Chemische Charakterisierung und Spurenanalytik
Filtern
Erscheinungsjahr
- 2018 (13) (entfernen)
Dokumenttyp
- Zeitschriftenartikel (13) (entfernen)
Sprache
- Englisch (13)
Referierte Publikation
- ja (13) (entfernen)
Schlagworte
- Laser ablation (3)
- ICP-MS (2)
- LA-ICP-MS (2)
- Nanoparticle (2)
- Traceability (2)
- Absorption spectrometry (1)
- Affinity chromatography (1)
- Affinity extraction (1)
- Arsenite (1)
- Atomic Force Microscopy (1)
Organisationseinheit der BAM
Iron nanoparticles (NPs) metabolism is directly associated to human health due to their use as anemia treatment and should be studied in detail in cells. Here we present a speciation strategy for the determination of the metabolic products of iron oxide nanoparticles coated by tartaric and adipic acids in enterocytes-like cell models (Caco-2 and HT-29). Such methodology is based on the use of SDS-modified reversed phase high performance liquid chromatography (HPLC) separation using inductively coupled plasma-mass spectrometry (ICP-MS) as Fe selective detector. Post-column isotope dilution analysis is used as quantification tool by adding Fe-57 as isotopically enriched standard. To assess the separation capability of the method, two different iron nanostructures: iron sucrose nanoparticles -Venofer®- used as model suspension and iron tartrate/adipate-modified nanoparticles, both of about 4 nm (core size) were evaluated. The two nanostructures were injected into the system showing good peak profiles and quantitative elution recoveries (>80%) in both cases. In addition, both nanoparticulate fractions could be based-line separated from ionic iron species, which needed to be complexed with 1mM citrate to elute from the column. Exposed cells up to 0.5mM of iron tartrate/adipate-modified nanoparticles were specifically treated to extract the internalized NPs and the extracts examined using the proposed strategy. The obtained results revealed the presence of three different fractions corresponding to nanoparticle aggregates, dispersed nanoparticles and soluble iron respectively in a single chromatographic run. Quantitative experiments (column recoveries ranging from 60 to 80%) revealed the presence of the majority of the Fe in the nanoparticulated form (>75%) by summing up the dispersed and aggregate particles. Such experiments point out the high uptake and low solubilization rate of the tartrate/adipate NPs making these structures highly suitable as Fe supplements in oral anemia treatments.
The impact of nanoparticles, NPs, at the single cell level has become a major field of toxicological research and different analytical methodologies are being investigated to obtain biological and toxicological information to better understand the mechanisms of cell–NP interactions. Here, inductively coupled plasma mass spectrometry in the single cell measurement mode (SC-ICP-MS) is proposed to study the uptake of silver NPs, AgNPs, with a diameter of 50 nm by human THP-1 monocytes in a proof-ofprinciple experiment. The main operating parameters of SC-ICP-MS have been optimized and applied for subsequent quantitative analysis of AgNPs to determine the number of particles in individual cells using AgNP suspensions for calibration. THP-1 cells were incubated with AgNP suspensions with concentrations of 0.1 and 1 µg/mL for 4 and 24 hours. The results reveal that the AgNP uptake by THP-1 monocytes is minimal at the lower dose of 0.1 µg/mL (roughly 1 AgNP per cell was determined), whereas a large cell-to-cell variance dependent on the exposure time is observed for a 10 times higher concentration (roughly 7 AgNPs per cell). The method was further applied to monitor the AgNP uptake by THP-1 cells differentiated macrophages incubated at the same AgNP concentration levels and exposure times demonstrating a much higher AgNP uptake (roughly from 9 to 45 AgNPs per cell) that was dependent on exposure concentration and remained constant over time. The results have been compared and validated by sample digestion followed by ICP-MS analysis as well as with other alternative promising techniques providing single cell analysis.
The mechanism of action of zirconium permanent modifiers on graphite surfaces was investigated in order to understand its influence on the analytical signal in atomic and molecular absorption spectrometry (AAS/MAS). For this, the molecule formation of CaF was studied, which is used for the indirect analytical determination of fluorine in high-resolution continuum source graphite furnace molecular absorption spectrometry (HR-CS-GFMAS). The kinetics of this reaction was established by monitoring its molecular spectrum at different atomisation temperatures. An Arrhenius plot showed a pseudo-first order reaction with respect to fluorine (n = 1). An intermediate state was isolated, and its structure was elucidated by spectroscopic methods: scanning electron microscopy with energy dispersive X-ray spectroscopy (SEMEDX), X-ray photoelectron spectroscopy (XPS), X-ray absorption spectroscopy (XANES and EXAFS), and Raman microspectroscopy. We propose here a mechanism, where ZrO2 acts as a heterogeneous catalyst: after a pyrolytic step, an intermediate state of ZrO(OCaF) is activated, and at higher temperatures, CaF(g) is released from the zirconium-coated graphite surface. No evidence of the formation of zirconium carbide was found. Consequently, as the CaF formation is catalysed by a heterogeneous catalyst, surface modifications with ZrO2 nanoparticles and ZrO xerogels were investigated in order to increase the surface area. Their influence was evaluated in the molecule formation of CaF, CaCl, CaBr, and CaI. Graphite furnace modification with zirconium oxide nanoparticles proves to be the best choice for fluorine analysis with a signal enhancement of more than eleven times with respect a non-coated graphite furnace. However, the influence of zirconium modifications in the analytical signals of Cl, and I is lower than the F signals or even negative in case of the Br. Understanding zirconium modifiers as heterogeneous catalysts offers a new perspective to AAS and MAS, and reveals the potential of surface analytical methods for development of improved permanent modifiers and graphite furnace coatings.