Nanoparticles devoted to improve radiotherapy treatments are an efficient tool if they can induce the formation of deleterious species in the tumor. Their interaction with radiation is responsible for radical production but in spite of the numerous studies mostly with cells, no consensus has been reached about radical formation mechanism. In order to gain knowledge in the physico-chemical step of this phenomenon, we applied a very sensitive test to quantify hydroxyl radicals and electrons produced when gold atoms, organized as nanoparticles or as a salt in solution, are irradiated by keV and MeV photons (x- and gamma- rays). The crucial role of interfacial water is suggested to explain the high quantity of radicals measured for nanoparticles. These experimental data were supplemented by classical molecular dynamics simulations, revealing a specific organization of the water hydrogen bonding network at the nanoparticle surface which could be a key component in the mechanism of radical production by irradiated colloidal suspensions.

Ever since studies on diamond nanoparticles (NDs) expanded, their exceptional colloidal stability was investigated as it is a key parameter for their further use in many applications. While a sonication step is required to deaggregate NDs and obtain stable aqueous suspensions, few works focused on the impact of the sonication process on the suspension composition. High-powered sonication induces the formation of a variety of species by radical pathways including nitrite and nitrate ions, which may act as radical or electron scavengers. Such effect may significantly affect the expected photocatalytic or radiolytic properties of NDs. This work aims to warn about the formation of these ionic species during the deagglomeration of NDs by sonication. Our investigation reveals for the first time that for oxidized detonation NDs, such treatment promotes the formation of additional NO2- ions and hydroxyl radicals, suggesting an increase in cavitation bubbles formation. Hydrogenated particles on the opposite present no overproduction of nitrite ions. Our results also show that these species can be avoided in suspension by sonicating under controlled atmosphere with no significant perturbation of NDs colloidal stability or surface chemistry.

Background Synthetic amorphous silica nanoparticles (SAS-NPs) are widely employed in pharmaceutics, cosmetics, food and concretes. Workers and the general population are exposed daily via diverse routes of exposure. SAS-NPs are generally recognized as safe (GRAS) by the Food and Drug Administration, but because of their nanoscale size and extensive uses, a better assessment of their immunotoxicity is required. In the presence of immune “danger signals”, dendritic cells (DCs) undergo a maturation process resulting in their migration to regional lymph nodes where they activate naive T-cells. We have previously shown that fumed silica pyrogenic SAS-NPs promote the two first steps of the adaptative immune response by triggering DC maturation and T-lymphocyte response, suggesting that SAS-NPs could behave as immune “danger signals”. The present work aims to identify the mechanism and the signalling pathways involved in DC phenotype modifications provoked by pyrogenic SAS-NPs. As a pivotal intracellular signalling molecule whose phosphorylation is associated with DC maturation, we hypothesized that Spleen tyrosine kinase (Syk) may play a central role in SAS-NPs-induced DC response. Results In human monocyte-derived dendritic cells (moDCs) exposed to SAS-NPs, Syk inhibition prevented the induction of CD83 and CD86 marker expression. A significant decrease in T-cell proliferation and IFN-γ, IL-17F and IL-9 production was found in an allogeneic moDC:T-cell co-culture model. These results suggested that the activation of Syk was necessary for optimal co-stimulation of T-cells. Moreover, Syk phosphorylation, observed 30 min after SAS-NP exposure, occurred upstream of the c-Jun N-terminal kinase (JNK) Mitogen-activated protein kinases (MAPK) and was elicited by the Src family of protein tyrosine kinases. Our results also showed for the first time that SAS-NPs provoked aggregation of lipid rafts in moDCs and that MβCD-mediated raft destabilisation altered Syk activation. Conclusions We showed that SAS-NPs could act as an immune danger signal in DCs through a Syk-dependent pathway. Our findings revealed an original mechanism whereby the interaction of SAS-NPs with DC membranes promoted aggregation of lipid rafts, leading to a Src kinase-initiated activation loop triggering Syk activation and functional DC maturation.

Among the different nanodiamonds, milled nanodiamonds (MNDs) from high-pressure high-temperature synthesis exhibit a crystalline quality close to that of the bulk diamond, making it a serious candidate for quantum or energy-related fields. In this study, MND aqueous suspensions with oxidized (MND-Ox) and hydrogenated (MND-H) surface chemistries were irradiated with gamma-rays. Using optimized nanoparticle-compatible methods, we revealed that MNDs in suspension enhance the production of solvated electrons under irradiation, with a higher yield for MND-H. Also, for the first time, a surface-chemistry-dependent scavenging effect of hydroxyl radicals was highlighted for this type of nanodiamonds.

