This is kind of a double attack that could significantly improve the success of cancer surgeries," said Oleh Taratula, an assistant professor in the OSU College of Pharmacy.

"With this approach, cancerous cells and tumors will literally glow and fluoresce when exposed to near-infrared light, giving the surgeon a precise guide about what to remove," Taratula said. "That same light will activate compounds in the cancer cells that will kill any malignant cells that remain. It's an exciting new approach to help surgery succeed."

Friday, January 9, 2015

Germanium: Semiconductor milestone

A laboratory at Purdue University provided a critical part of the world's first transistor in 1947 -- the purified germanium semiconductor -- and now researchers there are on the forefront of a new germanium milestone. The team has created the first modern germanium circuit -- a complementary metal-oxide-semiconductor (CMOS) device -- using germanium as the semiconductor instead of silicon.
The team has created the first modern germanium circuit -- a complementary metal-oxide-semiconductor (CMOS) device -- using germanium as the semiconductor instead of silicon.
"Bell Labs created the first transistor, but the semiconductor crystal made of purified germanium was provided by Purdue physicists," said Peide "Peter" Ye, a Purdue professor of electrical and computer engineering.

Germanium was superseded by silicon as the semiconductor of choice for commercial CMOS technology. However, the industry will soon reach the limit as to how small silicon transistors can be made, threatening future advances. Germanium is one material being considered to replace silicon because it could enable the industry to make smaller transistors and more compact integrated circuits, Ye said.
Compared to silicon, germanium also is said to have a "higher mobility" for electrons and electron "holes," a trait that makes for ultra-fast circuits.

In new findings, Purdue researchers show how to use germanium to produce two types of transistors needed for CMOS electronic devices. The material had previously been limited to "P-type" transistors. The findings show how to use the material also to make "N-type" transistors. Because both types of transistors are needed for CMOS circuits, the findings point to possible applications for germanium in computers and electronics, he said.
Findings will be detailed in two papers being presented during the 2014 IEEE International Electron Devices Meeting on Dec. 15-17 in San Francisco. One paper was authored by Ye and graduate students Heng Wu, Nathan Conrad and Wei Luo, the same authors of the second paper together with graduate students Mengwei Si, Jingyun Zhang and Hong Zhou.




Germanium: Semiconductor milestone

Thursday, January 8, 2015

Nanotechnology against malaria parasites



















For many infectious diseases no vaccine currently exists. In addition, resistance against currently used drugs is spreading rapidly. To fight these diseases, innovative strategies using new mechanisms of action are needed. The malaria parasite Plasmodium falciparum that is transmitted by the Anophelesmosquito is such an example. Malaria is still responsible for more than 600,000 deaths annually, especially affecting children in Africa (WHO, 2012).

Malaria parasites invade human red blood cells, they then disrupt them and infect others. Researchers at the University of Basel and the Swiss Tropical and Public Health Institute have now developed so-called nanomimics of host cell membranes that trick the parasites. This could lead to novel treatment and vaccination strategies in the fight against malaria and other infectious diseases. Their research results have been published in the scientific journal ACS Nano.

Artificial bubbles with receptors
Malaria parasites normally invade human red blood cells in which they hide and reproduce. They then make the host cell burst and infect new cells. Using nanomimics, this cycle can now be effectively disrupted: The egressing parasites now bind to the nanomimics instead of the red blood cells.
Researchers of groups led by Prof. Wolfgang Meier, Prof. Cornelia Palivan (both at the University of Basel) and Prof. Hans-Peter Beck (Swiss TPH) have successfully designed and tested host cell nanomimics. For this, they developed a simple procedure to produce polymer vesicles -- small artificial bubbles -- with host cell receptors on the surface. The preparation of such polymer vesicles with water-soluble host receptors was done by using a mixture of two different block copolymers. In aqueous solution, the nanomimics spontaneously form by self-assembly.
Blocking parasites efficiently
Usually, the malaria parasites destroy their host cells after 48 hours and then infect new red blood cells. At this stage, they have to bind specific host cell receptors. Nanomimics are now able to bind the egressing parasites, thus blocking the invasion of new cells. The parasites are no longer able to invade host cells, however, they are fully accessible to the immune system.
The researchers examined the interaction of nanomimics with malaria parasites in detail by using fluorescence and electron microscopy. A large number of nanomimics were able to bind to the parasites and the reduction of infection through the nanomimics was 100-fold higher when compared to a soluble form of the host cell receptors. In other words: In order to block all parasites, a 100 times higher concentration of soluble host cell receptors is needed, than when the receptors are presented on the surface of nanomimics.
"Our results could lead to new alternative treatment and vaccines strategies in the future," says Adrian Najer first-author of the study. Since many other pathogens use the same host cell receptor for invasion, the nanomimics might also be used against other infectious diseases. The research project was funded by the Swiss National Science Foundation and the NCCR "Molecular Systems Engineering."


