A Novel Strategy for the Detection and Quantification of Nanoplastics by Single Particle Inductively Coupled Plasma Mass Spectrometry (ICP-MS).

A method for the detection and quantification of nanoplastics (NPTs) at environmentally relevant concentrations was developed. It is based on conjugating nanoplastics with functionalized metal (Au)-containing nanoparticles (NPs), thus making them detectable by highly sensitive inductively coupled plasma mass spectrometry (ICP-MS) operated in single particle (SP) mode. The selectivity of the method was achieved by the coupling of negatively charged carboxylate groups present at the surface of nanoplastics with a positively charged gelatin attached to the custom-synthesized AuNPs. The adsorbed Au produced a SP-ICP-MS signal allowing the counting of individual nanoplastic particles, and hence their accurate quantification (<5% error). Polystyrene (PS) particle models with controlled surface functionalization mimicking the nanoplastics formed during natural degradation of plastic debris were used for the method development. The nanoplastic number concentration quantification limit was calculated at 8.4 × 105 NPTs L-1 and the calibration graph was linear up to 3.5 × 108 NPTs L-1. The method was applied to the analysis of nanoplastics of up to 1 µm in drinking, tap, and river water. The minimum detectable and quantifiable size depended on the degree of functionalization and the surface available for labeling. For a fully functionalized nanoplastic, the lower size detectable by this strategy is reported as 135 nm. In this study, authors use the recommendation for the definition of nanoplastics as plastic particles with sizes ranging between 1 nm and 1 µm, although it has not been accepted by a dedicated organization.

Microwave-Assisted and Metal-Induced Crystallization: A Rapid and Low Temperature Combination.

Here, we present a new crystallization process which, by combining microwaves and metal-induced devitrification, reduces both the time and the temperature of crystallization compared to other known methods. Titania crystallization initiates at a temperature as low as 125 °C within a few minutes of microwave radiation. Several cations induce this low-temperature crystallization, namely, Mn2+, Co2+, Ni2+, Al3+, Cu2+ and Zn2+. The crystallization mechanism is probed with electron microscopy, elemental mapping, single-particle inductively coupled plasma mass spectrometry, X-ray photoelectron spectroscopy, Auger electron spectroscopy, and scanning Auger mapping. These techniques show that the metal ion migration through the vitreous titania under microwave radiation occurs prior to crystallization. The crystalline particles are suspended in solution at the end of the treatment, avoiding particle aggregation and sintering. The crystalline suspensions are thus ready for processing into a material or employment in any other application. This combination of microwaves and metal-induced crystallization is applied here to TiO2, but we are investigating its application to other materials as an ecofriendly crystallization method.

Core@Corona Functional Nanoparticle-Driven Rod-Coil Diblock Copolymer Self-Assembly.

Herein, a novel strategy to overcome the influence of π-π stacking on the rod-coil copolymer organization is reported. A diblock copolymer poly(3-hexylthiophene)-block-poly(ethylene glycol methyl ether methacrylate) (P3HT-b-PEGMA) was synthesized by the Huisgen cycloaddition, so-called "click chemistry", combining the PEGMA and P3HT blocks synthesized by atom transfer radical polymerization and Kumada catalyst transfer polymerization, respectively. Using a dip-coating process, we controlled the original film organization of the diblock copolymer by the crystallization of the P3HT block via π-π stacking. The morphology of the P3HT-b-PEGMA films was influenced by the incorporation of gold nanoparticles (GNPs) coated by poly(ethylene glycol) ligands. Indeed, the crystalline structuration of the P3HT sequence was counterbalanced by the addition in the film of gold nanoparticles finely localized within the copolymer PEGMA matrix. Transmission electron microscopy and time-of-flight secondary ion mass spectrometry analysis validated the GNP homogeneous localization into the compatible PEGMA phase. Differential scanning calorimetry showed the rod block crystallization disruption. A morphological transition of the self-assembly is observed by atomic force microscopy from P3HT fibrils into out-of-plane cylinders driven by the nanophase segregation.

Design and Cellular Fate of Bioinspired Au-Ag Nanoshells@Hybrid Silica Nanoparticles.

