2nd February 2016
Graphene shown to safely interface with neurons in the brain
Researchers in Europe have demonstrated that graphene can be successfully interfaced with neurons, while maintaining the integrity of these vital nerve cells. It is believed this could lead to greatly improved brain implants.
A new study published in the journal ACS Nano demonstrates how it is possible to interface graphene with neurons, whilst maintaining the integrity of these vital nerve cells. The research was part of the EU's Graphene Flagship – a €1 billion project that aims to bring graphene from laboratories into commercial applications within 10 years. The study involved a collaboration between nanotechnologists, chemists, biophysicists and neurobiologists from the University of Trieste in Italy, the University Castilla-La Mancha in Spain and the Cambridge Graphene Centre in the UK.
Prof. Laura Ballerini, lead neuroscientist in the study: "For the first time, we interfaced graphene to neurons directly, without any peptide coating used in the past to favour neuronal adhesion. We then tested the ability of neurons to generate electrical signals known to represent brain activities and found that the neurons retained unaltered their neuronal signalling properties. This is the first functional study of neuronal synaptic activity using uncoated, graphene-based materials."
Using electron microscopy and immuno-fluorescence in rat brain cell cultures, the researchers observed that the neurons interfaced well with the untreated graphene electrodes – remaining healthy, transmitting normal electric impulses and, importantly, showing no adverse glial reaction which can lead to damaging scar tissue. This is therefore the first step towards using pristine, graphene-based material for a neuro-interface.
Graphene-based electrodes implanted in the brain could restore sensory functions for amputees or paralysed patients, or treat individuals with motor disorders such as epilepsy or Parkinson's disease. Further into the future, perhaps they could be used to enhance or upgrade the abilities of normal, healthy people too, bringing the age of transhumanism closer to reality.
Too often, the modern electrodes used for neuro-interfaces (based on tungsten or silicon) suffer partial or complete loss of signal over time. This is often caused by scar tissue formation during the electrode insertion and by its rigid nature preventing the electrode from moving with the natural movements of the brain. Graphene, by contrast, appears to be a highly promising material to solve these problems. It has excellent conductivity, flexibility, biocompatibility and stability within the body.
"Hopefully this will pave the way for better deep brain implants to both harness and control the brain, with higher sensitivity and fewer unwanted side effects," said Ballerini.
"These initial results show how we are just at the tip of the iceberg when it comes to the potential of graphene and related materials in bio-applications and medicine," said Professor Andrea Ferrari, Director of the Cambridge Graphene Centre. "The expertise developed at the Cambridge Graphene Centre allows us to produce large quantities of pristine material in solution, and this study proves the compatibility of our process with neuro-interfaces."
21st January 2016
Nanoparticles kill 90% of antibiotic-resistant bacteria
Light-activated nanoparticles able to kill over 90% of antibiotic-resistant bacteria have been demonstrated at the University of Colorado.
Salmonella bacteria under a microscope. Photo by NIAID / Wikipedia.
Antibiotic-resistant bacteria such as Salmonella, E. Coli and Staphylococcus infect some two million people and kill 23,000 in the U.S. each year. Efforts to defeat these so-called "superbugs" have consistently fallen short, due to the bacteria's ability to adapt rapidly and develop immunity to common antibiotics such as penicillin. In 2014, the World Health Organisation declared this a "major global threat" and warned that the world is heading for a post-antibiotic era, in which even common infections and minor injuries which have been treatable for decades can once again kill.
In this ever-escalating evolutionary battle with drug-resistant bacteria, we may soon have an advantage, however, thanks to adaptive, light-activated nanotherapy developed by scientists at the University of Colorado Boulder. Their latest research suggests that the solution to this big global problem might be to think small – very small.
In findings published by the journal Nature Materials, researchers at the Department of Chemical and Biological Engineering and the BioFrontiers Institute describe new light-activated nanoparticles known as "quantum dots." These dots, which are 20,000 times smaller than a human hair and resemble the tiny semiconductors used in consumer electronics, successfully killed 92% of drug-resistant bacterial cells in a lab-grown culture.
"By shrinking these semiconductors down to the nanoscale, we're able to create highly specific interactions within the cellular environment that only target the infection," said Prashant Nagpal, senior author of the study.