Wednesday, January 7, 2015

Nanoscale resistors for quantum devices





The electrical characteristics of new thin-film chromium oxide resistors that can be tuned by controlling the oxygen content detailed in theJournal of Applied Physics. Researchers from the London Centre for Nanotechnology have made new compact, high-value resistors for nanoscale quantum circuits. The resistors could speed the development of quantum devices for computing and fundamental physics research. The researchers describe the thin-film resistors in an article in the Journal of Applied Physics, from AIP Publishing.


One example of an application that requires high-value resistors is the quantum phase-slip (QPS) circuit. A QPS circuit is made from very narrow wires of superconducting material that can exploit a fundamental, counterintuitive quantum mechanical property called quantum tunneling to move magnetic flux to and fro across the wire, over energy barriers that would be insurmountable in the everyday world of classical physics.
In 2006, scientists from the Kavli Institute of Nanoscience in the Netherlands proposed that a QPS circuit could be used to redefine the amp -- a standard unit of measure for electrical current -- by linking it to fundamental properties of the universe (as opposed to a physical system kept in a standards lab). Other scientific groups have also proposed using QPS devices as qubits in quantum computers -- the fundamental unit of quantum information at the heart of such computers.
Resistors are needed to isolate the fragile quantum states in QPS devices from the noisy classical world, said Paul Warburton, an experimentalist at the London Centre for Nanotechnology who studies the electronic properties of nanoscale devices. "In the application as a current standard, the resistors also enable the device to operate stably," he added.
Yet standard materials used to make resistors for integrated circuits do not typically provide enough resistance in a small enough form to meet the requirements for QPS circuits.
Warburton and his colleagues turned to the compound chromium oxide to create new high-value, compact nanoscale resistors. The researchers created thin films of chromium oxide using a technique called sputter deposition. They were able to tune the resistance of the chromium oxide films by controlling the oxygen content of the films: the higher the oxygen content, the higher the resistance.
"Replacing chromium with oxygen affects both the numbers of electrons available to carry current and also the availability of paths for electrons to hop through the material," explained Warburton.






Monday, January 5, 2015

New technique allows low-cost creation of 3-D nano structures



  








Researchers from North Carolina State University have   developed a new lithography technique that uses nanoscale spheres to create three-dimensional (3-D) structures with biomedical, electronic and photonic applications. The new technique is significantly less expensive than conventional methods and does not rely on stacking two-dimensional (2-D) patterns to create 3-D structures.

"Our approach reduces the cost of nanolithography to the point where it could be done in your garage," says Dr. Chih-Hao Chang, an assistant professor of mechanical and aerospace engineering at NC State and senior author of a paper on the work.
Most conventional lithography uses a variety of techniques to focus light on a photosensitive film to create 2-D patterns. These techniques rely on specialized lenses, electron beams or lasers -- all of which are extremely expensive. Other conventional techniques use mechanical probes, which are also costly. To create 3-D structures, the 2-D patterns are essentially printed on top of each other.
The NC State researchers took a different approach, placing nanoscale polystyrene spheres on the surface of the photosensitive film.
The nanospheres are transparent, but bend and scatter the light that passes through them in predictable ways according to the angle that the light takes when it hits the nanosphere. The researchers control the nanolithography by altering the size of the nanosphere, the duration of light exposures, and the angle, wavelength and polarization of light. The researchers can also use one beam of light, or multiple beams of light, allowing them to create a wide variety of nanostructure designs.