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Durante il mio dottorato, ho supportato la valutazione del rischio di nanomateriali focalizzandomi sulla caratterizzazione e controllo di proprietà e comportamenti che influenzano l'esposizione e che determinano meccanismi potenzialmente pericolosi per uomo e ambiente. Attraverso sei diverse nanoparticelle divise qui in cinque casi studio, ho impostato i progetti sperimentali per misurare le proprietà intrinseche (composizione, dimensione e morfologia), le dipendenti dal sistema (aggregazione e dissoluzione nei mezzi) e le proprietà correlate alla reattività delle nanoparticelle. Tutti i nanomateriali di riferimento e commerciali sono stati selezionati come rappresentativi di un'ampia classe di componenti al fine di massimizzare l'impatto complessivo della ricerca. In una prospettiva "read-across", tali nanoparticelle sono state selezionate come rappresentative di tre diverse classi di raggruppamento: solubili (Ag, CuO e ZnO), passive (SiO2) e attive (CeO2 e TiO2). Nel corso del lavoro ho affrontato tutti i casi di studio seguendo una caratterizzazione graduale a complessità crescente. In primo luogo, ho raccolto informazioni sulle proprietà intrinseche (dimensioni, forma, funzionalizzazione superficiale), che delineano la natura delle nanoparticelle, quindi ho disperso le nanoparticelle in mezzi (eco) tossici rilevanti, misurando le proprietà dipendenti dal sistema derivate dalle interazioni nanoparticelle / mezzo e infine, concentrandomi sull’esposizione umana, ho valutato la traslocazione delle nanoparticelle attraverso la cute umana e la mucosa orale con l’utilizzo del test ex-vivo in vitro di Franz. La caratterizzazione fisico-chimica delle nanoparticelle nei mezzi umani e ambientali pertinenti (distribuzione dimensionale, dissoluzione statica, potenziale zeta, cinetica della sedimentazione) può supportare la valutazione dell'esposizione, mentre i risultati in-vitro possono essere trasferiti alla valutazione del rischio delle nanoparticelle. Tramite i modelli in-silico dedicati, i dati in-vitro potrebbero essere ulteriormente implementati consentendo l'estrapolazione delle correlazioni esposizione-dose-risposta utilizzabili per implementare la valutazione del rischio. Pertanto, i risultati ottenuti a supporto dell'esposizione e della valutazione dei pericoli potrebbero essere applicati nella prima fase del processo CSA. During my PhD research activity, I supported the risk assessment of nanomaterials focusing on the characterization and control of their properties that drive potentially hazardous mechanisms affecting external and internal exposure. Particularly, I considered the exposure to both human and environmental targets. Throughout six different nanoparticles here organized into five case studies, I set up the experimental designs for measuring NMs intrinsic (composition, dimension and morphology), system-dependent (aggregation and dissolution in media) and fate related properties. Both reference and commercial nanomaterials were selected as representative of a wide class of components maximizing the overall impact of the research. In a “read-across” perspective, such nanoparticles were selected as representative of three different grouping classes: soluble (Ag, CuO and ZnO), passive (SiO2) and active (CeO2 and TiO2). I faced the case studies following a step by step characterization at increasing complexity. Firstly, I collected information on the intrinsic properties (size, shape, superficial functionalization), that outline the nanoparticles nature, then I dispersed the nanoparticles in relevant (eco)tox media, measuring the system-dependent properties derived from the nanoparticles/medium interaction and finally, moving toward the human exposure routes, I evaluated the in-vitro ex-vivo translocation through dermal or oral mucosa membranes with Franz cell tests. The nanoparticles physiochemical characterization in relevant human and environmental media (size distribution, static dissolution, zeta potential, sedimentation kinetic) may support the exposure assessment, while the in-vitro results may be transferred to the nanoparticles hazard evaluation. By means of the dedicated in-silico models the in-vitro data could be further implemented enabling the extrapolation of exposure-dose-response correlations usable to implement the risk assessment. Thus, the obtained results in support to exposure and hazard assessment could be applied in the first step of the CSA process.

