A team of international scientists has achieved a breakthrough in nanosensing that could have major potential in medical applications.
Researchers have made a breakthrough discovery in identifying the world's most sensitive nanoparticle and measuring it from a distance using light. These super-bright, photostable and background-free nanocrystals enable a new approach to highly advanced sensing technologies, using optical fibres.
This discovery, by a team of researchers from Macquarie University, the University of Adelaide, and Peking University, opens the way for rapid localisation and measurement of cells within a living environment at the nanoscale – such as the changes to a single living cell in the human body in response to chemical signals.
Published yesterday in Nature Nanotechnology, the research outlines a new approach to advanced sensing that combines a specific form of nanocrystal – or "SuperDot" – with a special kind of optical fibre that enables light to interact with tiny (nanoscale) volumes of liquid.
"Until now, measuring a single nanoparticle would have required placing it inside a very bulky and expensive microscope," says Professor Tanya Monro, Director of the University of Adelaide's Institute for Photonics and Advanced Sensing (IPAS). "For the first time, we have been able to detect a single nanoparticle at one end of an optical fibre from the other end. That opens up all sorts of possibilities in sensing."
"Using optical fibres we can reach many new places – such as inside the living human brain, next to a developing embryo, or within an artery – locations that are inaccessible to conventional measurement tools. This ultimately paves the way to breakthroughs in medical treatment. For example, measuring a cell's reaction in real time to a cancer drug means doctors could tell at the time treatment is being delivered whether or not a person is responding to the therapy."
The performance of sensing at single molecular level had previously been limited by both insufficient signal strength and interference from background noise. The special optical fibre engineered at IPAS also proved useful in understanding the properties of nanoparticles: "Material scientists have faced a huge challenge in increasing the brightness of nanocrystals," says Dr. Jin, ARC Fellow at Macquarie University's Advanced Cytometry Laboratories. "Using these optical fibres, however, we have been given unprecedented insight into the light emissions. Now, thousands of emitters can be incorporated into a single SuperDot – creating a far brighter, and more easily detectable nanocrystal."
Under infrared illumination, these SuperDots can selectively produce bright blue, red and infrared light, with a staggering 1,000 times more sensitivity than existing materials. "Neither the glass of the optical fibre nor other background biological molecules respond to infrared, so that removed the background signal issue. By exciting these SuperDots, we were able to lower the detection limit to the ultimate level – a single nanoparticle."
"The trans-disciplinary research from multiple institutions has paved the way for this innovative discovery," Jin continued. "These joint efforts will ultimately benefit patients around the world – for example, our industry partners are developing uses for SuperDots in cancer diagnostic kits, detecting incredibly low numbers of biomarkers."
Researchers at the University of St Andrews have produced the world's fastest spinning man-made object – briefly achieving 600 million revolutions per minute.
The team was able to levitate and then spin a microscopic sphere, purely using laser light in a vacuum. This reached over 600 million RPM before it was lost from the levitation trap. This is 500,000 times faster than a domestic washing machine and more than 1,000 times faster than a dental drill.
Although there is much international research exploring what happens at the boundary between classical physics and quantum physics, most of this experimental work uses atoms or molecules. The St Andrews team aimed to understand what happens for larger objects, containing a trillion atoms or more.
To do this, they manufactured a sphere of calcium carbonate around 4 micrometres in diameter – roughly the width of a typical cell nucleus. They then used miniscule forces of laser light to hold the sphere with the radiation pressure of light, rather like levitating a beach ball with a jet of water.
They exploited the polarisation property of the laser light that changed as the light passed through the levitating sphere, exerting a small twist or torque. Placing the sphere in vacuum largely removed the drag (friction) of any gas environment, allowing the team to achieve the very high rotation rates.
As well as rotation, the team observed a “compression” of the excursions or “wobble” of the particle in three dimensions, which can be understood as a “cooling” of motion. Essentially, the sphere behaved like the world’s smallest gyroscope – stabilising its motion around the axis of rotation.
