A smart universal tool based on a simplified DNA
barcoding technique combined with nanotechnology
enables food authentication with the naked eye.
Is the food on the shelf
really that what is written on the label?
Its DNA would give it away, but the DNA barcoding
technology, which can be used for this purpose, is
Now, in the journal
Angewandte Chemie, Italian scientists have
introduced a simplified assay coined NanoTracer.
Combining DNA barcoding with nanotechnology, it
requires neither expensive tools nor extremely
skilled personnel, but just the naked eye to
identify a color change.
The DNA barcoding
technology identifies an organism by a short unique
DNA sequence, the "barcode".
This barcode used for animal species-and thus for
meat products-is the sequence of a gene of
mitochodria, which are cell organelles.
Its sequence tells the
examiner if the product on the shelf contains
exactly the species that is declared on the label,
not a substituted or a diluted one.
However, DNA barcoding
requires elaborate procedures and takes time.
Therefore, Pier Paolo
Pompa at the Italian Institute of Technology IIT,
Genoa, and his colleagues from University of
Milano-Bicocca (M. Labra), Italy, have developed a
much simpler version of the test, termed NanoTracer,
which requires fewer and cheaper reagents, scarce
instrumentation, and features a simple color change
as its output.
Its main concept is the
reduction of the long barcode regions to short
subregions, in which the species nevertheless show
Shorter sequences have the advantage that even DNA
can be identified that is no longer intact—as it
happens in finished foods.
The short sequences are
then amplified by a polymerase chain reaction
This step includes the
The authors explain: "Our assay includes a universal
sequence, which serves to prime the aggregation of
(universal) DNA-functionalized gold nanoparticles,
with consequent red-to-violet color change."
Or, in other words, if
the sample DNA sequence matches that of the
simplified barcode primers, the respective DNA
segment is amplified, and the added nanogold agent
aggregates, turning the test solution's color from
red to violet.
Using their assay, the
scientists tested European perch, which is often
substituted by cheaper fish species, and saffron
powder, a high-value spice, which is frequently
diluted with other herbs for economic gain.
Both products were
distinctly identified with NanoTracer, and the
presence of substitutes or cheaper diluents was
As the authors point
out, their simplified assay is rapid (it takes less
than three hours) and sensitive, uses raw food
material, is parallelizable, involves simple
low-cost technology and materials, and thus can be
performed in decentralized simple laboratories at
For more information
DNA Barcoding Meets Nanotechnology: Development of a
Universal Colorimetric Test for Food Authentication
Pier Paolo Pompa et al., Angewandte Chemie
International Edition, 10.1002/anie.201702120