Scientists have coated paper with silver nanoparticles,
to create a 'killer paper' packaging that could lengthen the
shelf life of foods (Photo: Robin)
Silver is a known killer of harmful bacteria, and has already
been incorporated into things such as
antibacterial keyboards,
washing
machines,
water filters, and
plastic coatings for medical devices. Now, scientists have
added another potential product to the list: silver
nanoparticle-impregnated “killer paper" packaging, that could
help keep food from spoiling.
Led by Aharon Gedanken from Israel’s
Bar-Ilan University, the team discovered that paper could be
covered with silver nanoparticles through the application of
ultrasonic radiation – a process known as ultrasonication. It
involves the formation and subsequent collapse of acoustic
bubbles near a solid surface, which creates microjets that throw
the desired nanoparticles onto that surface. To the team’s
knowledge, this was only the second time that ultrasonication
had ever been attempted on paper.
Unlike previous attempts at creating antibacterial paper,
this one-step method was reportedly quite effective, and
produced a smooth, homogenous, long-lasting coating. By varying
the nanoparticle concentration and the application time, the
thickness of the coating could be varied as needed. When exposed
to E. coli and S. aureus bacteria, both of
which cause food poisoning, the paper killed them all off within
three hours.
The scientists stated that the ultrasonication process could
also be used to apply other nanomaterials to paper, which could
be used to tweak its hydrophobicity, conductivity, or texture.
While the addition of ionic silver to foods has been used in
the past to ward off bacteria, the paper would reportedly serve
as a longer-term solution, as it would act as a slow-release
reservoir for the silver. Germany’s Fraunhofer Institute for
Process Engineering and Packaging has previously looked into the
use of
sorbic acid-coated plastic as an antibacterial food wrap.
The killer paper research was recently published in the
journal
Langmuir.
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