Dr Yoshihiko Arita of the university's School of Physics and Astronomy: “This is an exciting, thought-provoking experiment that pushes the boundary of our understanding of rotating bodies. I am intrigued with the prospect of extending this to multiple trapped particles and rotating systems. We might even be able to shed light on the area of quantum friction – that is – does quantum mechanics put the brakes on the motion or spinning particle, even with a near-perfect vacuum, with no other apparent sources of friction?”
Dr Michael Mazilu: “This system poses fascinating questions with regard to thermodynamics and is a challenging system to model theoretically. The rotation rate is so fast that the angular acceleration at the sphere surface is 1 billion times that of gravity on the Earth surface – it’s amazing that the centrifugal forces do not cause the sphere to disintegrate.”
Professor Kishan Dholakia: “The team has performed a real breakthrough piece of work that we believe will resonate with the international community. In addition to the exciting fundamental physics aspects, this experiment will allow us to probe the nature of friction in very small systems, which has relevance to the next generation of microscopic devices. And it’s always good to hold a “world record” - even if for only a while!”
A new chemical element with atomic number 115 has been discovered by researchers in Sweden.
Remember the periodic table from chemistry class in school? Researchers from Lund University in Sweden have presented fresh evidence that confirms the existence of a previously unknown chemical element. This new, super-heavy element with atomic number 115 has yet to be named. Experiments were conducted at the GSI research facility in Germany and the results confirm earlier measurements performed by research groups in Russia.
“This was a very successful experiment and is one of the most important in the field in recent years”, said Dirk Rudolph, Professor at the Division of Nuclear Physics at Lund University.
Besides the observations of the new chemical element, the researchers have also gained access to data that gives them a deeper insight into the structure and properties of super-heavy atomic nuclei. By bombarding a thin film of americium with calcium ions, the team was able to measure photons in connection with the new element’s alpha decay. Certain energies of the photons agreed with the expected energies for X-ray radiation, which is a ‘fingerprint’ of a given element.
A committee comprising members of the international unions of pure and applied physics and chemistry will review the findings to decide whether to recommend further experiments before the discovery is officially acknowledged. The study is presented today in the scientific journal ThePhysical Review Letters.
Scientists have developed a new way to detect threatening nanoparticles in food.
Over the last few years, the use of nanomaterials for water treatment, food packaging, pesticides, cosmetics and other industries has increased. For example, farmers have used silver nanoparticles as a pesticide because of their capability to suppress the growth of harmful organisms. However, a growing concern is that these particles could pose a potential health risk to humans and the environment. In a new study, researchers at the University of Missouri have developed a reliable method for detecting silver nanoparticles in fresh produce and other food products.
“More than 1,000 products on the market are nanotechnology-based products,” said Mengshi Lin, associate professor of food science in the MU College of Agriculture, Food and Natural Resources. “This is a concern because we do not know the toxicity of the nanoparticles. Our goal is to detect, identify and quantify these nanoparticles in food and food products and study their toxicity as soon as possible.”
Lin and his colleagues, including MU scientists Azlin Mustapha and Bongkosh Vardhanabhuti, studied the residue and penetration of silver nanoparticles on pear skin. First, the scientists immersed the pears in a silver nanoparticle solution similar to pesticide application. The pears were then washed and rinsed repeatedly. Results showed that four days after the treatment and rinsing, silver nanoparticles were still attached to the skin, and the smaller particles were able to penetrate the skin and reach the pear pulp.
“The penetration of silver nanoparticles is dangerous to consumers, because they have the ability to relocate in the human body after digestion,” Lin said. “Therefore, smaller nanoparticles may be more harmful to consumers than larger counterparts.”
When ingested, nanoparticles pass into the blood and lymph system, circulate through the body and reach potentially sensitive sites such as the spleen, brain, liver and heart.
The growing trend to use other types of nanoparticles has revolutionised the food industry by enhancing flavours, improving supplement delivery, keeping food fresh longer and brightening the colours of food. However, researchers worry that the use of silver nanoparticles could harm the human body.
“This study provides a promising approach for detecting the contamination of silver nanoparticles in food crops or other agricultural products,” Lin said.
Members of Lin’s research team also included Zhong Zang, a food science graduate student. The study was published in the Journal of Agricultural and Food Chemistry.
