General overview »
Magnetic Nanoparticles »
Standardization »
Characterization and
analysis methods »
DC magnetization and AC
susceptometer analysis »
Medium and high frequency
AC susceptometry »
Mössbauer spectroscopy »
Electron microscopy »
XRD and SAXS »
SANS »
Electron microscopy »
Ferromagnetic resonance »
Dynamic light scattering and
electrophoretic light scattering »
Field-flow fractionation »
Magnetic modelling »
Magnetorelaxometry »
Magnetic particle spectroscopy »
Magnetic particle rotation »
Magnetic separation »
NMR R1 and R2 relaxivities »
Magnetic nanoparticle bio-detection »
Magnetic hyperthermia measurements »
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Standardization
Despite a large research effort and significant progress in the biomedical application of MNP, the critical metrological foundations do not exist, due to the intrinsic difficulty, lack of adequate equipment and high cost of accurate and reproducible characterization. Very few regulations on the use of MNPs and related equipment for clinical application procedures do exist. Even for the established applications of MNPs in routine diagnostic procedures like MRI, there is the urgent need for traceable measurement techniques that characterize the quality of the MNPs. The consequences of this lack of metrology and regulations are late diagnostics and severe side effects, which currently have a significant impact on patient’s quality of life and often decrease survival prognoses. The Co-Nanomet (Co-ordination of Nanometrology in Europe) initiative of the EC recommended a general strategy for implementation of standards in the fields of nanotechnology, addressing the following items:
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Define the relevant measurands
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Describe the available measurement techniques with respect to their limits and fields of application
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Develop and summarize concepts for traceability and determination of measurement uncertainy in the relevant analysis techniques for the relevant measurands -Summarize existing standards and start development of new standards for measurement of relevant physical properties
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Provide reference materials for other groups
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Reveal current and future needs of metrology for magnetic nanoparticles.
While recent nanometrology initiatives focused on geometrical or morphological properties of nanoparticles, it is clear that for magnetic nanoparticles functional properties related to their magnetism are of outstanding importance. The measurement of the distribution of magnetic moments, anisotropy energies and cooperative static and dynamic magnetization behavior in MNP ensembles and the relation of these parameters to MNP geometry and to the hydrodynamic environment has to be traced back to existing primary standards. For selected methods, the complete expression of uncertainties according to the internationally accepted GUM (Guide to the Expression of Uncertainty in Measurement, ISO/IEC Guide 98-3:2008—Part 3) has to be demonstrated.
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