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Scientists create the world's thinnest gold

Scientists create the world’s thinnest gold

Scientists at the University of Leeds have created a new form of gold which is just two atoms thick – the thinnest unsupported gold ever created.

The researchers measured the thickness of the gold to be 0.47 nanometres – one million times thinner than a human fingernail.

The material is regarded as 2D because it comprises just two layers of atoms sitting on top of one another. All atoms are surface atoms, there are no ‘bulk’ atoms hidden beneath the surface.

It could have wide-scale applications in the medical device and electronics industries, and also as a catalyst to speed up chemical reactions in a range of industrial processes.

Laboratory tests show that the ultra-thin gold is 10 times more efficient as a catalytic substrate than the larger gold nanoparticles currently used in industry.

‘Landmark achievement’

Scientists believe the new material could also form the basis of artificial enzymes for potential use in rapid, point-of-care medical diagnostic tests and in water purification systems.

The announcement that the ultra-thin metal had been successfully synthesised was made in Advanced Science. The journal paper’s lead author, Dr Sunjie Ye, from Leeds’ Molecular and Nanoscale Physics Group and the Leeds Institute of Medical Research, said: “This work amounts to a landmark achievement.
“Not only does it open up the possibility that gold can be used more efficiently in existing technologies, it is providing a route which would allow material scientists to develop other 2D metals.”This method could innovate nanomaterial manufacturing.”

The research team is looking to work with industry on ways of scaling-up the process.

…industry could get the same effect from using a smaller amount of gold, and this has economic advantages…

PROFESSOR STEPHEN EVANS

Synthesising the gold nanosheet takes place in an aqueous solution and starts with chloroauric acid, an inorganic substance that contains gold. It is reduced to its metallic form in the presence of a “confinement agent” – a chemical that encourages the gold to form as a sheet just two atoms thick.

Because of the gold’s nanoscale dimensions, it appears green in water, and given its frond-like shape, the researchers describe it as gold nanoseaweed.

Images taken from an electron microscope reveal the way the gold atoms have formed into a highly organised lattice structure.

Image shows a picture from an electron microscope showing tightly packed atoms

This electron microscope picture shows the gold atoms’ lattice structure(Credit: University of Leeds)

Professor Stephen Evans heads the Leeds’ Molecular and Nanoscale Research Group and supervised the research. He said the considerable gains that could be achieved from using ultra-thin gold sheets were down to their high surface-area-to-volume ratio.

“Gold is a highly effective catalyst. Because the nanosheets are so thin, just about every gold atom plays a part in the catalysis. It means the process is highly efficient.

“Our data suggests that industry could get the same effect from using a smaller amount of gold, and this has economic advantages when you are talking about a precious metal.”

The flakes are also flexible, meaning they could form the basis of electronic components for bendable screens, electronic inks and transparent conducting displays.

Image shows Dr Sunjie Ye and Professor Stephen Evans at a machine that analyses gold particle.

Dr Sunjie Ye and Professor Stephen Evans used x-ray photo electron spectroscopy to confirm the purity of the new form of gold. (Credit: University of Leeds)

Professor Evans thinks there will inevitably be comparisons made between the 2D gold and the first 2D material ever created – graphene, which was fabricated at the University of Manchester in 2004.

He said: “The translation of any new material into working products can take a long time and you can’t force it to do everything you might like to. With graphene, people have thought that it could be good for electronics or for transparent coatings, or as carbon nanotubes that could make an elevator to take us into space because of its super strength.

“I think with 2D gold we have got some very definite ideas about where it could be used, particularly in catalytic reactions and enzymatic reactions. We know it will be more effective than existing technologies – so we have something that we believe people will be interested in developing with us.”

Journal Reference: Advanced Science

Materials provided by the University of Leeds

‘Tickle’ therapy could help slow ageing

‘Tickle’ therapy could help slow ageing

‘Tickling’ the ear with a small electrical current appears to rebalance the autonomic nervous system for over-55s, potentially slowing down one of the effects of ageing, according to new research.

Scientists found that a short daily therapy delivered for two weeks led to both physiological and wellbeing improvements, including a better quality of life, mood and sleep.