Researchers at North Carolina State University have created a new flexible nano-scaffold for rechargeable lithium ion batteries that could help make cell phone and electric car batteries last longer.
The research, published in Advanced Materials, shows the potential of manufactured sheets of aligned carbon nanotubes coated with silicon, a material with a much higher energy storage capacity than the graphite composites typically used in lithium ion batteries.
"Putting silicon into batteries can produce a huge increase in capacity – 10 times greater," said Dr. Philip Bradford, assistant professor. "But adding silicon can also create 10 times the problems."
One significant challenge in using silicon is that it swells as lithium ion batteries discharge. As the batteries cycle, silicon can break off from the electrode and float around (known as pulverisation) instead of staying in place, making batteries less stable. When the silicon-coated carbon nanotubes were aligned in one direction – like a layer of drinking straws laid end to end – the structure allowed for controlled expansion, so that the silicon was less prone to pulverisation.
"There's a huge demand for batteries for cell phones and electric vehicles, which need higher energy capacity for longer driving distances between charges," said Xiangwu Zhang, associate professor of textile engineering, chemistry and science at NC State. "We believe this carbon nanotube scaffolding potentially has the ability to change the industry, although technical aspects will have to be worked out. The manufacturing process we're using is scalable and could work well in commercial production."
A novel material with record-breaking surface area and water adsorption abilities has been synthesised by researchers from Uppsala University, Sweden.
Electron microscopy images of Upsalite. Credit: Forsgren J, Frykstrand S, Grandfield K, Mihranyan A, Strømme M (2013)
The new material – based on magnesium carbonate – has been given the name "Upsalite". It is filled with empty pores all less than 10 nanometres in size. This provides a total surface area of more than 800 square metres per gram: the largest ever achieved for an alkali earth metal carbonate. As a result, Upsalite will earn a place in the exclusive class of porous, high surface area materials which includes carbon nanotubes, metal organic frameworks, mesoporous silica and zeolites.
The unique pore structure, seen in the photo above, enables it to absorb more water at low relative humidities than the best materials presently available. It could reduce the amount of energy needed for moisture control and filtering in the electronics and drug formulation industries, for example, as well as in warehouse environments. It could also be used in the collection of toxic waste, chemical/oil spills, odour control and sanitation after fire, cosmetics, ink jet paper and a new generation of biomaterials. Furthermore, it has a very low manufacturing cost.
"In contrast to what has been claimed for more than 100 years in scientific literature, we have found that amorphous magnesium carbonate can be made in a very simple, low-temperature process," says Johan Goméz de la Torre, researcher at the Nanotechnology and Functional Materials Division.
"One Thursday afternoon, we slightly changed the synthesis parameters of the earlier employed unsuccessful attempts, and by mistake left the material in the reaction chamber over the weekend. Back at work on Monday morning we discovered that a rigid gel had formed and after drying this gel we started to get excited."
A year of detailed materials analysis and fine tuning of the experiment followed. One of the researchers got to take advantage of his Russian skill, since some of the chemistry details necessary for understanding the reaction mechanism were only available in an old Russian PhD thesis.
"Having gone through a number of state-of-the-art materials characterisation techniques, it became clear that we had indeed synthesised the material that previously had been claimed impossible to make," says Prof. Maria Strømme, Head of the Nanotechnology and Functional Materials Division.
The discovery was published this week in PLOS ONE. It will be commercialised through the University spin-out company Disruptive Materials, formed by the researchers together with the holding company of Uppsala University.
Researchers at the University of Basel have developed artificial organelles – specialised subunits within a cell – that can support the reduction of toxic oxygen compounds. This could lead to novel drugs that influence pathological states directly inside living cells.
Free radicals are dangerous molecules which can disrupt normal cellular processes. They are produced within the body through various ways – as metabolic byproducts, or through environmental influences such as UV-rays and smog. If the concentration of free radicals in an organism reaches the point where the antioxidant defense mechanism is overwhelmed, the result can be oxidative stress, which contributes to aging and disease.
These molecules are normally controlled by antioxidants to prevent damage. Inside the cell are various organelles (illustrated below) – specialised components with different functions – which include so-called "peroxisomes". These play an important role in regulating the concentration of free oxygen radicals.
