Gold Nanoparticle Uptake in Tumor Cells: Quantification and Size Distribution by sp-ICPMS

Gold nanoparticles (AuNPs) are increasingly studied for cancer treatment purposes, as they can potentially improve both control and efficiency of the treatment. Intensive research is conducted in vitro on rodent and human cell lines to objectify the gain of combining AuNPs with cancer treatment and to understand their mechanisms of action. However, using nanoparticles in such studies requires thorough knowledge of their cellular uptake. In this study, we optimized single particle ICPMS (sp-ICPMS) analysis to qualify and quantify intracellular AuNP content after exposure of in vitro human breast cancer cell lines. To this aim, cells were treated with an alkaline digestion method with 5% TMAH, allowing the detection of gold with a yield of 97% on average. Results showed that under our experimental conditions, the AuNP size distribution appeared to be unchanged after internalization and that the uptake of particles depended on the cell line and on the exposure duration. Finally, the comparison of the particle numbers per cell with the estimates based on the gold masses showed excellent agreement, confirming the validity of the sp-ICPMS particle measurements in such complex samples

Determination of Boron Concentration in Geochemical Reference Materials Extracted by Pyrohydrolysis and Measured by ICP-MS

International audienceThis article presents new boron concentrations for nine geochemical reference materials (GS-N, FK-N, GL-O, BX-N, DT-N, AN-G, GH, Mica-Fe, Mica-Mg). After extraction by a modified pyrohydrolysis technique, boron concentrations were measured by ICP-MS. The blank levels for the whole procedure were 0.091 +/- 0.020 ng ml(-1) or 14 +/- 5 ng of boron in total. The method was first validated by measuring nine reference materials with known boron concentrations. The determined boron concentrations are all within the range of recommended or published values, which means that the yields were 100%, and show precisions below 10% for samples containing over 2 mu g g(-1) of boron

Characterization of boron incorporation and speciation in calcite and aragonite from co-precipitation experiments under controlled pH, temperature and precipitation rate

International audienceAbout 20 years ago, the boron isotopic composition of marine carbonates was proposed as a proxy of ancient seawater pH. Since that time, a large body of studies has used boron isotopes in carbonates to reconstruct seawater paleo-pH and atmospheric paleo-CO2 concentration. To date, however, no systematic investigation of the physicochemical parameters that control boron incorporation in calcite and aragonite (pH, temperature, precipitation rate, etc.) has been performed. To fill this gap, we have experimentally investigated the inorganic co-precipitation of boron with calcite and aragonite at 5 and 25 °C in the presence and absence of seed crystals and over the pHNBS range 7.4 B, between CaCO3 and the fluid is defined as

A fully automated direct injection nebulizer (d-DIHEN) for MC-ICP-MS isotope analysis: application to boron isotope ratio measurements

International audienceThis work presents a fully automated setup for using direct injection nebulization as an introduction system for solution measurements by MC-ICP-MS, here applied to boron isotopes in pure boric acid solutions and natural samples. In this setup, a direct injection nebulizer (d-DIHEN) is plugged into the plasma torch without any spray chamber, and an automated 6-port valve interfaces the nebulizer and the autosampler. The advantages of a d-DIHEN for boron isotope ratio measurements are high sensitivity and short washout times, allowing for sample-standard bracketing (SSB) measurements at a higher rate than spray chambers. The measurement of boron isotopes by MC-ICP-MS at an unprecedented sub 0.1 parts per thousand, repeatability level (2 standard deviation = 2SD) was achieved for pure boric acid solutions. The improved precision is allowed by a better stability of the introduction system with continuous operation of the peristaltic pump (which was manually switched off between samples before automation) and due to the possibility of multiple analyses of the same sample solution. However, such a good repeatability was not systematically obtained for boron isotopes SSB measurements of natural samples (in fine 2SD are between 0.02 and 0.5 parts per thousand). Boron from natural samples has to be extracted before isotope analysis, with one to four steps depending on the sample type. Repeated analyses of boron independently separated up to ten times from the same sample lead to an external reproducibility no better than 0.2 parts per thousand. Boron chemical separation from the samples prior to MC-ICP-MS analyses seems to remain the main limitation to precise measurements of boron isotope ratios

