Timing, hosts and locations of (grouped) events of NanoImpactNet

NanoSafetyCluster - Compendium 2012
characterization is being carried out, such as ICP-MS and TGA for a
more complete analysis.
To evaluate the migration of nanomaterial from the polymeric
matrices, nanocomposites will be analyzed by TEM and SEM and
compare with those before ageing. These results will be
complemented with the data obtained for the nanomaterial
recovered from the simulated rain during aging. Furthermore,
analysis by ICP-MS is in progress to allow nanomaterial
quantification in the nanocomposite after ageing. Degradation of
the polymer is being determined by analytical characterization
with TGA and DSC.
For comparison, it was designed an additional experiment
outdoors with the nanocomposites samples. In this case, 5
specimens of each nanocomposite are being exposed to external
conditions for a total exposure time of 1 year. Data obtained will be
used to determine the equivalence of the accelerated aging in the
weathering chamber with a real ageing process in a Mediterranean
climate.
3.4 Development of non-destructive separation
techniques: Proof of concept of NM recycling and
disposal techniques
The main objective of this WP is the development of techniques for
the separation of nanofillers from polymeric matrix without
inducing degradation of the nanomaterials under the form
encountered in the composites. Therefore firstly, research was
conducted in the methodologies to dissolve the polymers without
affecting the physico-chemical properties of the nanomaterials.
From the different methodologies found, were selected those
ones with the mildest conditions and then tested with raw
nanomaterials. The results indicated that the most affected
nanomaterials were the metal oxide nanoparticles changing their
surface chemistry or their degree of functionalization. Even
though, these results cannot be totally extrapolated to the effects
on the nanofillers of the nanocomposites, because the polymeric
matrix can protect the nanomaterial.
These methodologies are applied to the polymeric
nanocomposites and the colloidal solution obtained will be then
filtered to separate the nanomaterials from the polymeric
matrices. Centrifugation and membrane nanofiltration are being
optimized for the filtration of those colloidal solutions that are
dissolved at room temperature. On the other hand, ceramic
nanofiber filters have been developed by means of electrospinning
technique and characterized for their morphology and separation
efficiency. Optimization of these ceramic nanofiber filters is in
progress for the filtration of the colloidal solutions at high
temperature.
The nanomaterials collected after all the different filtration processes
will be fully characterized and their toxicological profile will be
determined.
Free standing TiO 2 nanofiber mat
TiO 2 nanofibers
3.5 Toxicological and ecotoxicological evaluation of
NM at different stages of their life cycle
The starting point of the toxicological studies was the dispersion of
nanomaterials in an aqueous solution. The raw nanomaterials
studied in Nanopolytox project have diverse chemical
compositions and surface properties making more difficult the
selection of the adequate dispersant. The dispersion studies have
been carried out case by case and the dispersion protocols have
been described for each nanomaterial. The dispersants selected
for the studies were Bovine Serum Albumin (BSA), Fetal Bovine
Serum (FBS), Tween 20, Sodium Citrate and MilliQ H 2O. The control
over the stability of nanomaterials in the dispersion medium was
studied with different analytical techniques: UV-vis spectroscopy,
ζ-potential analysis and DLS. The data collected was analyzed and
the best dispersion medium was selected for each nanomaterial.
The toxicity of raw nanomaterials has been evaluated in a battery
of human cell lines and in a fish embryo test and the toxicity
evaluation of the aged nanomaterials is now ongoing. A series of
mechanistic assays, such as apoptosis induction, cell proliferation
and cell internalization, have also been performed. The results
showed considerable differences in toxic potential and
mechanisms of toxicity among the nanomaterials of the project,
but relatively good correspondence between the toxic potential in
fish embryos and in human cell lines. In both test systems,
nanoclays were the most toxic nanomaterials, and their toxicity
seemed to be associated to the organic modifiers used in their
functionalization. The toxic potential of zinc oxide nanoparticles
was higher in human cell lines than in the standard parameters of
the fish embryo test, although they did affect embryo hatching.
This suggests that zinc nanoparticles may not able to cross the yolk
sac.
Several ongoing studies are further investigating the toxicity and
the environmental fate of the nanomaterials. These studies
include in vitro and in vivo ADME studies, terrestrial toxicity,
bioaccumulation in fish, and adsorption-desorption studies.
164 Compendium of Projects in the European NanoSafety Cluster