The therapy, called transcutaneous vagus nerve stimulation (tVNS), delivers a small, painless electrical current to the ear, which sends signals to the body’s nervous system through the vagus nerve.

The new research, conducted at the University of Leeds, suggests the therapy may slow down an important effect associated with ageing.

This could help protect people from chronic diseases which we become more prone to as we get older, such as high blood pressure, heart disease and atrial fibrillation.

The researchers, who published their findings today in the journal Aging, suggest that the ‘tickle’ therapy has the potential to help people age more healthily, by recalibrating the body’s internal control system.

Lead author Dr Beatrice Bretherton, from the School of Biomedical Sciences at the University of Leeds, said: “The ear is like a gateway through which we can tinker with the body’s metabolic balance, without the need for medication or invasive procedures. We believe these results are just the tip of the iceberg.

“We are excited to investigate further into the effects and potential long-term benefits of daily ear stimulation, as we have seen a great response to the treatment so far.”

Dr Beatrice Bretherton sets up the tickle therapy on a volunteer

Dr Beatrice Bretherton sets up the tVNS therapy for a volunteer

The study was conducted by scientists from the University of Leeds and funded by the Dunhill Medical Trust.

What is the autonomic nervous system?

The autonomic nervous system controls many of the body’s functions which don’t require conscious thought, such as digestion, breathing, heart rate and blood pressure.

It contains two branches, the sympathetic and the parasympathetic, which work against each other to maintain a healthy balance of activity.

The sympathetic branch helps the body prepare for high intensity ‘fight or flight’ activity, whilst the parasympathetic is crucial to low intensity ‘rest and digest’ activity.

We believe this stimulation can make a big difference to people’s lives, and we’re now hoping to conduct further studies to see if tVNS can benefit multiple disorders.

DR SUSAN DEUCHARS

As we age, and when we are fighting diseases, the body’s balance changes such that the sympathetic branch begins to dominate. This imbalance makes us more susceptible to new diseases and leads to the breakdown of healthy bodily function as we get older.

Clinicians have long been interested in the potential for using electrical currents to influence the nervous system. The vagus nerve, the major nerve of the parasympathetic system, has often been used for electrical stimulation and past research has looked at the possibility of using vagus nerve stimulation to tackle depression, epilepsy, obesity, stroke, tinnitus and heart conditions.

However, this kind of stimulation needs surgery to implant electrodes in the neck region, with associated expense and a small risks of side effects.

Fortunately, there is one small branch of the vagus nerve that can be stimulated without surgery, located in the skin of specific parts of the outer ear.

In Leeds, previous research has shown that applying a small electrical stimulus to the vagus nerve at the ear, which some people perceive as a tickling sensation, improves the balance of the autonomic nervous system in healthy 30-year-olds.

Other researchers worldwide are now investigating if this transcutaneous vagus nerve stimulation could provide a therapy for conditions ranging from heart problems to mental health.

Diane Crossley, study participant, smiles in the sunshine

Diane Crossley (pictured above), aged 70, from Leeds, took part in the study and received the tVNS therapy for two weeks. She said: “I was happy to be a participant in this really interesting study, it helped me with my awareness of my own health.

“It was a fascinating project and I was proud to be part of it.”

In their new study, scientists at the University of Leeds wanted to see whether tVNS could benefit over 55-year-olds, who are more likely to have out-of-balance autonomic systems that could contribute to health issues associated with ageing.

They recruited 29 healthy volunteers, aged 55 or above, and gave each of them the tVNS therapy for 15 minutes per day, over a two week period. Participants were taught to self-administer the therapy at home during the study.

The therapy led to an increase in parasympathetic activity and a decrease in sympathetic activity, rebalancing the autonomic function towards that associated with healthy function. In addition, some people reported improvements in measures of mental health and sleeping patterns.

Being able to correct this balance of activity could help us age more healthily, as well as having the potential to help people with a variety of disorders such as heart disease and some mental health issues.

Additionally, improving the balance of the autonomic nervous system lowers an individual’s risk of death, as well as the need for medication or hospital visits.