Single phase Li4Ti5O12 powder with porous particle structure is synthesized via a simple, mild and productive citric-acid combustion method. The Li4Ti5O12 particle is composed of submicro-scaled grains with size of 100–200 nm. The synthesized Li4Ti5O12 shows high reversible capacity (ca. 165 mAh g−1 at 0.5 C), excellent rate-capability (ca. 115 and 100 mAh g−1 at 10 and 20 C, respectively) and high temperature cycling stability (50 °C). Under expanded cut-off voltage range of 0.01–2.5 V, it delivers a high specific capacity of ca. 230 and 170 mAh g−1 at 0.5 and 10 C, respectively, while maintaining an excellent cycling stability. The synthesized Li4Ti5O12 shows fast de-lithiation but slow lithiation kinetic processes. When discharged at constant 1 C while charged at 10, 20 and 30 C, respectively, the specific capacity of 162, 160 and 158 mAh g−1 can be achieved. The excellent electrochemical performance of the combustion synthesized Li4Ti5O12 is ascribed to the porous particle structure and small grain size feature, which ensure the good contact with electrolyte and reduce the lithium ion/electron diffusion distance, and therefore enhance the electrode reaction process.

The present study aims to compare the early stages of graphitization of the same DND source for two annealing atmospheres (primary vacuum, argon at atmospheric pressure) in an identical set-up. DND samples are finely characterized by a combination of complementary techniques (FTIR, Raman, XPS, HR-TEM) to highlight the induced modifications for temperature up to 1100 °C. The annealing atmosphere has a significant impact on the graphitization kinetics with a higher fraction of sp2-C formed under vacuum compared to argon for the same temperature. Whatever the annealing atmosphere, carbon hydrogen bonds are created at the DND surface during annealing according to FTIR. A "nano effect", specific to the <10 nm size of DND, exalts the extreme surface chemistry in XPS analysis. According to HR-TEM images, the graphitization is limited to the first outer shell even for DND annealed at 1100 °C under vacuum.

While subjected to radiation, gold nanoparticles (GNPs) have been shown to enhance the production of radicals when added to aqueous solutions. It has been proposed that the arrangement of water solvation layers near the water-gold interface plays a significant role. As such, the structural and electronic properties of the first water solvation layer surrounding GNPs of varying sizes were compared to bulk water using classical molecular dynamics and quantum and semi-empirical methods. Classical molecular dynamics was used to understand the change in macroscopic properties of bulk water in the presence of different sizes of GNP, as well as by including salt ions. The analysis of these macroscopic properties has led to the conclusion that larger GNPs induce the rearrangement of water molecules to form a 2D hydrogen-bond network at the interface. Quantum methods were employed to understand the electronic nature of the interaction between water molecules and GNPs along with the change in the water orientation and the vibrational density of states. The stretching region of vibrational density of states was found to extend into the higher wavenumber region, as the size of the GNP increases. This extension represents the dangling water molecules at the interface, as a result of reorientation of the water molecules in the first solvation shell. This multi-level study suggests that in the presence of GNP of increasing sizes, the first water solvation shell undergoes a rearrangement to maximize the water-water interactions as well as the water-GNP interactions.

Innate immune cells such as dendritic cells (DCs) sense and engulf nanomaterials potentially leading to an adverse immune response. Indeed, as described for combustion-derived particles, nanomaterials could be sensed as danger signals, enabling DCs to undergo a maturation process, migrate to regional lymph nodes and activate naive T lymphocytes. Synthetic amorphous silica nanoparticles (SAS-NPs) are widely used as food additives, cosmetics, and construction materials. This work aimed to evaluate in vitro the effects of manufactured SAS-NPs, produced by thermal or wet routes, on human DCs functions and T-cell activation. Human monocyte-derived DCs (moDCs) were exposed for 16 h to 3 endotoxin-free test materials: fumed silica NPs from Sigma-Aldrich (no. S5505) or the JRC Nanomaterial Repository (NM-202) and colloidal LudoxTMA NPs. Cell viability, phenotypical changes, cytokines production, internalization, and allogeneic CD4+ T-cells proliferation were evaluated. Our results showed that all SAS-NPs significantly upregulated the surface expression of CD86 and CD83 activation markers. Secretions of pro-inflammatory cytokines (CXCL-8 and CXCL-12) were significantly enhanced in a dose-dependent manner in the moDCs culture supernatants by all SAS-NPs tested. In an allogeneic coculture, fumed silica-activated moDCs significantly increased T-lymphocyte proliferation at all T-cell: DC ratios compared with unloaded moDCs. Moreover, analysis of coculture supernatants regarding the production of T-cell-derived cytokines showed a significant increase of IL-9 and IL-17A and F, as well as an upregulation of IL-5, consistent with the pro-inflammatory phenotype of treated moDCs. Taken together, these results suggest that SAS-NPs could induce functional moDCs maturation and play a role in the immunization process against environmental antigens.

