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article imagePortable DNA sequencer can detect pathogens

By Tim Sandle     Apr 5, 2015 in Science
A sophisticated palm-sized, nanopore-based portable device can recognize a range of pathogens, including E. coli, cowpox, and smallpox. The device is USB powered and it can be used out in the field by medics.
The innovative hand-held DNA sequencer can be used to differentiate specific strains of bacteria and viruses within six hours. The idea is to use the device in countries with weak health infrastructures and where medical centers are many miles away.
The device has been developed by a technology start-up called Oxford Nanopore Technologies. The device itself has been named MinION. It is one of the first practically working nanopore sequencing devices manufactured. The USB-powered sequencer contains thousands of cells, each containing nanopores. Nanopores are narrow channels that are so small that only one strand of DNA can fit into them (holes of the order of 1 nanometer.) As DNA enters the channels, each of the four molecular bases that make-up DNA - adenine, guanine, cytosine, and thymine - emits an electronic signature that can be detected by the system.
The theory behind nanopore sequencing is that when a nanopore is immersed in a conducting fluid and a voltage is applied across it, an electric current can be detected. The amount of current is sensitive to the size and shape of the nanopore. When strands of DNA pass through the nanopore, this creates a characteristic change in the magnitude of the current through the nanopore.
Through this the device provides a readout of the DNA sequence. Once a complete sequence has been compiled, the device can identify an array of pathogens.
To see how well the device detected diseases in remote areas, scientists based at the Edgewood Chemical Biological Center in Maryland, together with the Defense Threat Reduction Agency in Virginia, and the commercial company Signature Science, used the MinION to sequence known samples of amplified DNA from Escherichia coli bacteria and three poxviruses.
By amplifying the DNA before running it through the device, the scientists correctly identified E. coli. The scientists further discovered that the nanopore sequencing data could also be used to distinguish among types of cowpox.
The device has been described in detail in a paper published in the journal GigaScience. The paper is titled "Bacterial and viral identification and differentiation by amplicon sequencing on the MinION nanopore sequencer."
More about dna scanner, portable diagnostic device, Pathogens, Scanner
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