3D printing for cyclonic spray chambers in ICP spectrometry

International audienceAdditive manufacturing (AM) or 3D-printing is an increasingly widespread technique which is often described as a source for rapid prototyping whereas it is a manufacturing process in itself. It is a new tool for instrumental research laboratories which can now easily manufacture by themselves a large variety of devices. This article describes its application to ICP introduction system spray chambers. We undertake to print and study cyclone spray chambers by combining and comparing for the first time 3 different AM processes, 5 materials and 8 designs. The analytical performances of these spray chambers are compared with commercial glass and PFA chambers in terms of signal intensity, stability, oxide ratio, LOD and wash-out time. LODs measured with polymer printed chambers are in the range or even outperform those measured with the glass chamber even though 3D-printed chambers provide lower results in terms of sensitivity than glass. Compared to PFA chambers, the printed chambers are superior in terms of LOD. At low temperature, the printed chambers' efficiency depends on both AM process and manufacturing material. SLA and FDM printers give lower results in terms of sensitivity but not in LOD than the Polyjet printer. This study also illustrates the influence of the inner shape of the side arm nebulizer and confirms the importance of a free aerosol recirculation current around the nebulizer tip. Transfer tube efficiency is also questioned; it is found to be weakly detrimental to the sensitivity to light elements but shows no influence on heavy ones as well as on the stability or oxide ratio, whatever the element

Contribution to SPICPMS Accurate Spherical Gold Nanoparticles Size Determination: a Comparison with Small Angle X-ray Scattering

International audienceSmall Angle X-rays Scattering Spectroscopy (SAXS) is the method of choice for nanopar-ticle diameter and concentration determination. It is metrologically traceable for spherical nanoparticle mean diameter determination and does not require any sample preparation or calibration. On the other hand, Single Particle ICPMS (SPICPMS) is still under developments and requires involved process clarification and accuracy improvement. The strategy of this presentation based on 6 spherical gold nanoparticle suspensions distributed over a large size range (30, 50, 60, 80,100 and150 nm), is the comparison of the two techniques to study comprehensively SPICPMS performance and observe phenomena: Potential matrix effect are eliminated by stabilizing nanoparticles with chitosan in HCL. Chitiosan encapsulates nanoparticles, stabilizes their dispersion and protects them from dissolution. Detection counting/analog threshold and timeout appear as the relevant parameters for transient signals. They show an influence not only on mean signal but also on signal distribution. The detection tuning proposed allow to linearly calibrate the nanoparticle distribution signal to cubed diameter over the entire range studied with no sensitivity diminution. Comparing the 3 classical transport efficiency methods (number, size and waste), size transport efficiency is shown as the most accurate. A procedure is proposed, it is validated analyzing three gold nanoparticles suspensions (135, 40 and 50nm). The results are consistent with SAXS measurements

Contribution to Accurate Spherical Gold Nanoparticles Size Determination by Single Particle Inductively Coupled Mass Spectrometry: a Comparison with Small Angle X-ray Scattering

International audienceSmall Angle X-rays Scattering Spectroscopy (SAXS) is the method of choice for nanoparticle diameter and concentration determination. It is metrologically traceable for spherical nanoparticle mean diameter determination and does not require any sample preparation or calibration. On the other hand, Single Particle ICPMS (SPICPMS) is still under developments and requires involved process clarification and accuracy improvement. The strategy of this study is the comparison of the two techniques to study comprehensively SPICPMS performance and observe phenomena otherwise hidden. 6 spherical gold nanoparticle suspensions distributed over a large size range (30, 50, 60, 80,100 and150 nm) are studied as standards. Potential matrix effect are eliminated by stabilizing nanoparticles with chitosan in HCL. Chitiosan encapsulates nanoparticles, stabilizes their dispersion and protects them from dissolution. Detection counting/analog threshold and timeout appear as the relevant parameters for transient signals. They show an influence not only on mean signal but also on signal distribution. The detection tuning proposed allow to linearly calibrate the nanoparticle distribution signal to cubed diameter over the entire range studied with no sensitivity diminution. Comparing the 3 classical transport efficiency methods, size transport efficiency is shown as the most accurate. The new procedure is validated analyzing three gold nanoparticles suspensions (135, 40 and 50nm). The results are consistent with SAXS measurements

Synthesis of SiO2 Nanoparticles as reference materials : metrology measurements and in situ kinetics in lab by Small angle –X-ray scattering

International audienceThe unambiguous correlation of possible health and sustainability risks to nanoparticle size must be enabled by reliable measurement of nanoparticle size, to ensure comparability and compatibility between results measured under different methods. The NPSIZE project funded by European Metrology Program (EMPIR) develop methods, reference materials and modelling to improve the traceability chain,comparability and compatibility of nanoparticle size measurements.In this work, we present how spherical silica nanoparticles are synthetized with controlled monomodal or bimodal dispersion to be use as reference materials and international round-robin. Improving the fabrication requires a fine understanding of synthesis (1), coupled with an expertise of in-situ or ex-situ analysis methods. This is a new challenge for the analysis : determining not only average characteristics (size, chemical composition and shape ...) but also the concentration and the distribution over the population studied (2).Small-Angle X-ray Scattering (3) allows very precise measurements of the nanoparticles size and concentration that can be directly link to the metric system (4) (metrological traceability) . We developed a SAXS laboratory instrument dedicated to the in-situ characterization of nanoparticles, which enable fast measurements, and the monitoring of the synthesis parameters. Measurement protocols and software processing chain (5) (i.e. size distribution) are also combined & optimized. TE

