Flu fighters are wired


Flu kills as many as half a million people each year

Flu kills as many as half a million people each year

Two strains of flu can be diagnosed in minutes from exhaled breath using a nanowire biosensor.1 The inventors hope that their device will revolutionise flu diagnosis and help to control disease outbreaks in the event of a pandemic.

Annual flu epidemics are dominated by two main strains and result in up to 5 million severe cases each year, with up to 500,000 deaths. The typical human seasonal influenza A is type H3N2 or H1N1, also known as swine flu. Given the ease of transmission of this disease, it would help clinicians to have a rapid and reliable diagnostic test.

Currently, the gold standard for diagnosis is the quantitative real time polymerase chain reaction in which RNA is extracted from respiratory fluids and amplified. This test takes several hours to complete and is not perfect, detecting non-infectious RNA and producing false negatives owing to low viral quantities and sampling problems.

Maosheng Yao and colleagues from Peking University and the University of Science and Technology, Beijing, China, have devised an alternative test, which is rapid enough for a clinical setting. It uses a biosensor made from a grid of silicon nanowires which have been functionalised with influenza A antibodies to trap proteins from the virus. Proteins that become trapped on the nanowires change the electrical conductance of the device in a manner that is proportional to viral concentration. ‘Once the sensing system is ready, the entire detection time is about 2 minutes,’ says Yao.

They have previously used a similar device for the real-time detection of airborne influenza viruses by continuous air sampling,2 but their new system is for exhaled breath. Patients breathe into a cooled collection device, the liquid is diluted 100-fold to eliminate potential interferences from other breath components before being applied to the sensor. The sensor is able to detect as little as 29 viruses/µL.

Accurate positive or negative diagnoses were given for 90% of cases tested. However, the test is not universal, says Euan Tovey from the University of Sydney Medical School, Australia, who studies human respiratory viruses in breath. ‘If you are interested in what people in a population coming to a clinic are infected with then these methods will not look too good, unless you have multiplexed sensors. However, if you have – or fear – a nascent pandemic on your hands and you know exactly what you are looking for and you have the antibodies, then you have a possible way to do this.’

The next stage is to automate the test. ‘We are working on a handheld device for nanowire virus detection and it is doable,’ Yao says. ‘In our laboratory, we already have the electronics ready that can assemble the electrical signals from the nanowire into a CPU system that can send the detection signal remotely.’

References

  1. F Shen et al, Nano Lett., 2012, DOI: 1021/nl301516z
  2. F Shen et al, Environ. Sci. Technol., 2011, 45, 7473 (DOI: 10.1021/es1043547)

Related Content

Rigid molecular wires make electrons fly

29 August 2014 Research

news image

Organic wires conduct electrons 800 times faster than other molecular counterparts by letting them hitch a ride on a vibratio...

Paving the way to polythene

11 October 2013 Premium contentFeature

news image

It is 50 years since Karl Ziegler and Giulio Natta won the Nobel prize for their work on polymers

Most Read

Higher levels of some metals in e-cigarette smoke

8 September 2014 Research

news image

Scientists call for regulators to help clear smoke and mirrors surrounding vaping safety

Isotope effect produces new type of chemical bond

22 October 2014 Research

news image

Evidence emerges for vibrational bond first proposed 30 years ago

Most Commented

Indian U-turn on diabetes drug ban

16 August 2013 News and Analysis

news image

Suspension of cheap and popular medicine reversed but will now come with new safety warnings

DNA waves don't wash

10 July 2013 The Crucible

news image

Philip Ball asks why a spectacular claim seems to have been overlooked. Sometimes science doesn’t work the way it’s suppo...