Silica-coated gold-silver alloy nanoshells were obtained via a bioinspired approach using gelatin and poly-l-lysine (PLL) as biotemplates for the interfacial condensation of sodium silicate solutions. X-ray photoelectron spectroscopy was used as an efficient tool for the in-depth and complete characterization of the chemical features of nanoparticles during the whole synthetic process. Cytotoxicity assays using HaCaT cells evidenced the detrimental effect of the gelatin nanocoating and significant induction of late apoptosis after silicification. In contrast, PLL-modified nanoparticles had less biological impact that was further improved by the silica layer, and uptake rates of up to 50% of those of the initial particles could be achieved. These results are discussed considering the effect of nanosurface confinement of the biopolymers on their chemical and biological reactivity.

Reactivity at the Electrode-Electrolyte Interfaces in Li-Ion and Gel Electrolyte Lithium Batteries for LiNi0.6Mn0.2Co0.2O2 with Different Particle Sizes.

The layered oxide LiNi0.6Mn0.2Co0.2O2 is a very attractive positive electrode material, as shown by the good reversible capacity, chemical stability, and cyclability upon long-range cycling in Li-ion batteries and, hopefully, in the near future, in all-solid-state batteries. Three samples with variable primary particle sizes of 240 nm, 810 nm, and 2.1 µm on average and very similar structures close to the ideal 2D layered structure (less than 2% Ni2+ ions in Li+ sites) were obtained by coprecipitation followed by a solid-state reaction at high temperatures. The electrochemical performances of the materials were evaluated in a conventional organic liquid electrolyte in Li-ion batteries and in a gel electrolyte in all-solid-state batteries. The positive electrode/electrolyte interface was analyzed by X-ray photoelectron spectroscopy to determine its composition and the extent of degradation of the lithium salt and the carbonate solvents after cycling, taking into account the changes in particle size of the positive electrode material and the nature of the electrolyte.

AES and ToF-SIMS combination for single cell chemical imaging of gold nanoparticle-labeled Escherichia coli.

A chemical fingerprint of the Escherichia coli cell surface labeled by gelatin coated gold nanoparticles was obtained by combining Auger Electron Spectroscopy (AES) for single cell level chemical images, and Time-of-Flight Secondary Ion Mass Spectroscopy (ToF-SIMS) Tandem MS for unambiguous molecular identification of co-localized species.

A nanopatterned dual reactive surface driven by block copolymer self-assembly.

Herein, we report the selective functionalization of nano-domains obtained by the self-assembly of a polystyrene-block-poly(vinyl benzyl azide) PS-b-PVBN3 copolymer synthesized in three steps. First, a polystyrene macro-initiator was synthesized, and then extended with vinyl benzyl chloride by nitroxide mediated polymerization to form polystyrene-block-poly(vinyl benzyl chloride) PS-b-PVBC. Nucleophilic substitution of vinyl benzyl chloride into a vinyl benzyl azide moiety is finally performed to obtain PS-b-PVBN3 which self-assembled into nano-domains of vinyl benzyl azide PVBN3. Click chemistry was then used to bind functional gold nanoparticles and poly(N-isopropylacrylamide) (PNIPAM) on PVBN3 domains due to the specific anchoring at the surface of the nanopatterned film. Atomic force microscopy (AFM) was used to observe the block copolymer self-assembly and the alignment of the gold nanoparticles at the surface of the PVBN3 nanodomains. Thorough X-ray photoelectron spectroscopy (XPS) analysis of the functional film showed evidence of the sequential grafting of nanoparticles and PNIPAM. The hybrid surface expresses thermo-responsive properties and serves as a pattern to perfectly align and control the assembly of inorganic particles at the nanoscale.

Gold@Prussian blue analogue core-shell nanoheterostructures: their optical and magnetic properties.

Au@Prussian-Blue Analogue (PBA) shell nanoheterostructures are multifunctional nano-objects combining optical properties (surface plasmon resonance) of the Au core and magnetic properties of the PBA shell. We report in this article a series of new Au core@PBA shell nano-objects with different PBA shells: Au@K/Co/[FeII(CN)6] (2) and Au@K/Ni/[CrIII(CN)6]:[FeII(CN)6] (3) single PBA shell, as well as Au@K/Ni/[FeII(CN)6]@K/Ni/[FeIII(CN)6] (4) double PBA shell and Au@K/Ni/[FeII(CN)6]@K/Ni/[FeIII(CN)6]@K/Ni/[CrIII(CN)6] (5) triple PBA shell systems. The position and intensity of the Au SPR band, as well as the magnetic behaviour of the nanoheterostructures, are strongly affected by the shell composition and its thickness.

Gold and silver quantification from gold-silver nanoshells in HaCaT cells.

