Critical aspects in dissolution testing of nanomaterials in the oro-gastrointestinal tract: the relevance of juice composition for hazard identification and grouping.

The dissolution of a nanomaterial (NM) in an simulant of the oro-gastrointestinal (OGI) tract is an important predictor of its biodurability . The cascade addition of simulated digestive juices (saliva, stomach and intestine), including inorganic/organic biomacromolecules and digestive enzymes (complete composition, referred to as "Type 1 formulation"), strives for realistic representation of chemical composition of the OGI tract. However, the data robustness requires consideration of analytical feasibility, such as the use of simplified media.

Reproducibility of methods required to identify and characterize nanoforms of substances.

Nanoforms (NFs) of a substance may be distinguished from one another through differences in their physicochemical properties. When registering nanoforms of a substance for assessment under the EU REACH framework, five basic descriptors are required for their identification: composition, surface chemistry, size, specific surface area and shape. To make the risk assessment of similar NFs efficient, a number of grouping frameworks have been proposed, which often require assessment of similarity on individual physicochemical properties as part of the group justification.

Refinement of the selection of physicochemical properties for grouping and read-across of nanoforms.

Before placing a new nanoform (NF) on the market, its potential adverse effects must be evaluated. This may e.g.

Comparative assessment of the fate and toxicity of chemically and biologically synthesized silver nanoparticles to juvenile clams.

Nanoparticles (NPs) can be produced via physical, chemical, or biological approaches. Yet, the impact of the synthesis approaches on the environmental fate and effects of NPs is poorly understood. Here, we synthesized AgNPs through chemical and biological approaches (cit-AgNPs and bio-AgNPs), characterized their properties, and toxicities relative to commercially available Ag nanopowder (np-AgNPs) to the clam Mercenaria mercenaria.

Stormwater green infrastructures retain high concentrations of TiO engineered (nano)-particles.

Stormwater conveys natural and engineered (nano)-particles, like any other pollutants, from urban areas to water resources. Thus, the use of stormwater green infrastructures (SGI), which infiltrate and treat stormwater, can potentially limit the spread of engineered (nano)-particles in the environment. However, the concentration of engineered (nano)-particles in soil or biofilter media used in SGI has not been measured due to difficulties in distinguishing natural vs.

Analysis of engineered nanomaterials (Ag, CeO and FeO) in spiked surface waters at environmentally relevant particle concentrations.

Quantification of engineered nanomaterials (ENMs) concentrations in surface waters remains one of the key challenges in environmental nanoscience and nanotechnology. A promising approach to estimate metal and metal oxide ENM concentrations in complex environmental samples is based on the increase in the elemental ratios of ENM-contaminated samples relative to the corresponding natural background elemental ratios. This contribution evaluated the detection and quantification of Ag, CeO, and FeO ENMs spiked in synthetic soft, or in natural river waters using the elemental ratio approach, and evaluated the effect of extractants including sodium hydroxide (NaOH), sodium oxalate (NaCO) and sodium pyrophosphate (NaPO) on the recovery of ENMs from the spiked waters.

Sewage spills are a major source of titanium dioxide engineered (nano)-particles into the environment.

Sanitary sewer overflows (SSOs) are a common problem across the United States. An estimated 23,000-75,000 SSOs occurred annually in 2004 discharging between 11 and 38 billion liters of untreated wastewater to receiving waters. SSOs release many contaminants, including engineered nanomaterials (ENMs), to receiving water bodies.

Dispersion of natural nanomaterials in surface waters for better characterization of their physicochemical properties by AF4-ICP-MS-TEM.

Characterization and understanding of natural nanomaterials (NNMs) properties is essential to differentiate engineered nanomaterials (ENMs) from NNMs. However, NNMs in environmental samples typically occur as heteroaggregates with other particles, e.g.

Improved extraction efficiency of natural nanomaterials in soils to facilitate their characterization using a multimethod approach.

Characterization of natural nanomaterial (NNM) physicochemical properties - such as size, size distribution, elemental composition and elemental ratios - is often hindered by lack of methods to disperse NNMs from environmental samples. This study evaluates the effect of extractant composition, pH, and ionic strength on soil NNM extraction in term of recovery and release of primary particles/small aggregate sizes (i.e.

