Biomedical Engineering Reference
In-Depth Information
that the toxicity of ZnO NPs is independent of the amount of soluble Zn ions in the cell culture
media [10]. At present, researchers have not been able to establish a single physicochemical param-
eter, for instance, size, shape, surface [7], chemical composition [8], ion [9], or conduction [3],
which best describes the toxicity of NMs. Instead, a variety of physicochemical parameters have
been suggested to contribute to the biological behaviors of NMs. Thus, a full characterization of
NMs [11] is essential in order to correlate the physicochemical parameters with toxicity, and the
identification of the main physicochemical factors that govern the toxic effects of NMs is impor-
tant for the safe design and synthesis of NMs. This also allows researchers to establish predictive
paradigms for the potential risks of NMs [3,12]. Knowledge about the interactions of NMs with
biological surroundings is still in its infancy. This constitutes the key challenge and issue when
assessing the toxicity of NMs.
In the field of materials science, the characterization methods for NM properties are well devel-
oped and established, including the use of advanced scanning probe microscopy [13-15] and electron
microscopy [1,3,16,17]. For nanotoxicity studies, there are suggestions for the minimum analytical
characterization of NMs for hazard assessments in biological matrices, including size distribution,
shape, chemical composition, surface properties, agglomeration/aggregation, and solubility [11].
Different protocols for dispersing the same type of NM, for example, ultrasonication, shaking, and
vortexing, or various solvents, will lead to various states (charge, agglomeration, aggregation, or
dissolution) in a suspension. This suggests that performing characterizations in biological envi-
ronments is of more importance than the measurement of primary NMs for hazard evaluations.
Therefore, most of the current techniques become less powerful for measurements when NMs are in
biological environments due to the dynamical interaction of the NMs with their surrounding matrix
[1,2,18]. Because most of the toxic analyses of NMs have been on the basis of the primary charac-
teristics of NMs measured prior to the dispersion of NMs in biological matrices, it is not surprising
that there are controversial conclusions for the same type NM and the same cell lines regarding
toxic effects and their correlation with physiochemical parameters.
8.2
CHARACTERIZATION OF PRIMARY NMs IN DRY STATE
8.2.1 t
erMINology
aNd
d
efINItIoNs
for
NM
s
Many terms and labels have been used with the prefix “nano” in practice, as well as in science
and engineering. This causes misunderstandings in the real meaning of such terms. However, no
internationally harmonized definition of “nanomaterial” exists yet, even though a wide range of
definitions have indeed been discussed and proposed [19]. Therefore, it is very important to estab-
lish precise and unambiguous definitions that can explain the NMs as part of standardization for
nanotoxicology. We propose a nomenclature for NMs collected from the existing literature.
The term “material” is often used intuitively without a legislative definition. According to
Lovestam et al. [19], the term “material” refers to a single or closely bound ensemble of substances,
at least one of which is in a condensed phase, where the constituents of the substance are atoms and
molecules. The term “condensed phase” is generally used in thermodynamics for phases where a
strong interaction between the constituents (i.e., atoms and molecules) exists; therefore, either the
solid or liquid phases of a substance.
The ISO/TS 80004 series of standards, from the International Organization for Standardization
(ISO) [20,21], describe vocabulary for nanotechnology and its applications. These were largely
motivated by health, safety, and environment concerns of nanotechnology.
• ISO/TS 80004-1:2010 Nanotechnologies—Vocabulary—Part 1: Core terms. This docu-
ment lists a number of core terms relevant to nanoscale materials, several of which are
related to NMs, such as nanoscale, NM, nano-object, nanostructure, nanostructured mate-
rial, manufactured NM, engineered NM, nanoscale phenomenon, and nanoscale property.