Credit: University of Colorado Boulder / BioFrontiers Institute
Previous research has shown that metal nanoparticles – created from silver and gold, among various other metals – can be effective at combating antibiotic resistant infections, but can indiscriminately damage surrounding cells as well. Quantum dots, however, can be tailored to particular infections thanks to their light-activated properties. The dots remain inactive when in darkness, but can be "activated" on command by exposing them to light, allowing researchers to modify the wavelength in order to alter and kill the infected cells.
"While we can always count on these superbugs to adapt and fight the therapy, we can quickly tailor these quantum dots to come up with a new therapy and therefore fight back faster in this evolutionary race," said Nagpal.
The specificity of this innovation may help reduce or eliminate the potential side effects of other treatment methods, as well as provide a path forward for future development and clinical trials.
"Antibiotics are not just a baseline treatment for bacterial infections, but HIV and cancer as well," said Anushree Chatterjee, an assistant professor in the Department of Chemical and Biological Engineering at CU-Boulder and a senior author of the study. "Failure to develop effective treatments for drug-resistant strains is not an option, and that's what this technology moves closer to solving."
Nagpal and Chatterjee are co-founders of PRAAN Biosciences, a Colorado-based startup that can sequence genetic profiles using just a single molecule – technology that may aid in the diagnosis and treatment of superbug strains. The authors have filed a patent on their new quantum dot technology.
19th December 2015
New microscope is 2,000 times faster
A new atomic force microscope developed by MIT can scan images 2,000 times faster than existing commercial models. This allows it to capture near-real-time video of nanoscale processes.
State-of-the-art atomic force microscopes (AFMs) are designed to capture images of structures as small as a fraction of a nanometre – a million times smaller than the width of a human hair. In recent years, AFMs have produced desktop-worthy close-ups of atom-sized structures, from DNA strands to individual bonds changing between molecules. But scanning these images is a meticulous, time-consuming process. AFMs have therefore been used mostly for static samples as they are too slow to capture active, changing environments.
Now engineers at MIT have designed an atomic force microscope that scans images 2,000 times faster than existing commercial models. With this new high-speed instrument, the team produced images of chemical processes taking place at the nanoscale, at a rate that is close to real-time video.
In one demonstration of the instrument’s capabilities, the researchers scanned a 70- by-70-micron sample of calcite as it was first immersed in deionised water and later exposed to sulphuric acid. Zooming into an area of interest, they observed the acid eating away at the calcite, expanding existing nanometre-sized pits in the material that quickly merged and led to a layer-by-layer removal of calcite along the material’s crystal pattern, over a period of several seconds.
Calcite immersed in deionised water.
Sulphuric acid creating pits in the calcite.
Professor of Mechanical Engineering at MIT, Kamal Youcef-Toumi, says the instrument’s sensitivity and speed will enable scientists to watch atomic-sized processes play out as high-resolution “movies.”
“People can see, for example, condensation, nucleation, dissolution, or deposition of material, and how these happen in real-time – things that people have never seen before,” he says. “This is fantastic to see these details emerging. And it will open great opportunities to explore all of this world that is at the nanoscale.”
The MIT researchers' achievement was made possible through an innovative new technique. This involved controlling the movement of the needle over the sample surface with two actuators (a small, fast scanner and a larger, slower one) in combination with a set of algorithms to ensure they never interfered with each other. At present, this method provides scans at eight to 10 frames per second, but further research is underway to increase this.
“We want to go to real video, which is at least 30 frames per second,” Youcef-Toumi says. “Hopefully we can work on improving the instrument and controls so that we can do video-rate imaging while maintaining its large range and keeping it user-friendly. That would be something great to see.”
The team's design and images, which are based on the PhD work of Iman Bozchalooi – now a postdoc in the Department of Mechanical Engineering – appear in the journal Ultramicroscopy.
19th November 2015
Nanosubmarines powered by light
Nano-scale submarines built from 244 atoms and capable of moving at 2 cm per second have been demonstrated by Rice University.
Credit: Loïc Samuel/Rice University
In a study published by Nano Letters, scientists from Rice University in Texas describe how they built and tested nanoscale submarines, which are able to move with incredible speed. The single-molecule, 244-atom submersibles each have a motor powered by ultraviolet light. With each full revolution the motor's tail-like propeller drives the sub forwards a distance of 18 nanometres (nm). However, the motors run at over a million RPM, giving a top speed of nearly two centimetres (0.8 inches) per second: a breakneck pace on the molecular scale.