Wire-Active Microrheology to Differentiate Viscoelastic Liquids from Soft Solids.

Viscoelastic liquids are characterized by a finite static viscosity and a yield stress of zero, whereas soft solids have an infinite viscosity and a non-zero yield stress. The rheological nature of viscoelastic materials has long been a challenge and is still a matter of debate. Here, we provide for the first time the constitutive equations of linear viscoelasticity for magnetic wires in yield-stress materials, together with experimental measurements by using magnetic rotational spectroscopy (MRS).

Manufactured Nanoparticle Behavior and Transformations in Aquatic Systems. Importance of Natural Organic Matter.

Major concerns to elucidate the fate of nanomaterials and manufactured nanoparticles in aquatic systems are related to the lack of data on nanoparticle transformations under relevant environmental conditions. The present article discusses some of the important physicochemical processes controlling the behavior of manufactured nanoparticles in aqueous systems by focusing on their interaction with natural organic matter, which is expected to play a crucial role when adsorbing at the nanoparticle surface. The precise knowledge and consequences of such adsorption processes are important not only to predict the nanoparticle stability and dispersion state but also to evaluate their chemical reactivity and ecotoxicology.

Formation of complexes between hematite nanoparticles and a non-conventional galactomannan gum. Toward a better understanding on interaction processes.

The physicochemical characteristics of hematite nanoparticles related to their size, surface area and reactivity make them useful for many applications, as well as suitable models to study aggregation kinetics. For several applications (such as remediation of contaminated groundwater) it is crucial to maintain the stability of hematite nanoparticle suspensions in order to assure their arrival to the target place. The use of biopolymers has been proposed as a suitable environmentally friendly option to avoid nanoparticle aggregation and assure their stability.

Towards a better understanding on agglomeration mechanisms and thermodynamic properties of TiO₂ nanoparticles interacting with natural organic matter.

Interaction between engineered nanoparticles and natural organic matter is investigated by measuring the exchanged heat during binding process with isothermal titration calorimetry. TiO2 anatase nanoparticles and alginate are used as engineered nanoparticles and natural organic matter to get an insight into the thermodynamic association properties and mechanisms of adsorption and agglomeration. Changes of enthalpy, entropy and total free energy, reaction stoichiometry and affinity binding constant are determined or calculated at a pH value where the TiO2 nanoparticles surface charge is positive and the alginate exhibits a negative structural charge.

Effect of electrolyte valency, alginate concentration and pH on engineered TiO₂ nanoparticle stability in aqueous solution.

Agglomeration and disagglomeration processes are expected to play a key role on the fate of engineered nanoparticles in natural aquatic systems. These processes are investigated here in detail by studying first the stability of TiO2 nanoparticles in the presence of monovalent and divalent electrolytes at different pHs (below and above the point of zero charge of TiO2) and discussing the importance of specific divalent cation adsorption with the help of the DLVO theory as well as the importance of the nature of the counterions. Then the impact of one polysaccharide (alginate) on the stability of agglomerates formed under pH and water hardness representative of Lake Geneva environmental conditions is investigated.

TiO2 nanoparticles aggregation and disaggregation in presence of alginate and Suwannee River humic acids. pH and concentration effects on nanoparticle stability.

The behavior of manufactured TiO2 nanoparticles is studied in a systematic way in presence of alginate and Suwannee River humic acids at variable concentrations. TiO2 nanoparticles aggregation, disaggregation and stabilization are investigated using dynamic light scattering and electrophoretic experiments allowing the measurement of z-average hydrodynamic diameters and zeta potential values. Stability of the TiO2 nanoparticles is discussed by considering three pH-dependent electrostatic scenarios.

Clickosomes--using triazole-linked phospholipid connectors to fuse vesicles.

Two complementary artificial diether phospholipids were synthesized that can undergo a Cu(I)-catalyzed Huisgen-Sharpless click reaction. The resulting lipid can bridge the membranes of large unilamellar vesicles and cause their aggregation and ultimately their fusion.