A method to determine total gold (Au) and/or silver (Ag) elemental concentrations from gold nanoparticles, Au-Ag nanoshells (NS) and silica coated Au-Ag nanoshells was developed, evaluated and validated. Samples were mineralized in a mixture of concentrated aqua regia and hydrofluoric acid at 65 °C for 4 h. Mineralized solutions were diluted and standard solutions were prepared in aqua regia 5%. ICP-MS analysis was performed with or without the use of a reaction cell (CRC). For the determination of elemental concentrations of nanopowders and test suspensions, the average recovery was 99 ±â€¯2% and 101 ±â€¯2% for gold and silver respectively. The repeatability was evaluated by the Relative Standard Deviation (RSD). The overall analytical RSD was ≤4% (n = 3) and the RSD associated to ICP-MS analysis was ≤2% (n = 10). The limits of detection were 0.005 and 0.002 µg(element) L-1 (analyzed solution), and the limits of quantitation 0.017 and 0.005 µg(element) L-1 (analyzed solution), for 197Au and 109Ag respectively. The Ag/Au mass ratios of the NS in the different samples considered were all equal to (0.93 ±â€¯0.04). From this information, the average thickness of gold and silver layers in the nanoshells was deduced, being 7.5 ±â€¯0.5 and 23 ±â€¯3 nm respectively. Finally, the developed method was successfully applied to in vitro studies to evaluate NS cellular uptake in HaCaT keratinocyte cells confirming the method robustness toward biological medium. Experiments in cell culture medium gave coherent concentrations, 70-100% of uncoated or silica-coated NS being recovered, distributed between the culture medium and the cells (internalized). The analytical repeatability (over the whole procedure, or that of the ICP-MS analysis only) remains in the same order of magnitude as in test suspensions. Minimum concentrations less than or equal to 1 µg(element) g-1(suspension) were determined with the same accuracy.

Design of iron oxide/silica/alginate hybrid magnetic carriers (HYMAC).

A large number of natural and synthetic polymers have already been evaluated for the design of nanomaterials incorporating magnetic nanoparticles for biomedical applications. The possibility to use hybrid (bio)-organic/inorganic nano-carriers have been much less studied. Here we describe the design of Hybrid MAgnetic Carriers (HYMAC) consisting of alginate/silica nanocomposites incorporating magnetite nanoparticles, based on a spray-drying approach. Transmission electron microscopy and X-ray energy dispersive spectrometry confirm the successful incorporation of magnetic colloids within homogeneous hybrid capsules. X-ray diffraction data suggest that surface iron ions are partially desorbed by the spray-drying process, leading to the formation of lepidocrocite and of an iron silicate phase. Magnetic measurements show that the resulting nanocomposites exhibit a superparamagnetic behaviour with a blocking temperature close to 225 K. Comparison with un-silicified capsules indicate that the mineral phase enhances the thermal stability of the polymer network and do not modify of the amount of incorporated iron oxide nanoparticles. Moreover, evaluation of nanocomposite up-take by fibroblasts indicates their possible internalization. A selective intracellular alginate degradation is observed, suggesting that these HYMAC nanomaterials may exhibit interesting properties for the design of drug delivery devices.

Potentialities of silica/alginate nanoparticles as hybrid magnetic carriers.

The possibility to associate traditional bio-organic capsules, such as polymer nanoparticles or liposomes, with silica has been recently demonstrated, opening the route to the design of novel nanocomposites that exhibit promising properties as drug carriers. In this context, we describe here the elaboration of silica/alginate nanoparticles incorporating magnetic iron oxide colloids and fluorescent carboxy-fluoroscein. These nanocomposites were characterized by electron microscopy, X-ray diffraction and magnetic measurements. The release of the fluorophore was investigated in vitro and was demonstrated to occur in 3T3 fibroblast cells. Further grafting of organic moieties on particle surface is also described. These data suggest that hybrid nanoparticles are flexible platforms for the developments of multi-functional bio-capsules.

Morphology and Surface Reactivity Relationship in the Li1+xMn2-xO4 Spinel with x = 0.05 and 0.10: A Combined First-Principle and Experimental Study.