Researchers found that individuals who displayed the greatest imbalance at the start of the study experienced the most pronounced improvements after receiving the therapy.

They suggest that in future it may be possible to identify who is most likely to benefit from the therapy, so it can be offered through a targeted approach.

tVNS therapy has previously been shown to have positive psychological effects for patients with depression, and this study shows it could also have significant physiological benefits.

Dr Susan Deuchars, one of the senior authors on the study, said: “We believe this stimulation can make a big difference to people’s lives, and we’re now hoping to conduct further studies to see if tVNS can benefit multiple disorders.”

Further studies are now needed to understand what the long-term health effects of tVNS might be, as this study involved a small number of participants over a short time period.

Materials provided by the University of Leeds

A miniature robot that could check colons for early signs of disease

A miniature robot that could check colons for early signs of disease

Engineers have shown it is technically possible to guide a tiny robotic capsule inside the colon to take micro-ultrasound images.

Known as a Sonopill, the device could one day replace the need for patients to undergo an endoscopic examination, where a semi-rigid scope is passed into the bowel – an invasive procedure that can be painful.

Micro-ultrasound images also have the advantage of being better able to identify some types of cell change associated with cancer.

The Sonopill is the culmination of a decade of research by an international consortium of engineers and scientists. The results of their feasibility study are published today in the journal Science Robotics.

The technology has the potential to change the way doctors conduct examinations of the gastrointestinal tract.

PROFESSOR PIETRO VALDASTRI

The consortium has developed a technique called intelligent magnetic manipulation. Based on the principle that magnets can attract and repel one another, a series of magnets on a robotic arm that passes over the patient interacts with a magnet inside the capsule, gently manoeuvring it through the colon.

The magnetic forces used are harmless and can pass through human tissue, doing away with the need for a physical connection between the robotic arm and the capsule.

An artificial intelligence system (AI) ensures the smooth capsule can position itself correctly against the gut wall to get the best quality micro-ultrasound images. The feasibility study also showed should the capsule get dislodged, the AI system can navigate it back to the required location.

Professor Pietro Valdastri, who holds the Chair in Robotics and Autonomous Systems in Leeds’ School of Electronic and Electrical Engineering and was senior author of the paper, said: “The technology has the potential to change the way doctors conduct examinations of the gastrointestinal tract.

“Previous studies showed that micro-ultrasound was able to capture high-resolution images and visualise small lesions in the superficial layers of the gut, providing valuable information about the early signs of disease.

“With this study, we show that intelligent magnetic manipulation is an effective technique to guide a micro-ultrasound capsule to perform targeted imaging deep inside the human body.

“The platform is able to localise the position of the Sonopill at any time and adjust the external driving magnet to perform a diagnostic scan while maintaining a high-quality ultrasound signal. This discovery has the potential to enable painless diagnosis via a micro-ultrasound pill in the entire gastrointestinal tract.”

Sandy Cochran, Professor of Ultrasound Materials and Systems at the University of Glasgow and lead researcher, said: “We’re really excited by the results of this feasibility study. With an increasing demand for endoscopies, it is more important than ever to be able to deliver a precise, targeted, and cost-effective treatment that is comfortable for patients.

“Today, we are one step closer to delivering that.

“We hope that in the near future, the Sonopill will be available to all patients as part of regular medical check-ups, effectively catching serious diseases at an early stage and monitoring the health of everyone’s digestive system.”

 

The Sonopill is a small capsule – with a diameter of 21mm and length of 39mm, which the engineers say can be scaled down. The capsule houses a micro ultrasound transducer, an LED light, camera and magnet.

A very small flexible cable is tethered to the capsule which also passes into the body via the rectum and sends ultrasound images back to a computer in the examination room.

The feasibility tests were conducted on laboratory models and in animal studies involving pigs.

Diseases of the gastrointestinal tract account for approximately 8 million deaths a year across the world, including some bowel cancers which are linked with high mortality.

The research was funded by the Engineering and Physical Sciences Research Council, the Royal Society and the US National Institutes of Health.

Materials Provided by the University of Leeds