In numerous fields of application (environmental remediation, catalysis, nanomedicine), production of hydroxyl radicals and solvated electrons by nanomaterials is a cornerstone. Through a very sensitive, nanoparticle-compatible, coumarin-based protocol, we quantified hydroxyl radicals in solution when hydrogenated (H-ND) and oxidized (Ox-ND) detonation nanodiamonds were irradiated by MeV photons. We highlighted a blatant difference between the two surface chemistries as only H-ND led to 50% more radicals, for irradiation doses and ND concentrations relevant in nanomedicine. For the first time, we also quantified solvated electrons after keV irradiation of both suspensions and showed that in the presence of H-ND, hydroxyl radicals and solvated electrons were available in solution in equivalent and higher amounts than in water only. This asks the question of the mechanisms at stage and beside the negative/positive electron affinity hypothesis usually mentioned, we proposed, as for other nanomaterials, that interfacial water could play an essential role in radicals’ production in solution when detonation H-ND are irradiated.

The CHIMACTIV website (http://chimactiv.agroparistech.fr/) offers open educational resources related to analytical chemistry. It addresses a frequently encountered pedagogical issue: How can we encourage students to be more involved in learning during their courses (and especially during lab work) as well as provide a deeper teacher–learner interaction during these sessions? With 30 digital bilingual (English/French) sections divided into 5 topics (safety in a chemistry lab, basics of manipulation, food analysis, drug analysis, and familiarity with experimental methodologies), CHIMACTIV offers a great variety of media (scientific content, short videos, interactive diagrams, pictures, games, quizzes, and exercises) which are responsive to all formats of the digital medium (computer, tablet, smartphone). Depending on their educational objectives and their students' curricula, teachers can guide students toward the appropriate resources to strengthen their backgrounds, build new scientific understanding, or analyze data. These digital resources may be consulted before, during, or after class and/or lab sessions, and they are ideal for students aiming to self-train, for trainees in research laboratories, as well as for professionals working in a sector related to chemical analysis.

As the nanotechnology market expands and the prevalence of allergic diseases keeps increasing, the knowledge gap on the capacity of nanomaterials to cause or exacerbate allergic outcomes needs more than ever to be filled. Engineered nanoparticles (NP) could have an adjuvant effect on the immune system as previously demonstrated for particulate air pollution. This effect would be the consequence of the recognition of NP as immune danger signals by dendritic cells (DCs). The aim of this work was to set up an in vitro method to functionally assess this effect using amorphous silica NP as a prototype. Most studies in this field are restricted to the evaluation of DCs maturation, generally of murine origin, through a limited phenotypic analysis. As it is essential to also consider the functional consequences of NP-induced DC altered phenotype on T-cells biology, we developed an allogeneic co-culture model of human monocyte-derived DCs (MoDCs) and CD4+ T-cells. We demonstrated that DC: T-cell ratios were a critical parameter to correctly measure the influence of NP danger signals through allogeneic co-culture. Moreover, to better visualize the effect of NP while minimizing the basal proliferation inherent to the model, we recommend testing three different ratios, preferably after five days of co-culture.

Nanoparticles are being developed for a wide range of medical applications such as, controlled release, drug delivery systems or imagery, theranostics, implants .... For the moment, there is no legal definition of nanoparticles or nanomaterials for therapeutic use. The specific case of gold nanoparticles is not an exception: their current definition as nanoparticle material does not correspond to classic pharmaceutical ingredients as described in Pharmacopoeias. In this study, more than 30 different batches of citrate stabilized gold nanoparticles (AuNP) were synthesized and analyzed thanks to both classical approaches (UV-Vis spectrophotometry, dynamic light scattering coupled or not to electrophoresis ...) and capillary zone electrophoresis (CZE) coupled to diode array detection to assess their purity and impurity profiles. These techniques led to the beginning of defined specifications, a key step for the use of gold nanoparticles as pharmaceutical ingredients. CZE was demonstrated suitable to evaluate a batch-to-batch quality control, to monitor the purification processes and to follow the stability of 18 different batches for 20 days. Finally, commercially available AuNP samples were tested and the results compared to the provided certificates of analysis.