This article focuses on the surface reactivity of two spinel samples with different stoichiometries and crystal morphologies, namely Li1+xMn2-xO4 with x = 0.05 and 0.10. LiMn2O4 compounds are good candidates as positive electrode of high-power lithium-ion batteries for portable devices. The samples were investigated using both experimental and theoretical approaches. On the experimental point of view, they were characterized in depth from X-ray diffraction, scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) analyses. Then, the reactivity was investigated through the adsorption of (SO2) gaseous probes, in controlled conditions, followed by XPS characterization. First-principle calculations were conducted simultaneously to investigate the electronic properties and the reactivity of relevant surfaces of an ideal LiMn2O4 material. The results allow us to conclude that the reactivity of the samples is dominated by an acido-basic reactivity and the formation of sulfite species. Nonetheless, on the x = 0.05 sample, both sulfite and sulfate species are obtained, the later, in lesser extent, corresponding to a redox reactivity. Combining experimental and theoretical results, this redox reactivity could be associated with the presence of a larger quantity of Mn4+ cations on the last surface layers of the material linked to a specific surface orientation.

Surface Reactivity of Li2MnO3: First-Principles and Experimental Study.

This article deals with the surface reactivity of (001)-oriented Li2MnO3 crystals investigated from a multitechnique approach combining material synthesis, X-ray photoemission spectroscopy (XPS), scanning electron microscopy, Auger electron spectroscopy, and first-principles calculations. Li2MnO3 is considered as a model compound suitable to go further in the understanding of the role of tetravalent manganese atoms in the surface reactivity of layered lithium oxides. The knowledge of the surface properties of such materials is essential to understand the mechanisms involved in parasitic phenomena responsible for early aging or poor storage performances of lithium-ion batteries. The surface reactivity was probed through the adsorption of SO2 gas molecules on large Li2MnO3 crystals to be able to focus the XPS beam on the top of the (001) surface. A chemical mapping and XPS characterization of the material before and after SO2 adsorption show in particular that the adsorption is homogeneous at the micro- and nanoscale and involves Mn reduction, whereas first-principles calculations on a slab model of the surface allow us to conclude that the most energetically favorable species formed is a sulfate with charge transfer implying reduction of Mn.

Design of Magnetic Gelatine/Silica Nanocomposites by Nanoemulsification: Encapsulation versus in Situ Growth of Iron Oxide Colloids.

The design of magnetic nanoparticles by incorporation of iron oxide colloids within gelatine/silica hybrid nanoparticles has been performed for the first time through a nanoemulsion route using the encapsulation of pre-formed magnetite nanocrystals and the in situ precipitation of ferrous/ferric ions. The first method leads to bi-continuous hybrid nanocomposites containing a limited amount of well-dispersed magnetite colloids. In contrast, the second approach allows the formation of gelatine-silica core-shell nanostructures incorporating larger amounts of agglomerated iron oxide colloids. Both magnetic nanocomposites exhibit similar superparamagnetic behaviors. Whereas nanocomposites obtained via an in situ approach show a strong tendency to aggregate in solution, the encapsulation route allows further surface modification of the magnetic nanocomposites, leading to quaternary gold/iron oxide/silica/gelatine nanoparticles. Hence, such a first-time rational combination of nano-emulsion, nanocrystallization and sol-gel chemistry allows the elaboration of multi-component functional nanomaterials. This constitutes a step forward in the design of more complex bio-nanoplatforms.

Generation of a mesoporous silica MSU shell onto solid core silica nanoparticles using a simple two-step sol-gel process.

Silica core-shell nanoparticles with a MSU shell have been synthesized using several non-ionic poly(ethylene oxide) based surfactants via a two step sol-gel method. The materials exhibit a typical worm-hole pore structure and tunable pore diameters between 2.4 nm and 5.8 nm.

Simultaneous conductivity and viscosity measurements as a technique to track emulsion inversion by the phase-inversion-temperature method.

Two kinds of transitions can occur when an emulsified water-oil-ethoxylated nonionic surfactant system is cooled under constant stirring. At a water-oil ratio close to unity, a transitional inversion takes place from a water-in-oil (W/O) to an oil-in-water (O/W) morphology according to the so-called phase-inversion-temperature method. At a high water content, a multiple w/O/W emulsion changes to a simple O/W emulsion. The continuous monitoring of both the emulsion conductivity and viscosity allows the identification of several phenomena that take place during the temperature decrease. In all cases, a viscosity maximum is found on each side of the three-phase behavior temperature interval and correlates with the attainment of extremely fine emulsions, where the best compromise between a low-tension and a not-too-unstable emulsion is reached. The studied system contains Polysorbate 85, a light alkane cut oil, and a sodium chloride brine. All transitions are interpreted in the framework of the formulation-composition bidimensional map.