"These are the fastest-moving molecules ever seen in solution," says chemist James Tour, one of the study authors.
While they can't be steered yet, the study has proved that molecular motors are powerful enough to drive the sub-10-nanometre craft through solutions of moving molecules of about the same size.
From a nano-scale point of view, "this is akin to a person walking across a basketball court with 1,000 people throwing basketballs at him," Tour said.
Tour's group has extensive experience with molecular machines. A decade ago, his lab demonstrated nanocars – single-molecule cars with four wheels, axles and independent suspensions that could be "driven" across a surface. Over the years, many research groups have created microscopic machines featuring motors – but most have either used or generated toxic chemicals. A motor conceived in the last decade by Dutch researchers proved suitable for the Rice submersibles, which were produced in a 20-step chemical synthesis.
"These motors are well-known and used for different things," said Victor García-López, lead author and Rice graduate student. "But we were the first to propose they can be used to propel nanocars – and now submersibles."
Credit: Victor García-López/Rice University
The motors, which operate more like a bacteria's flagellum than a propeller, complete each revolution in four steps. When excited by light, the double bond that holds the rotor to the body becomes a single bond, allowing it to rotate a quarter step. As the motor seeks to return to a lower energy state, it jumps adjacent atoms for another quarter turn. This process repeats as long as the light is on. Once built, the team turned to Gufeng Wang at North Carolina State University to measure how well the nanosubs moved.
"We had used scanning tunnelling microscopy and fluorescence microscopy to watch our cars drive, but that wouldn't work for the submersibles," explained Tour. "They would drift out of focus pretty quickly."
The North Carolina team sandwiched a drop of diluted acetonitrile liquid containing a few nanosubs between two slides, then used a custom confocal fluorescence microscope to hit it from opposite sides with both ultraviolet light (for the motor) and a red laser (for the pontoons). The microscope's laser defined a column of light in the solution, in which tracking occurred, García-López said: "That way, the NC State team could guarantee it was analysing only one molecule at a time."
The team hopes future nanosubs will be able to carry cargoes for medical and other purposes. "There's a path forward," García-López said. "This is the first step, and we've proven the concept. Now we need to explore opportunities and potential applications."
18th October 2015
New crystal captures carbon from humid gas
A new material with micropores might be a way to fight climate change. Scientists have created crystals that capture carbon dioxide much more efficiently than previously known materials, even in the presence of water.
One way to mitigate climate change could be to capture carbon dioxide (CO2) from the air. So far this has been difficult, since the presence of water prevents the adsorption of CO2. Complete dehydration is a costly process. Scientists have now created a stable and recyclable material, where the micropores within the crystal have different adsorption sites for carbon dioxide and water.
“As far as I know, this is the first material that captures CO2 in an efficient way in the presence of humidity,” says Osamu Terasaki, Professor at the Department of Materials and Environmental Chemistry at Stockholm University. “In other cases, there is competition between water and carbon dioxide and water usually wins. This material adsorbs both, but the CO2 uptake is enormous.”
The new material is called SGU-29, named after Sogang University in Korea, and is the result of international cooperation. It is a copper silicate crystal that forms two nanotube regions – one hydrophobic and one hydrophilic – repelling water while trapping carbon dioxide. The material could be used for capturing carbon directly from the atmosphere, and especially to clean emissions from power plants or other sources.
“CO2 is always produced with moisture, and now we can capture CO2 from humid gases. Combined with other systems that are being developed, the waste carbon can be used for new valuable compounds. People are working very hard and I think we will be able to do this within five years. The most difficult part is to capture carbon dioxide, and we have a solution for that now,” concludes Terasaki.
Major advances in carbon capture and storage will be needed if the world is to avoid 2°C or higher of global warming. Current emission plans by the world's nations ahead of the UN climate change conference in Paris next month fall well short of what is truly needed. Materials such as that demonstrated by Terasaki could pave the way towards a new generation of cheaper, more efficient and widespread carbon sequestration in the coming years and decades. His team's research is published this week in the journal Science.