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Workshop: Safety and Risks in Nanoscience and -technology, February 9th, 2007
Is nano toxic?
Safety and risks in the nanosciences and nanotechnology were the subject of a workshop that was held
by the Swiss Nanoscience Institute (SNI) in Basel on 9 February 2007. Scientists from various Swiss
research institutions presented their latest findings on this subject area. They made it clear that
certain nanomaterials definitely entail risks, but that further research is needed. However, the
nanosciences and nanotechnology also offer enormous opportunities, which also need to be further
researched and applied.
More than a hundred interested participants from science and industry attended the halfday event at
the SNI, University of Basel. Students, assistants and professors were all keen to hear how the
experts assess the safety and risks of different nanomaterials. The SNI had invited scientists from
all over Switzerland to offer their scientific insights into this field. The SNI, too, is set to start
research projects on the safety of nanomaterials in the future. Discussions are currently ongoing as
to which partners may deliver useful results in addition to existing projects.
In summary, it can be said that industrially manufactured nanoparticles and carbon nanotubes are
finding their way into cells and organelles. In various cell culture systems, the nanomaterials
presented show different degrees of toxicity depending on the material tested and the test system.
But scientists today know very little about the longterm consequences of these particles in the cells
of a body. Researchers therefore now need to investigate the mechanisms of the toxicity found, to
submit certain materials to discriminating analysis and to pursue studies over many years. Only
research in interdisciplinary teams will show us which nanomaterials carry a risk potential and how we
can protect ourselves from these risks. At the same time, scientists should not neglect the enormous
opportunities of nanotechnology. including in medicine. As some presentations at this workshop showed,
nanotechnology can serve to keep other risks in check, such as adverse effects of medicines, and to
determine the toxicity of conventional medicines.
Summary of individual presentations:
Prof. Peter Gehr from the University of Berne kicked off the series of lectures. He reported
on the work of his team on a cellular system that simulates the surface of the airways. This acts
like a self-cleaning system of the airway filter upstream of the gas exchange region – the body’s
largest port of entry for nanoparticles. In general, particles that enter the lungs are transported
to the interior of cells to render them harmless. Using the test system presented here, it is now
possible to study the route which the particles take and the way in which the various cell types
(macrophages, dendritic cells, epithelial cells) behave. Larger particles (1 µm) are taken up by
certain cells, the dendritic cells and macrophages, through phagocytosis. This leads to the
formation of a marker substance for inflammation (tumor necrosis factor-α) as a result of
individual particle types. Nanoparticles (0.078 µm) can be detected in macrophages and dendritic
cells. However, they enter the cells by means of a hitherto unknown mechanism. Signs of inflammation
are not observed after uptake. The distribution of inhaled and deposited nanoparticles in the lung is
not a random process. In animal studies, Gehr showed that, 24 hours after exposure, the nanoparticles
were to be found especially in the fine capillaries. Nanoparticles do not only enter the cells of the
lung surface. Gehr also presented studies of red blood cells. These do not take up any microparticles,
but nanoparticles can be detected in the interior of the cell. Within other cells, e.g. in macrophages,
they then also penetrate organelles such as mitochondria, as well as the cell nucleus. However, it is
not yet possible to assess what effect nanoparticles that have penetrated the cells might have on
health. But they might induce oxidative stress in the cells.
Dr. Peter Wick from Empa in St. Gallen was also unable to offer any conclusions on the longterm
effects of nanomaterials. Together with his research group, he is studying the toxicity of carbon
nanotubes (CNTs) in cell culture systems. Carbon nanotubes have a lot of outstanding properties, such
as enormous strength coupled with minimal mass. Amongst other things they are used to make materials
in aeroplane construction lighter and more stable. The production of CNTs is set to multiply in the
next few years, so information on their toxicity is hugely important. Wick’s group has manufactured
CNTs of varying quality from raw materials and tested them with different cell culture systems. The
scientists found that CNTs are absorbed and not broken down by the cells. CNTs in the cells probably
cause oxidative stress and thus exert a toxic effect. Different test systems have shown different
rates of absorption and thus also different cytotoxicity. Wick stressed that it is now important to
study the precise mechanisms underlying these effects.