Exploring hybrid imogolite nanotubes formation via Si/Al stoichiometry control

International audienceHybrid imogolite aluminosilicate nanotubes with methylated internal surface can be obtained by introduction of the corresponding organosilane during their synthesis. However, similarly to pristine imogolite, a number of side-products, including proto-imogolite (open-imoLS), allophanes and aluminum hydroxides, are formed, that ultimately impact on the properties of the dispersions. In order to minimize the proportion of these side-products, we have here systematically explored the impact of the initial Si/Al ratio on the content of hybrid imogolite dispersions before and after dialysis. By combining cryo-TEM, ICPMS, IR spectroscopy and Small Angle X-ray Scattering, we evidenced that the Si/Al ratio has a large impact on the formation of aluminum hydroxides that can be minimized with a slight excess of Si precursor. However, a large excess of Si is detrimental to the reaction yield leading to an important proportion of proto-imogolite. We propose that the optimal Si/Al ratio of ca. 0.6 can both minimize the proportion of aluminum hydroxides and proto-imogolite. These results suggest that the dynamic and therefore reactive character of Imogolite dispersions may have been so far underlooked

How Nanoparticles Modify Adsorbed Proteins: Impact of Silica Nanoparticles on the Hemoglobin Active Site

International audienceThe adsorption of proteins on surfaces has been studied for a long time, but the relationship between the structural and functional properties of the adsorbed protein and the adsorption mechanism remains unclear. Using hemoglobin adsorbed on silica nanoparticles, we have previously shown that hemoglobin’s affinity towards oxygen increases with adsorption. Nevertheless, it was also shown that there were no significant changes in the quaternary and secondary structures. In order to understand the change in activity, we decided in this work to focus on the active sites of hemoglobin, the heme and its iron. After measuring adsorption isotherms of porcine hemoglobin on Ludox silica nanoparticles, we analyzed the structural modifications of adsorbed hemoglobin by X-ray absorption spectroscopy and circular dichroism spectra in the Soret region. It was found that upon adsorption, there were modifications in the heme pocket environment due to changes in the angles of the heme vinyl functions. These alterations can explain the greater affinity observed

Cucurbit[5]uril derivatives as oxygen carriers

International audienceCucurbit[n]urils are rigid cage-molecules of pumpkin-like shape, made of n-glycoluril units, able to bind mainly neutral molecules and cations. In this work, we investigate the binding of three cucurbit[5]uril derivatives with dioxygen O$_2$ and show that one of them, namely per-hydroxylated cucurbit[5]uril, (OH)$_{10}$CB[5], is able to significantly bind dioxygen gas at physiological temperature, even in the presence of sodium chloride at the concentration of injectable solution in blood. As cucurbit[n]urils studied up to now reveal low toxicity, per-hydroxylated cucurbit[5]uril appears as a promising precursor to design a host able to transport O$_2$ in a haemoglobin substitute solution

Development of a new hybrid approach combining AFM and SEM for the nanoparticle dimensional metrology

International audienceAt this time, there is no instrument capable of measuring a nano-object along the three spatial dimensions with a controlled uncertainty. The combination of several instruments is thus necessary to metrologically characterize the dimensional properties of a nano-object. This paper proposes a new approach of hybrid metrology taking advantage of the complementary nature of atomic force microscopy (AFM) and scanning electron microscopy (SEM) techniques for measuring the main characteristic parameters of nanoparticle (NP) dimensions in 3D. The NP area equivalent, the minimal and the maximal Feret diameters are determined by SEM and the NP height is measured by AFM. In this context, a kind of new NP repositioning system consisting of a lithographed silicon substrate has been specifically developed. This device makes it possible to combine AFM and SEM size measurements performed exactly on the same set of NPs. In order to establish the proof-of-concept of this approach and assess the performance of both instruments, measurements were carried out on several samples of spherical silica NP populations ranging from 5 to 110 nm. The spherical nature of silica NPs imposes naturally the equality between their height and their lateral diameters. However, discrepancies between AFM and SEM measurements have been observed, showing significant deviation from sphericity as a function of the nanoparticle size

Combining surface chemistry modification and in situ small-angle scattering characterization to understand and optimize the biological behavior of nanomedicines

International audienceNanomedicines are considered as promising therapeutics for cancer treatment. However, clinical translation is still scarce, partly because their biological behavior is not well understood. Extracting general guidelines from the great variety of nanoparticles and conditions studied is indeed difficult, and relevant techniques are lacking to obtain in situ information. Here, both issues are solved by combining versatile model nanoparticles with in situ tools based on small-angle scattering techniques (SAS). The strategy was to develop a library of nanoparticles and perform systematic study of their interactions with biological systems. Considering the promising properties of gold nanoparticles as cancer therapeutics, polymethacrylate-grafted gold nanoparticles were chosen as models. Modulation of polymer chemistry was shown to change the surface properties while keeping the same structure for all nanoparticles. This unity allowed reliable comparison to extract general principles, while the synthesis versatility enabled to fine-tune the nanoparticles surface properties, especially through copolymerization, and thus to optimize their biological behavior. Two specific aspects were particularly examined: colloidal stability and cell uptake. Positive charges and hydrophobicity were identified as key parameters influencing toxicity and internalization. In situ SAS gave valuable information about nanoparticles evolution in biologically relevant environments. Good colloidal stability was thereby shown in cell culture media, while intracellular transformation and quantity of nanoparticles were monitored, highlighting the potential of these techniques for nanomedicines studies