Developing boron isotopes to elucidate shale weathering in the critical zone

To further develop boron isotopes as a tool for understanding shale weathering, we explored patterns of boron concentrations and isotopes across the forested Susquehanna Shale Hills Critical Zone Observatory (CZO). We present boron measurements for all watershed components that provided a foundation for examining water-rock interactions in a shale dominated watershed, including water compartments (e.g., precipitation, stream water, groundwater) and solid compartments (e.g., soil, bedrock, stream sediments, suspended load, and leaf litter). Results show boron isotopes (δ11B) in the bedrock (− 4.6‰) and soil (− 5.9 to - 4.2‰) were very similar. All waters were enriched in 11B by comparison: precipitation (7.2 to 22.6‰), stream (10.3 to 15.5‰), and groundwater (2.2 to 17.4‰). Modeling revealed that isotopic fractionation observed in the surface water and groundwater could mainly be explained by water-rock interactions including clay mineral dissolution (e.g., chlorite) and coprecipitation/adsorption processes (e.g., coatings on illite particles), likely in the near surface soils (~2 m deep). We found that leaching, the loss of boron from vegetation to stream water, plays a secondary role. Specifically, such leaching likely contributes the equivalent of 10 to 26% of the B fluxes from the watershed outlet. Boron mass balance between bedrock and precipitation inputs and the exported flux of dissolved and solid pools identified a “missing” isotopically light solid flux (δ11B of −12.2 ± 5.3‰ at ~4.4 ± 3.8 mol/ha/y of B; uncertainty reported as 2 SD). We did not sample any pool with this isotopic signature. Here our data suggest the composition of this pool is more likely related to precipitation of secondary clays rather than adsorption or (co)precipitation on Fe oxides. We propose two hypotheses to explain the missing light B pool: 1) a significant portion of the particles carrying the missing 10B are not sampled because they enter groundwater at depth and are transported out of the catchment under the stream; and/or 2) the inputs and outputs of boron are not operating at steady state in the catchment today, suggesting that the missing boron particles were lost in the past in proportions higher than today. When this B budget is paired with studies of δ26Mg and δ56Fe from Shale Hills, both of which also show missing isotopic pools, the pattern indicates a fundamental gap in understanding of shale weathering. We concluded that light B particles, presumably generated in the upper soils, are likely transported deep beneath the surface in the groundwater system or episodically in the past through riverine fluxes

Mice exposed to food-grade TiO 2 from in utero life to adulthood show sex-specific gut microbiota and metabolic disorders

International audienceThe use of titanium dioxide (TiO 2) particles as a food additive (E171 in EU) in ultra-processed foods raises public health issues. Our previous study showed transplacental passage of TiO 2 nanoparticles in the human placenta, and presence of TiO 2 particles in meconium, demonstrating foetal exposure. Due to biocidal properties of TiO 2 , whether E171 exposure starting early during pregnancy may alter the establishment of gut microbiota homeostasis with potential deleterious effects at adulthood has not been explored. The current study in mice aimed to assess the perinatal fate of E171 given to dams and the consequences on gut microbiota and metabolic functions of the offspring. Female mice were exposed to a control or E171-enriched diet at a human relevant level (10 mg/kg bw/day) during pregnancy and lactation until weaning of pups, then the descendants were fed with the same diet as their mother until postnatal day (PND) 150. Oral glucose tolerance and fasting insulin were assessed at PND143. At PND150, all mice were sacrificed and gut microbiota composition as well as intestinal pro-and anti-inflammatory cytokine production were measured by 16S gene sequencing and ELISA, respectively. Biodistribution of TiO 2 particles was also studied by ICP-MS in fetus at day 18 of pregnancy, and in the liver at PND150. In E171-exposed mice, higher Ti level was first detected in fetus, and Ti accumulation was reported in liver at PND150 compared to controls regardless of the sex. Changes in gut microbiota composition occurred in E171-exposed male only, showing increased βdiversity and of the Firmicutes/Bacteroidetes ratio. Increased production of the pro-inflammatory cytokine IL1β in the colon as well as glucose intolerance and higher fasting insulin levels were also reported in E171-exposed male relative to controls. In contrast, decreased secretion of pro-(IL1β, TNFα, IFNγ, IL17) and anti-(IL10) inflammatory cytokines occurred in the colon of E171-exposed females, without other changes. These results showed that long term exposure to E171 from in utero life alters intestinal and metabolic homeostasis in a sex-dependent manner, characterized by altered glucose metabolism and gut dysbiosis in male mice only