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- Silica nanoparticles (3) (entfernen)
Organisationseinheit der BAM
Cell cultures form the basis of most biological assays conducted to assess the cytotoxicity of nanomaterials.
Since the molecular environment of nanoparticles exerts influence on their physicochemical properties, it can have an impact on nanotoxicity. Here, toxicity of silica nanoparticles upon delivery by fluid-phase uptake is studied in a 3T3 fibroblast cell line. Based on XTT viability assay, cytotoxicity is shown to be a function of (1) particle concentration and (2) of fetal calf serum (FCS) content in the cell culture medium.
Application of dynamic light scattering shows that both parameters affect particle agglomeration. The DLS Experiments verify the stability of the nanoparticles in culture medium without FCS over a wide range of particle concentrations.
The related toxicity can be mainly accounted for by single silica nanoparticles and small agglomerates. In contrast, agglomeration of silica nanoparticles in all FCS-containing media is observed, resulting in a decrease of the associated toxicity. This result has implications for the evaluation of the cytotoxic potential of silica nanoparticles and possibly also other nanomaterials in standard cell culture.
An inter-laboratory comparison on the particle size, expressed as mean diameter d, of nanoscaled SiO2 (#14 BAM Silica (see NanoValid DoW, D.5.41/5.42)) has been performed. The majority of participants used Dynamic Light Scattering (DLS). A few used Electron Microscopy as method. Following methods had been applied by only one partner, respectively: Small Angle X-ray Scattering, Analytical Ultracentrifugation, Atomic Force Microscopy and Atomizer with electric mobility spectrometer.
An inter-laboratory comparison on the surface charge, expressed as zeta potential ζ, of nanoscaled SiO2 has been performed using #14 BAM Silica (see D.5.41/5.42) nanoparticles. The comparability of results delivered by participants has been tested.
The Task 5.4 of NanoValid is designed to test, compare and validate current methods to measure and characterize physicochemical properties of selected engineered nanoparticles. The measurand is Surface charge expressed as zeta-Potential. The measurements are to be accompanied by estimates of the uncertainties at a confidence level of 95%, deduced from the standard uncertainties. Therefore an uncertainty budget comprising statistical (Type A) and systematic (Type B) errors has to be established and delivered for the measurand. The protocol comprises two Annexes addressing the establishment of uncertainty budgets following GUM. The final goal of the comparison is to identify those methods of measurement which have potential as reference methods in pc characterization of nanoparticles for the determination of a given measurand.