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We proved the possibility of electron gap tuning of graphene-based materials, using extensive first principles modelling of the structural, electronic and optical properties of partially hydrogenated graphene. Optical tools were proposed to characterize the hydrogenation process. Sub-monolayer hydrogen passivated graphene and various hydrogen induced superstructures were considered. Electron and optical DFT LDA gaps between 0.2 and 1.8 eV, suitable for microelectronic application, were obtained for low hydrogen coverage structures. For such systems, hydrogen clustering (by saturating neighbouring C dangling bonds at opposite sides of the graphene sheet) is energetically most favourable and generally produces a larger gap. A more homogeneous H distribution with one-side bonding to C-host atoms is, in contrast, less energetically favourable and even structurally unstable. In addition, such H configurations generally produce lower electron band gap. Hydrogen at low coverage not only locally buckles six-fold carbon rings, it leads to dimerization and subsequent electron localization for neighbouring carbon atoms, which are not H bonded. Such structural and electronic processes are responsible for gap opening and its magnitude. Calculated linear optical response indicates that the optics is not only gap sensitive, but, combined with experimental spectra, can also provide access to microscopic properties of 2D nano-sheets such as symmetry, hydrogen induced structure, degree of hydrogenation, chemical bonding, and others (© 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [ABSTRACT FROM AUTHOR]

The production and use of nanomaterials (NMs) has increased over the last decades posing relevant questions on their risk after release and exposure of the population or sub-populations. In this context, the safe and sustainable by design (SSbD) approach framework requires to assess the potential hazard connected with intrinsic properties of the material along the whole life cycle of the NM and/or of the nano enabled products. Moreover, in the last years, the use of new advanced methodologies (NAMs) has increasingly gained attention for the use of alternative methods in obtaining relevant information on NMs hazard and risk. Considering the SSbD and the NAMs frameworks, within the ASINA H2020 project, we developed new NAMs devoted at improving the hazard and risk definition of different Ag and TiO2 NPs. The NAMs are developed considering two air liquid interface exposure systems, the Vitrocell Cloud-α and the Cultex Compact module and the relevant steps to obtain reproducible exposures are described. The new NAMs build on the integration of environmental monitoring campaigns at nano-coating production sites, allowing the quantification by the multiple-path particle dosimetry (MPPD) model of the expected lung deposited dose in occupational settings. Starting from this information, laboratory exposures to the aerosolized NPs are performed by using air liquid interface exposure equipment and human alveolar cells (epithelial cells and macrophages), replicating the doses of exposure estimated in workers by MPPD. Preliminary results on cell viability and inflammatory responses are reported. The proposed NAMs may represent possible future reference procedures for assessing the NPs inhalation toxicology, supporting risk assessment at real exposure doses., Competing Interests: Declaration of Competing Interest The authors declare the following financial interests/personal relationships which may be considered as potential competing interests: All authors reports financial support was provided by European CommissionASINA (Anticipating Safety Issues at the Design Stage of Nano Product Development)European Project (H2020-GA 862444). All authors reports a relationship with European Commission ASINA (Anticipating Safety Issues at the Design Stage of Nano Product Development)) European Project (H2020-GA 862444) that includes: funding grants. If there are other authors, they declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024 The Authors. Published by Elsevier Ltd.. All rights reserved.)

The Safe-by-Design (SbD) concept aims to facilitate the development of safer materials/products, safer production, and safer use and end-of-life by performing timely SbD interventions to reduce hazard, exposure, or both. Early hazard screening is a crucial first step in this process. In this review, for the first time, commonly used in vitro assays are evaluated for their suitability for SbD hazard testing of nanomaterials (NMs). The goal of SbD hazard testing is identifying hazard warnings in the early stages of innovation. For this purpose, assays should be simple, cost-effective, predictive, robust, and compatible. For several toxicological endpoints, there are indications that commonly used in vitro assays are able to predict hazard warnings. In addition to the evaluation of assays, this review provides insights into the effects of the choice of cell type, exposure and dispersion protocol, and the (in)accurate determination of dose delivered to cells on predictivity. Furthermore, compatibility of assays with challenging advanced materials and NMs released from nano-enabled products (NEPs) during the lifecycle is assessed, as these aspects are crucial for SbD hazard testing. To conclude, hazard screening of NMs is complex and joint efforts between innovators, scientists, and regulators are needed to further improve SbD hazard testing.