Wednesday, 23 April 2014
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How nanotechnology is revolutionising medical diagnostics

Much of the hype around nanotechnology has concentrated on its more outlandish medical applications, with the prospect of tiny cell-sized nanobots, telepathy chips and the ability to manipulate materials at the molecular level arousing wonder and concern in equal measure.

But while many have raised concerns about the safety and consequences of the technology, others believe the field is misunderstood. Indeed, according to Sotiris Pratsinis, a professor of particle technology at the Institute of Process Engineering at ETH Zurich, this public backlash against nanotechnology is misguided given the increasingly positive role that it could play in society.

’Nano was used by medieval artists to create magnificent colours in their art and it has been in chemistry much longer than people think,’ he said. ’Unlike some other areas of technology, it’s not a bubble that will burst because it’s always been with us. It’s only now that we are gaining the capacity to control it and it’s a formula that we’re still learning.’

Pratsinis and his colleagues at ETH Zurich are part of a wave of researchers attempting to understand the science behind nanoscale particles. Their work focuses on the emerging use of nanotechnology in medical diagnosis through the analysis of chemicals found in the breath.

Last month, the team unveiled a breath sensor that is able to instantly determine whether a person is suffering from type-one diabetes. ’The breath is made up of a mixture of nitrogen, carbon dioxide, oxygen and water, along many other volatile substances that exist only in very small amounts,’ said Pratsinis. ’These substances include more than 1,000 volatile organic compounds that are produced by the body and act as markers for a certain illness… For type-one diabetes, the typical marker is acetone.’

A recently launched breath sensor is able to determine whether a person is suffering from type-one diabetes

Acetone is found in healthy people’s breath at a concentration of around 900 particles per billion (ppb). This concentration doubles for people suffering from type-one diabetes and can be even higher in a potentially lethal condition known as ’ketoacidosis’ that occurs owing to a lack of insulin. The sensor has already shown that it can detect as few as 20ppb of acetone and is able to work at very high humidity levels of more than 90 per cent.

According to Pratsinis, the sensor could help patients monitor their condition before it gets to a critical stage. ’This is an exciting development,’ he said. ’Right now, we’re using blood samples, which is quite a primitive method. There are plenty of other bodily fluids that could be analysed and we haven’t taken advantage of that because, up until now, we just didn’t have the appropriate analytics.’

While a lack of understanding about the effects of nanoscale materials in the body continues to cause concern, for Pratsinis and his research colleagues the benefits outweigh the risks. ’With our sensor, you can reduce the time it takes to diagnose a patient from several days to several seconds,’ he said. ’The medical industry is battling spiralling costs at the moment and the only way we can reduce that is with better engineering.’

“The medical sector is battling spiralling costs and the only way we can reduce that is with better engineering”
SOTIRIS PRATSINIS, ETH ZURICH

The sensor is made up of gold electrodes coated with a film of tungsten oxide and silicon nanoparticles. When the sensor comes into contact with breath, acetone molecules get caught up in the pores of the coating and begin to react with the tungsten oxide nanoparticles. If the breath contains relatively high acetone concentrations (more than 1,800ppb), the electrical resistance of the material drops. This causes more electricity to flow between the electrodes, generating a stronger signal from the device.

’There should be opportunities in the future where we will develop more materials to detect a range of illnesses,’ said Pratsinis. ’Right now, we’re focusing on developing a portable system for the sensor that would be both quick and user friendly. Hopefully, such a device will help to reduce the costs of medical services as well as encourage people to look after their health.’

Meanwhile, UK company Applied Nanodetectors claims to have come up with a solution that will do both. The Enfield-based group is proposing to use nanomaterial breath sensors embedded in mobile phones to provide asthmatic patients with the ability to monitor their condition from an adapted handset.

The idea is that a patient blows into a small hole at the top of his or her mobile phone, where a carbon nanotube and silicon-based sensor will be able to detect the amount of nitric oxide in their breath. After a few seconds, a traffic-light warning system will come on to indicate high levels of nitric oxide and help warn of an asthma attack. This data can be sent via the mobile phone to a healthcare server, automatically updating the patient’s records and alerting a doctor if necessary.

’The technology is ready, but one of the biggest challenges is developing the infrastructure for all the data,’ explained Victor Higgs, chief executive of Applied Nanodetectors. ’You can imagine if a diagnostic tool becomes credible, there will be a huge amount of information. But with the right systems in place, it could be possible for you to monitor your health at home and automatically integrate that data with the tests done at a doctor’s surgery.’

“The technology is ready, but one of the biggest challenges is developing the infrastructure for all the data.” VICTOR HIGGS, APPLIED NANODETECTORS

In the next few years, Higgs believes there will be a surge of early-stage work being moved into the development phase. ’Now, more and more of these materials are available and the quality of these materials has improved a lot over the past five years,’ he said. ’The manufacturing process and the production capability will also improve and, once it does, the technology will become more readily available.’

Pratsinis believes that another major barrier to the implementation of nanosensor technology is public perception. Not only is there a question mark about the effects of manipulating nano-sized particles, there also remain ethical and cultural barriers in shifting healthcare monitoring away from specialists and to the individual.

But with the increasingly frequent announcements of breakthroughs in this area, it seems that a mobile phone that can detect fatal diseases might be available sooner than we think.

PSA test good as gold

Mini machines: Cell-sized nanobots are, as yet, a hypothetical nanotechnology concept

Mini machines: Cell-sized nanobots are, as yet, a hypothetical nanotechnology concept

A nanotechnology-based blood test that is claimed to be far more sensitive than existing tests for prostate cancer is being developed by US researchers.

Scientists at Northwestern University’s Feinberg School of Medicine in Chicago are using gold nanoparticles coated with antibodies that track down and attach to bits of prostate-specific antigen (PSA) in the blood. The test, known as VeriSens PSA, was developed using frozen blood taken from men after prostate surgery.

According to the researchers, the gold nanoparticles mean that the new test is around 300 times better than the current PSA test at identifying whether prostate cancer has been cured or is likely to return.

Its ability to detect very low levels of PSA could mean that doctors will be able to diagnose men with prostate cancer recurrence years earlier.

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