Nanoparticles
are used in a wide range of products and manufacturing processes because the
properties of a material can change dramatically when the material comes in
nano-form.
They can
be used, for example, to purify wastewater and to transport medicine around the
body. They are also added to, for example, socks, pillows, mattresses, phone
covers and refrigerators to supply the items with an antibacterial surface.
Much
research has been done on how nanoparticles affect humans and the environment
and a number of studies have shown that nanoparticles can disrupt or damage our
cells.
This is
confirmed by a new study that has also looked at how cells react when exposed
to more than one kind of nano particle at the same time.
The lead
author of the study is Barbara Korzeniowska from the Department of Biochemistry
and Molecular Biology at SDU. The head of research is Professor Frank Kjeldsen
from the same department.
"Throughout
a lifetime, we are exposed to many different kinds of nano-particles, and we
should investigate how the combination of different nano-particles affects us
and also whether an accumulation through life can harm us," says Barbara
Korzeniowska.
She
herself became interested in the subject when her little daughter one day was
going in the bathtub and got a rubber duck as a toy.
"It
turned out that it had been treated with nano-silver, probably to keep it free
of bacteria, but small children put their toys in their mouths, and she could
thus ingest nano-silver. That is highly worrying when research shows that
nano-silver can damage human cells," she says.
In her new
study, she looked at nano-silver and nano-platinum. She has investigated their
individual effect and whether exposure of both types of nanoparticles results
in a synergy effect in two types of brain cells.
"There
are almost no studies of the synergy effect of nano particles, so it is
important to get started with these studies," she says.
She chose
nano-silver because it is already known to be able to damage cells and
nano-platinum, because nano-platinum is considered to be so-called bio-inert;
i.e. has a minimal interaction with human tissue.
The
nanoparticles were tested on two types of brain cells: astrocytes and
endothelial cells. Astrocytes are supporter cells in the central nervous
system, which i.a. helps to supply the nervous system with nutrients and repair
damage to the brain. Endothelial cells sit on the inside of the blood vessels
and transport substances from the bloodstream to the brain.
When the
endothelial cells were exposed to nano-platinum, nothing happened. When exposed
to nano-silver, their ability to divide deteriorated. When exposed to both
nano-silver and nano-platinum, the effect was amplified, and they died in large
numbers. Furthermore, their defense mechanisms decreased, and they had
difficulty communicating with each other.
"So
even though nano-platinum alone does not do harm, something drastic happens
when they are combined with a different kind of nano-particle," says Frank
Kjeldsen.
The
astrocytes were more hardy and reacted "only" with impaired ability
to divide when exposed to both types of nano-particles.
An earlier
study, conducted by Frank Kjeldsen, has shown a dramatic synergy effect of
silver nanoparticles and cadmium ions, which are found naturally all around us
on Earth.
In that
study, 72 % of the cells died (in this study it was intestinal cells) as they
were exposed to both nano-silver and cadmium ions. When they were only exposed
to nano-silver, 25% died. When exposed to cadmium ions only, 12% died.
"We
are involuntarily exposed—Little is known about how large concentrations of
nano-particles are used in industrial products. We also do not know what size
particles they use—size also has an effect on whether they can enter a
cell," says Barbara Korzeniowska and continues:
"But
we know that a lot of people are involuntarily exposed to nano-particles, and
that there can be lifelong exposure."