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The CCQM-K148.a comparison was coordinated by the BIPM on behalf of the CCQM Organic Analysis Working Group for NMIs and DIs which provide measurement services in organic analysis under the CIPM MRA. It was undertaken as a "Track A" comparison within the OAWG strategic plan. CCQM-K148.a demonstrates capabilities for assigning the mass fraction content of a solid organic compound having moderate molecular complexity, where the compound has a molar mass in the range (75 - 500) g/mol and is non-polar (pKow < −2), when present as the primary organic component in a neat organic solid and where the mass fraction content of the primary component in the material is in excess of 950 mg/g.
Participants were required to report the mass fraction of Bisphenol A present in one supplied unit of the comparison material. Participants using a mass balance method for the assignment were also required to report their assignments of the impurity components present in the material. Methods used by the seventeen participating NMIs or DIs were predominantly based on either stand-alone mass balance (summation of impurities) or qNMR approaches, or the combination of data obtained using both methods. The results obtained using thermal methods based on freezing-point depression methods were also reported by a limited number of participants. There was excellent agreement between assignments obtained using all three approaches to assign the BPA content.
The assignment of the values for the mass fraction content of BPA consistent with the KCRV was achieved by most of the comparison participants with an associated relative standard uncertainty in the assigned value in the range (0.1 - 0.5)%.
Uptake and molecular impact of aluminum-containing nanomaterials on human intestinal caco-2 cells
(2018)
Aluminum (Al) is one of the most common elements in the earth crust and increasingly used in food, consumer products and packaging. Its hazard potential for humans is still not completely understood. Besides the metallic form, Al also exists as mineral, including the insoluble oxide, and in soluble ionic forms. Representatives of these three species, namely a metallic and an oxidic species of Al-containing nanoparticles and soluble aluminum chloride, were applied to human intestinal cell lines as models for the intestinal barrier. We characterized physicochemical particle parameters, protein corona composition, ion release and cellular uptake. Different in vitro assays were performed to determine potential effects and molecular modes of Action related to the individual chemical species. For a deeper insight into signaling processes, microarray transcriptome analyses followed by bioinformatic data analysis were employed. The particulate Al species showed different solubility in biological media. Metallic Al nanoparticles released more ions than Al2O3 nanoparticles, while AlCl3 showed a mixture of dissolved and agglomerated particulate entities in biological media. The protein corona composition differed between both nanoparticle species. Cellular uptake, investigated in transwell experiments, occurred predominantly in particulate form, whereas ionic Al was not taken up by intestinal cell lines. Transcellular transport was not observed. None of the Al species showed cytotoxic effects up to 200 mg Al/mL. The transcriptome analysis indicated mainly effects on oxidative stress pathways, xenobiotic metabolism and metal homeostasis. We have shown for the first time that intestinal cellular uptake of Al occurs preferably in the particle form, while toxicological effects appear to be ion-related.
Plasma functionalisation in gas phase like ammonia allows to equip polymer surfaces with amino functional groups. An important question of this functionalisation consists in the limited knowledge about heterogeneous interface reactions, especially radical formation and subsequent reaction processes. Useful analytical methods comparable to those avilable for gas phase reactions are scarce. Here we report on investigations on plasma generated C-radicals by NO-labelling, showing similatr effects for different plasmas.
Pulsed and cw microwave plasma excitation for surface functionalization in nitrogen-containing gases
(2003)
Results are presented of polymer surface functionalization processes in pulsed and continuous wave (cw) microwave-excited plasmas in nitrogen-containing gases under admixture of hydrogen. A maximum selectivity of 100% for amino groups with respect to all nitrogen functional groups (NH2/N) was obtained in cw microwave (MW) plasmas either for very short treatment durations below 100 µs in pure NH3, or within approximately 10 s in hydrogen-rich nitrogen-containing plasmas. The amino and overall nitrogen surface densities, NH2/C and N/C, reach up to 3.5% and 35%, respectively. Post plasma processes of functionalized polymers are discussed in the light of monofunctionalization. Down to pulse duration of 1 ms, plasma decomposition rates of NH3, determined by infrared absorption spectroscopy, are found to scale linearly with the duty cycle. In this regime, the main effect of a duty cycle variation in pulsed NH3 plasmas on surface functionalization can be interpreted to result from changes in the concentration of the dominant stable species in the gas phase, NH3, N2 and H2, which are activated by subsequent plasma pulses. With increasing duty cycle, NH3 decomposition to N2 and 3H2 more and more dominates over the supply of fresh NH3. The nitrogen-removing role of hydrogen in the plasma is discussed in detail, whereas the role of the numerous transient nitrogen-containing species remains to be studied in the future.
Low-pressure gas-discharge plasmas are widely used for polymer surface functionalization on industrial scale. For biomaterial applications, the density and selectivity of the functionalization are of particular importance, because functional groups control the immobilization of biomolecules. Therefore, surface modification of biomaterials is a challenging task for low-pressure plasma technique. Plasma processes have been successfully applied to various polymer types in order to generate multifunctional surfaces. This paper discusses the present state and the prospects of non-coating plasma processes to generate mono functional surfaces of controlled amino group density. Such surfaces appear most desirable for many applications. The results of various microwave- and radio-frequency- excited plasma processes reported in the literature are reviewed and compared to a sequence of experiments that was conducted in a UHV reaction environment. Non-thermal plasmas are especially well suited for thermally damageable polymers. The effect of hydrogen admixture to discharges in nitrogen and ammonia is discussed in detail. The optimization of process parameters lead to highly selective amino functionalization of high density. The selectivity reached 100% -NH2/N at a surface density of amino groups of 3% -NH2/C.
The use of biodegradable bone substitutes is advantageous for alveolar ridge augmentation because it avoids second-site surgery for autograft harvesting. This study examines the effect of novel, rapidly resorbable calcium phosphates and a calcium phosphate bone cement on the expression of bone-related genes and proteins by human bone-derived cells (HBDCs) and compares this behavior to that of tricalciumphosphate (TCP). Test materials were -TCP, two materials with a crystalline phase Ca2KNa(PO4)2 and with a small amorphous portion containing either magnesium potassium phosphate (material denominated GB14) or silica phosphate (material denominated GB9), and a calcium phosphate bone cement (material denominated Biocement D). HBDCs were grown on the substrata for 3, 7, 14, and 21 days, counted, and probed for various mRNAs and proteins (type I collagen, osteocalcin, osteopontin, osteonectin, alkaline phosphatase, and bone sialoprotein). All substrates supported continuous cellular growth for 21 days. In the presence of GB14 and Biocement D specimens cell proliferation was reduced and cell differentiation increased. At day 21, the greatest number of cells was found on GB9 expressing significantly higher levels of bone-related proteins than cells grown on all other surfaces. Because all novel materials facilitated the expression of the osteoblastic phenotype at least as much as TCP and the polystyrene control, these biomaterials can be regarded as excellent candidate bone substitute materials. GB9 induced the highest proliferation and cellular differentiation after 21 days of incubation, suggesting that this material may possess a higher potency for enhancing osteogenesis than TCP. © 2004 Wiley Periodicals, Inc. J Biomed Mater Res 69A: 145-154, 2004