Prof. Cornelia Palivan and her research group at the University of Basel have successfully produced artificial peroxisomes that mimic the natural organelle. The researchers developed a cell organelle based on polymeric nanocapsules, in which two types of enzymes were encapsulated. These enzymes can transform free oxygen radicals into water and oxygen.
In order to verify the functionality inside the cell, channel proteins were added to the artificial peroxisome's membrane to serve as gates for substrates and products. The results show that the artificial peroxisomes are incorporated into the cell, where they support natural peroxisomes in a very efficient detoxification process.
By augmenting the internal functions of cells, these implants could pave the way to a new generation of novel drugs which make patient-oriented and personalised treatments possible in the future. The results of the study are published in the journal Nano Letters.
Using nanostructured glass, scientists at the University of Southampton have, for the first time, demonstrated the recording and retrieval processes of five dimensional digital data by femtosecond laser writing. The storage allows unprecedented parameters, including 360 TB/disc data capacity, thermal stability up to 1000°C and practically unlimited lifetime.
Coined as the 'Superman' memory crystal, as the glass memory has been compared to the "memory crystals" used in the Superman films, the data is recorded via self-assembled nanostructures created in fused quartz, which is able to store vast quantities of data for over a million years. The information encoding is realised in five dimensions: the size and orientation in addition to the three dimensional position of these nanostructures.
A 300 kb text file was successfully recorded in 5D using an ultrafast laser – producing extremely short and intense pulses of light. The file is written in three layers of nanostructured dots separated by five micrometres (one millionth of a metre). The self-assembled nanostructures change the way light travels through glass, modifying polarisation of light that can then be read by a combination of optical microscope and a polariser, similar to that found in Polaroid sunglasses.
The research is led by Jingyu Zhang at the Optoelectronics Research Centre (ORC) and conducted under a joint project with Eindhoven University of Technology.
"We are developing a very stable and safe form of portable memory using glass, which could be highly useful for organisations with big archives," says Jingyu. "At the moment, companies have to back up their archives every five to ten years because hard-drive memory has a relatively short lifespan. Museums who want to preserve information or places like the national archives where they have huge numbers of documents, would really benefit."
Professor Peter Kazansky, the ORC's group supervisor: "It is thrilling to think that we have created the first document which will likely survive the human race. This technology can secure the last evidence of civilisation: all we've learnt will not be forgotten."
The team presented their paper at the Conference on Lasers and Electro-Optics (CLEO'13) in San Jose. They are now looking for industry partners to commercialise this ground-breaking new technology.
Adding low doses of silver to antibiotics can make them up to 1,000 times more effective – offering a potential solution to the problem of drug-resistant bacteria.
Silver particles. Credit: Swiss Federal Laboratories for Materials Science and Technology (EMPA)
Old antibiotics could be given new life, according to a study by Harvard scientists, reported yesterday in the journal Science Translational Medicine. Treating bacteria with a silver-containing compound boosted the efficacy of a broad range of widely used antibiotics and helped them stop otherwise lethal infections in mice. It helped make an antibiotic-resistant strain of bacteria sensitive to antibiotics again. And it expanded the power of an antibiotic called vancomycin that is usually only effective in killing pathogens called Gram-positive bacteria, such as Staph and Strep. Silver allowed vancomycin for the first time to penetrate and kill Gram-negative bacteria, a group that includes microbes that can cause food poisoning and dangerous hospital-acquired infections.
Silver also proved useful for two types of stubborn infections that usually require repeated rounds of antibiotic treatment and multiple visits to the clinic: dormant bacteria that lie low during antibiotic treatment and rebound to cause recurrent infections, and microbial slime layers called biofilms that coat catheters and prosthetic joints.
Jim Collins, Ph.D., a pioneer of synthetic biology and Core Faculty member at Harvard's Wyss Institute: "The results suggest that silver could be incredibly valuable as an adjunct to existing antibiotic treatments."
In recent years, more disease-causing bacteria have grown resistant to common antibiotics, with serious consequences for public health. Yet drug companies have struggled to develop new types of antibiotics that target these tough bacteria.
