Biomedical Engineering Reference
In-Depth Information
well-defined testing conditions. Most important, this requires most complete
characterized nanomaterials with properly chosen sample fractions show-
ing narrowly distributed material properties. The selection of appropriate
reference materials plays a crucial role for many aspects of nanomaterial
research. Their synthesis will therefore remain a demanding task for the
next decade. Establishing nanoscale reference materials goes hand in hand
with progress in nanometrology, which requires reference materials suited
for method calibration.
In addition, reference materials have not only to be well defined with
respect to physical properties, such as primary particle size, surface area,
and porosity; for the determination of doses and size distributions applied
during nanotoxicological testing, detailed knowledge of agglomeration
dynamics in dispersion is needed. This imposes the requirement of well-
defined particle surface chemistry and working concepts for dispersion sta-
bilization. Recently, nanoscaled gold became available as the first certified
reference material for applications in metrology and preclinical biomedical
testing [34].
2.5 Techniques for Nanomaterial Characterization
This section focuses on analytical methods relevant for determination of the
most important material characteristics. It does not provide a complete over-
view of all available techniques.
2.5.1 Minimum Set of Nanomaterial Characteristics
The scientific community aims at identifying correlations between nanomate-
rial properties and biological or ecological responses. For the identification of
the nanomaterial under study and for study comparison purposes, any nano-
toxicological testing therefore requires precise determination of relevant mate-
rial characteristics [35-39]. The characteristics given in Table 2.2 are general
recommendations for a minimum set required for nanotoxicological studies.
The given suggestions may be modified for a particular nanomaterial sample,
if part of the methods are not applicable or do not provide relevant information.
In any case, selecting a set of techniques to characterize a nanomaterial
sample needs to respect the requirements of the scientific community that a
retrospective interpretation of toxicological data in the light of new findings
must be possible [16]. Therefore, all relevant information on all potentially
significant material characteristics must be provided.
For comparable toxicological studies, every processing step used for
preparation of nanomaterial suspensions has to be reported in detail. This
includes additives, dispersion, or sonication setup and applied dispersion
