Suppressed activity of small molecules called microRNA has been linked to the onset of blood-borne cancers. This is because they target other RNA molecules and stop them coding for certain proteins, with their impairment previously been linked to the formation of tumors and metastasis. Scientists in Australia have now made a breakthrough they say will allow them to detect low microRNA levels in much smaller samples, so much so it could take just prick of the finger.

The new technique was developed by researchers at Australia's University of New South Wales (UNSW), who conducted experiments using gold-plated nanoparticles that had been modified with DNA, equipping them with the electrochemical signal to align with the microRNA they set out to detect.

These nanoparticles are likened to dispersible electrodes by the researchers. Distributing them into the blood samples saw them latch onto the targeted microRNA, which in turn makes the molecules much easier to collect and tally up as they can be extracted with a magnet. Capturing the microRNA in this way is said to be a marked improvement on how things are currently done using nucleic acid testing, cutting the waiting time from 12 hours to just 30 minutes.

"Now we get more of the microRNA because the dispersible electrodes capture nearly everything in the sample," said study co-author Professor Justin Gooding. "Because the capture is so effective, we get higher sensitivities and can detect much lower limits. And since we bring them back to the electrode under a magnet, our response time is much faster."

Making the process quicker also means that it will be cheaper. The greater sensitivity, meanwhile, also means that fluctuations in microRNA should be more easily detectable, in effect making it easier to determine a patient's risk factor for associated cancers.

"This is really important to determine whether the levels of different microRNAs have increased or decreased," Professor Gooding said. "We can do this very quickly compared with the gold-standard nucleic acid amplification methods. And we can do it in unprocessed blood. What this means is the technology has the potential to determine the levels of microRNA just from a finger prick test."

From here the scientists are exploring how the new technology could dovetail with another under development at UNSW, which relies on a malaria protein to detect early-stage cancer cells in the blood, with the targeted cells also retrieved using a magnet.

"The malaria protein technology works by detecting cancer cells, rare cells in particular," says Gooding. "These are found in the blood also and so are also compatible with the liquid biopsy concept. We are detecting small molecules found in the blood which could also identify the type of cancer, while they are looking for rare cells that are responsible for the spread of cancer. The two technologies could work very well together."

The research was published in the journal Nature Nanotechnology.

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