That has led scientists to re-examine older methods that were used to fight infection well before penicillin use took off in the 1940s. Silver treatment, which has been used since antiquity to prevent and heal infections, is one of them.
Despite silver's long history of use in medicine, no one understood fully how it killed bacteria. To find out, Professor Ruben Morones-Ramirez treated normal and mutant strains of E. coli bacteria with a silver compound. He then observed them under the electron microscope and ran a series of biochemical tests.
He found that silver compounds cause bacteria to produce more reactive oxygen species – chemically reactive molecules that damage the bacterial cell's DNA and enzymes, as well as the membrane that encloses the cell. Silver also made the bacteria's cell membrane leakier.
Although silver was used alone as a therapy in the past, the scientists suspected that both changes might make cells more vulnerable to conventional antibiotics – and they did. A small amount of silver made E. coli bacteria between 10 and 1000 times more sensitive to three commonly used antibiotics: gentamycin, ofloxacin, and ampicillin.
"If you know the mechanism, you can have much more success making combinatorial therapies," Morones-Ramirez said.
Scanning electron micrograph of E. coli bacteria.
In mice, silver also helped antibiotics fight E. coli-induced urinary-tract infections. It made a previously impervious strain of E. coli sensitive to the antibiotic tetracycline. And it allowed vancomycin to save the lives of 90 percent of mice with life-threatening cases of peritonitis – inflammation caused by infections of the abdominal space surrounding internal organs. Without silver, only 10 percent of the mice survived.
The scientists also did a series of toxicity studies, showing that the doses of silver needed to help antibiotics kill bacteria were far below what could harm the mice. Nor did they harm cultured human cells, suggesting that oral and injectable silver could be safe for humans as well.
"Doctors desperately need new strategies to fight antibiotic-resistant infections, and Jim and his team have uncovered one that's incredibly versatile, and that could be put to use quickly in humans," said Don Ingber, M.D., Ph.D., Wyss Institute Founding Director.
"We're keen to explore how smart drug-delivery nanotechnologies being developed at the Wyss could help deliver effective but nontoxic levels of silver to sites of infection," Collins said.
Novel application of 3D printing could enable the development of miniaturised medical implants, compact electronics, tiny robots and more.
3D printing can now be used to print lithium-ion microbatteries the size of a grain of sand. The printed microbatteries could supply power to tiny devices in fields from medicine to communications, including many that have lingered on lab benches for lack of a battery small enough to fit the device, yet provide enough stored energy to power them.
To make the microbatteries, a team based at Harvard University and the University of Illinois at Urbana-Champaign printed precisely interlaced stacks of tiny battery electrodes – each less than the width of a human hair.
"Not only did we demonstrate for the first time that we can 3D-print a battery; we demonstrated it in the most rigorous way," said Professor Jennifer Lewis, senior author of the study.
In recent years, engineers have invented many miniaturised devices, including medical implants, flying insect-like robots, and tiny cameras and microphones that fit on a pair of glasses. But often, the batteries that power them are as large as or larger than the devices themselves, which defeats the purpose of building small.
To get around this problem, manufacturers have traditionally deposited thin films of solid materials to build the electrodes. However, due to their ultra-thin design, these solid-state micro-batteries do not pack sufficient energy to power tomorrow's miniaturised devices.
The scientists realised they could pack more energy by creating stacks of tightly interlaced, ultrathin electrodes that were built out of plane. For this, they turned to 3D printing. 3D printers follow instructions from 3D computer drawings, depositing successive layers of material – inks – to build a physical object from the ground up, much like stacking a deck of cards one at a time. This technique is used in a range of fields, from producing crowns in dental labs to rapid prototyping of aerospace, automotive, and consumer goods.
Lewis’ group has greatly expanded the capabilities of 3D printing. They have designed a broad range of functional inks – each with useful chemical and electrical properties. And they have used those inks with their custom-built 3D printers to create precise structures with the electronic, optical, mechanical, or biologically relevant properties they want.
