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STRONG QC &
STRONG QC & QAQA

of the droplets’ multivalency to before shipping the food, to scan and test it to make sure it’s safe.”
increase the binding affinity, and The researchers are now working on optimizing the food sample preparation so they can be
this is something that is very placed into the wells with the droplets. They also plan to create droplets customized with more complex
different than what other sensors sugars that would bind to different bacterial proteins. In this paper, the researchers used a sugar that
are using. binds to a nonpathogenic type of E. coli, but they expect that they could adapt the sensor to other
To demonstrate how these strains of E. coli and other harmful bacteria. “You could imagine making really selective droplets to
droplets could be used for sensing, catch different bacteria, based on the sugar we put on them,” Savagatrup says.
the researchers placed them into The researchers are also trying to improve the sensitivity of the sensor, which currently is similar
a Petri dish atop a QR code that to existing techniques but has the potential to be much greater, they believe. They hope to launch a
can be scanned with a smartphone. company to commercialize the technology within the next year and a half.
When E. coli are present, the
droplets clump together and the
QR code can’t be read.
Chad Mirkin, a professor of
chemistry at Northwestern
University and director of the
International Institute for
Nanotechnology, described the
particles as a powerful new class
of assays. “They are elegantly
simple but rely on clever new
approaches to making and
manipulating emulsions,” says
Mirkin, who was not involved in
the research. “This proof-of-
concept demonstration in
detecting foodborne pathogens is
compelling, as they constitute a
major class of analytes that
defines an unmet need in the
biosensor community.”
Faster and cheaper
Current food safety testing often
involves placing food samples in
a culture dish to see if harmful
bacterial colonies form, but that
process takes two to three days.
More rapid techniques based on
bacterial DNA amplification or
antibody-bacteria interactions are
expensive and require special
instruments.
The MIT team hopes to adapt
its new technology into arrays of
small wells, each containing
droplets customized to detect a
different pathogen and linked to a
different QR code. This could
enable rapid, inexpensive
detection of contamination using
only a smartphone.
“The great advantage of our
device is you don’t need
specialized instruments and
technical training in order to do
this,” Zhang says. “That can
enable people from the factory,

SEP 2018 FOOD FOCUS THAILAND 45