Civil Engineering Reference
In-Depth Information
Table 7.3
Overview characterization of ENMs. While Class 1 properties are
intrinsic to a nanomaterial itself, the Class 2 properties are dependent on the
interplay between ENM and assay system
Nanomaterial property
Available analytical techniques
Class 1: 'As produced' - morphology and structure
Primary particle size, shape, and size
distribution
TEM, SEM, AFM, ESEM, FIB-SEM,
cryo-TEM
Fractal structure
TEM, SAXS, SANS
Pore size, porosity, and surface area
BET, SAXS, SANS
Crystallinity, framework structure,
and crystal size
XRD, Raman, SAXS, NMR
Chemical composition
Raman, NMR, EDAX, FTIR, XPS, ICP
Elemental speciation and redox state
Raman, XAFS, XANES, NMR
Electronic, magnetic, and photonic
properties
SAXS, Mossbauer, ESR, Raman,
UV-Vis
'Dustiness' or tendency to aerosolize EMPS, SMPS
Class 2: 'As dispersed' - interfacial properties
Dispersed size and size distribution
DLS, EMPS, SMPS, laser diffraction
Aggregate size
DLS, electroacoustics
Charge density, pKa, PZC, ionization
fraction
Direct titration in various
suspending media
Surface (zeta) potential and IEP
EPM measurements in various
suspending media
Surface tension components (LW,
g
Multiple probe liquid contact angle/
tensiometry
+
, g
−
)
Roughness and chemical
heterogeneity
AFM, CFM, FTIR, XPS, NMR, Raman
as these important parameters are dependent on the media matrix they
are in.
For example, ions play an important role for the aggregation behaviour
of MNMs (Jin
et al.
, 2010). Moreover, the MNM dispersions are typically
not stable and much effort has been put into the discovery of suitable dis-
persal agents, which are compatible with the biological system in which they
are to be tested. In this context it has to be mentioned that dispersion agents
used for the stabilization during testing of MNMs do modify the surface of
the material and may therefore interfere in toxicity screening: for example,
DPPC in relatively high doses has been shown to completely suppress the
cytotoxicity and pro-apoptotic effects of quartz nanoparticles (Gao
et al.
,
2001). In this context it should be noted that, although nanoparticle disper-
sion has been extensively researched, only a few studies have addressed the
stability of the resulting dispersions and only limited information is avail-
able from systematic studies on the effect of proteins and other chemical
surfactants on nanoparticle stability in assay media such as cell culture
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