Prof. Laszlo Forro from the Swiss Federal Institute of Technology (EPF) Lausanne is working
on the toxicity of carbon nanotubes (CNTs) in collaboration with Prof. Schwaller (Histological
Institute Fribourg) and Dr. Pasquier (Cytopath Labor in Geneva). This team is using a colour
reaction to examine how many cells die off as a result of treatment with purified carbon nanotubes.
In his studies the addition of CNTs led to the death of about 50% of cells within the study period
of four days (concentration 0.2 mg/mL). But there were substantial differences between the various
nanotubes: multiwalled nanotubes were less toxic than those with a single wall. The toxicity
increased as a result of surface oxidation. Carbon black has proved especially toxic – this is made
up of tiny soot particles which have been used for many years in car tyres to confer
wear-resistance and good adhesion.
In the lecture by Dr. Martin Kuster, Head of Occupational Health at Novartis, it became clear
how important it is to initiate and complete studies that allow conclusions to be drawn on the
effective impact of nanoparticles throughout the body. He feels that many nanoparticles have to be
classified as problematically for the time being, because they cannot be metabolized by the body.
For him and his work as a doctor, however, it is essential to know the longerterm effects. Only then
can effective precautions be taken.
PD Dr. Patrick Hunziker from the University of Basel steered the interest of the audience in a
different direction. He illustrated how nanoproducts and nanotechnology may be able to solve some
fundamental problems in medicine. As a practising physician in an intensive care unit, he is witness
every day to the fact that diseases such as arteriosclerosis, which leads to myocardial infarction and
stroke, start at the cellular level. But he does not have sufficiently refined instruments and
treatment methods at his disposal to engage in optimally effective diagnosis and treatment that is both
low in side effects and low on costs before the disease actually develops. Carriers of medicines in
nanoscale dimensions now promise more targeted use of medicines for the treatment of diseased cells and
organs. However, unlike the nanoparticles mentioned above, these carriers are not solid objects, but
act as “envelopes” in which a suitable active ingredient can be packed and conveyed specifically to the
focus of disease. Ongoing experiments show that the dose of medication needed and any side effects can
be reduced using this method. In support of these efficacy studies, the scientists place great value on
better understanding the interplay between such medicine carriers and living cells and organisms and
thus identifying toxicity problems at the earliest stage. On this subject, Hunziker pointed to some
experiments that have so far yielded highly promising results.
Dr. Christof Fattinger from Discovery Enabling Sciences at Hoffmann-La Roche, also focused
rather on the opportunities than the risks of nanotechnology. He demonstrated how toxic effects can
be studied using nanotechnology. Together with the IBM Research Laboratory in Rüschlikon, his team
has developed a test system that allows a large number of parameters to be tested simultaneously in
the tiniest blood, serum or tissue samples. This system, for example, enables the concentration of
tumor necrosis factor-α to be measured, as a result of which conclusions can be drawn on
inflammatory processes in the body. Pointers to disease processes or potential toxic side effects
of medicines can thus be obtained at an early stage and with far fewer animal experiments.
Nanoanalytical methods based on “gene chips” are already being used today in human diagnostics in
order to adjust the treatment of certain diseases immediately and precisely to the needs of the
patient and thus also to avoid unwanted side effects.
The Swiss Nanoscience Institute (SNI)
The Swiss Nanoscience Institute (SNI) developed from the National Center of Competence in
Research (NCCR) “Nanoscale Science” and constitutes a priority program of the University of Basel.
It combines basic science with application-orientated research. In various projects researchers
focus on nanoscale structures and aim at providing new impact and ideas to the life sciences, to
the sustainable use of resources, and to information and communication technologies. The University
of Basel as the leading house coordinates the NCCR network of universities, federal research
institutes, and industrial partners, which is a research instrument of the Swiss National Science
Foundation, and the Argovia-network, which is financed by the Swiss Canton of Aargau. With the
establishment of the SNI the University of Basel continues to secure the internationally
acknowledged position as a centre of excellence in nanoscale sciences.
Contact:
Prof. Christian Schönenberger, University of Basel
Tel: + 41 (0)61 267 36 90
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