This
beats conventional methods
An ultrasensitive DNA sensor that can detect S.
pyogenes, a bacterium which causes a wide range of diseases in about
30 minutes has been developed. The DNA chip is highly specific device for S.
pyogenes. The conventional method of identification takes 18-24 hours
and the basic culture test does not specifically help distinguish S.
pyogenes.
Early
detection
From mild skin and throat infections to
life-threatening toxic shock syndrome, S. pyogenes infections
affect 700 million people every year. If not treated during early stages of the
infection, S. pyogenes can even lead to rheumatic heart
disease (heart valves damage).
The sensor was developed by scientists from
CSIR-Institute of Genomics and Integrative Biology (CSIR-IGIB) and National
Centre for Disease Control (NCDC) Delhi, and the results were published in the International
Journal of Biological Macromolecules.
The DNA chip based sensor consists of a carbon
electrode embedded with gold nanoparticles. By means of a bioinformatics study,
the researchers were able to design probes which are specific for S.
pyogenes.
The working electrode surface of the device is
attached with several small-sized, single-stranded DNA probe specific to the
pathogen. When patients’ DNA, isolated from throat swabs, are placed on the
surface, they bind to the complementary single-stranded DNA on the device and
an electrochemical change is seen. This is measured using a differential pulse
voltammetry.
Identification of pathogen
For confirmation, traditional culture test was used
and the results matched with the DNA sensor. “The sensor is highly sensitive
and could detect even 60-65 bacteria in a 6 microlitre sample. It could
identify the pathogen even at very low concentrations of DNA. We were able to
get a peak with a concentration of even 0.001nanogram per 6 microlitre,”
explains Swati Singh from IGIB and the first author of the paper.
Stable
sensor
The
sensor was found to be stable for 12 months with only 10% loss in initial
current peak on storage at 4 degree C. “We are working on construction of
different biosensors for different pathogens. Early and quick diagnosis can
help in preventing the diseases and seek medical treatment at the early stage
of infection,” adds Dr. Ashok Kumar, Chief Scientist/Professor (AcSIR) at IGIB
and corresponding author of the paper.
Source: THE HINDU-13th August,2017