To print 3D electrodes, Lewis' group first created and tested several specialised inks. Unlike the ink found in a typical office printer, which comes out as droplets of liquid that wet the page, the inks developed for extrusion-based 3D printing must fulfil two difficult requirements. They must exit fine nozzles like toothpaste from a tube, and they must immediately harden into their final form.
In this case, the inks also had to function as electrochemically active materials to create working anodes and cathodes, and they had to harden into layers as narrow as those produced by thin-film manufacturing. To accomplish these goals, the researchers created an ink for the anode with nanoparticles of one lithium metal oxide compound, and an ink for the cathode from nanoparticles of another. The printer deposited the inks onto the teeth of two gold combs, creating a tightly interlaced stack of anodes and cathodes. Then the researchers packaged the electrodes into a tiny container and filled it with an electrolyte solution to complete the battery.
Next, they measured how much energy could be packed into the tiny batteries, how much power they could deliver and how long they held a charge. “The electrochemical performance is comparable to commercial batteries in terms of charge and discharge rate, cycle life and energy densities – just on a much smaller scale,” said co-author Shen Dillon, Assistant Professor of Materials Science and Engineering.
“Jennifer’s innovative microbattery ink designs dramatically expand the practical uses of 3D printing, and simultaneously open up entirely new possibilities for miniaturisation of devices, both medical and non-medical. It’s tremendously exciting,” said Wyss Founding Director Donald Ingber.
A phase 1 clinical trial for the first treatment to "reset" the immune system of multiple sclerosis (MS) patients has shown that the therapy is safe. It dramatically reduced patients' immune systems' reactivity to myelin by 50 to 75 percent, according to new research.
In MS, the immune system attacks and destroys myelin, the insulating layer that forms around nerves in the spinal cord, brain and optic nerve. When the insulation is destroyed, electrical signals can’t be effectively conducted, resulting in symptoms that range from mild limb numbness to paralysis or blindness.
“The therapy stops autoimmune responses that are already activated and prevents activation of new autoimmune cells,” said Stephen Miller, Professor of Microbiology-Immunology at Northwestern University. “Our approach leaves the function of the normal immune system intact. That’s the holy grail.”
Miller is co-author of a paper on the study, published this week in Science Translational Medicine. The study is a collaboration between Northwestern’s Feinberg School, University Hospital Zurich in Switzerland and University Medical Centre Hamburg-Eppendorf in Germany.
The human trial is the result of more than 30 years of preclinical research in Miller's lab. In the trial, the MS patients’ own specially processed white blood cells were used to stealthily deliver billions of myelin antigens into their bodies so their immune systems would recognise them as harmless and develop tolerance to them. Current therapies for MS suppress the entire immune system – making patients more susceptible to everyday infections and higher rates of cancer.
Although the trial’s nine patients were too few to statistically determine the treatment’s ability to prevent the progression of MS, the study did show patients who received the highest dose of white blood cells had the greatest reduction in myelin reactivity. The primary aim of this study was to demonstrate the treatment’s safety and tolerability. It confirmed that injection of 3 billion white blood cells with myelin antigens caused no adverse affects. Most importantly, it did not reactivate the patients’ disease and did not affect their healthy immunity to everyday infections.
As part of the study, researchers tested the patients’ immunity to tetanus, because all had received tetanus shots during their lifetime. One month after the treatment, their immune responses to tetanus remained strong, showing that the treatment’s immune effect was specific only to myelin.
This safety study sets the stage for a phase 2 trial, to see if the new treatment can prevent the progression of MS. Scientists are currently trying to raise $1.5 million to launch the trial, which has already been approved in Switzerland. Using a biodegradable nanoparticle filled with myelin antigen, Miller’s pre-clinical research has already shown the treatment can stop progression of MS in mice, as reported last November.
Using a patient’s white blood cells is a costly and labour-intensive procedure. Miller’s study showed the nanoparticles, which are potentially cheaper and more accessible to a general population, could be as effective as the white blood cells as delivery vehicles. Furthermore, this therapy – with further testing – may be useful in treating not only MS, but also a host of other autoimmune and allergic diseases, simply by switching the antigens.
Electron microscopy images of Upsalite. Credit: Forsgren J, Frykstrand S, Grandfield K, Mihranyan A, Strømme M (2013)