Additional file 1: Figure S1: TEM micrographs of the ENM listed in Table 1: (A) TiO2 NM-105 (B) Ag Sigma (C) BaSO4 NM-220 (D) CeO2 NM-212 and (E) ZnO NM-111. Image (A), (B), (C) and (D) reproduced from Keller et al. (2020) ( https://doi.org/10.1080/17435390.2020.1836281 ) and image (E) reproduced from Yin et al. (2015) ( https://doi.org/10.1007/s11051-014-2851-y ). Figure S2: A series of XRD patterns for the five ENMs listed in Table 1, (A) TiO2 (NM-105), (B) Ag (Sigma 576832), (C) ZnO (NM-111), (D) BaSO4 (NM-220) and (E) CeO2 (NM-212). These graphs illustrate the crystalline phases for each material as summarised in Table 1. Figure S3: A series of XPS core level curves for the five ENMs included in this study and summarized in Table 1: TiO2 (NM-105), ZnO (NM-111), Ag (Sigma 576832), BaSO4 (NM-220) and CeO2 (NM-212). Each curve is fitted by Lorentzian-Gaussian convoluted functions to determine the chemical composition. Figure S4: Representative images of micronuclei generated by automated scoring of HepG2 cells using a Metafer MetaSystem 3.9.8. (A) illustrates an enlarged image of a micronucleus shown in the scoring gallery pictured in (D), and highlighted with an orange outline. Representative images of micronuclei found within the HepG2 mononucleate (B, C) and binucleate (E–G) cell populations following prolonged and acute ENM exposures respectively.

Herein we report the easy incorporation of brightly phosphorescent cationic iridium(III) tetrazole complexes into a silica based matrix via an easily scalable colloidal process. For this purpose, two cationic Ir(III) emitters bearing 5-aryl tetrazole ligands (R-CN4) were selected: blue [F2IrPTZ-Me]+ (C^N = F2ppy; N^N = PTZ-Me – 2-(2-methyl-2H-tetrazol-5-yl)pyridine) and red [IrQTZ-Me]+ (C^N = ppy; N^N = QTZ-Me – 2-(2-methyl-2H-tetrazol-5-yl)quinoline). The cationic complexes were readily adsorbed to negatively charged silica nanoparticles and trapped in the sol–gel matrix. The sol-to-solid phase transfer was performed by using an innovative spray-freeze-drying technique, leading to the formation of phosphorescent solid micro-granules. The structural and optical characterisation of the Ir(III) complexes together with SiO2 nanoparticles, nanosols (Ir@SiO2) and powders (Ir@SiO2 powders), revealed how the presence of the Ir(III)-based complexes did not alter the morphology of the colloidal silica or granulated phases. Moreover, the silica matrix did not interfere with the optical properties of the embedded complexes. The distribution of [F2IrPTZ-Me]+ and [IrQTZ-Me]+ in the spray-freeze-dried powders was qualitatively evaluated by fluorescence microscopy, revealing how the luminescent particles were homogeneously dispersed all over the silica matrix. Interestingly, in aqueous solution the release of complex [F2IrPTZ-Me]+ from the corresponding Ir@SiO2 powder is almost negligible, therefore suggesting that a strong interaction occurs between the host–silica matrix and the Ir(III) guest complex., This project has benefited from the EU-H2020 research program under grant agreement no. 654360 and has benefited from the access provided by the Fundacio Institut Català de Nanociència y Nanotecnologia – ICN2 – Barcelona (Spain) and the Foundation for Research and Technology Hellas – FORTH – Heraklion (Greece) within the framework of the NFFA-Europe Transnational Access Activity. The ICN2 is funded by the CERCA programme (Generalitat de Catalunya) and is supported by the Severo Ochoa programme of the Spanish Ministry of Economy, Industry and Competitiveness (MINECO, grant no. SEV-2013-0295). The authors wish to thank the Italian Ministry of Education, University and Research (MIUR) for their financial support (PRIN project: Towards a Sustainable Chemistry: Design of Innovative Metal–Ligand Systems for Catalysis and Energy Applications).

Magnetic nanoparticles (MNPs) present outstanding properties making them suitable as therapeutic agents for hyperthermia treatments. Since the main safety concerns of MNPs are represented by their inherent instability in a biological medium, strategies to both achieve long-term stability and monitor hazardous MNP degradation are needed. We combined a dynamic approach relying on flow field flow fractionation (FFF)-multidetection with conventional techniques to explore frame-by-frame changes of MNPs injected in simulated biological medium, hypothesize the interaction mechanism they are subject to when surrounded by a saline, protein-rich environment, and understand their behaviour at the most critical point of intravenous administration. In the first moments of MNPs administration in the patient, MNPs change their surrounding from a favorable to an unfavorable medium, i.e., a complex biological fluid such as blood; the particles evolve from a synthetic identity to a biological identity, a transition that needs to be carefully monitored. The dynamic approach presented herein represents an optimal alternative to conventional batch techniques that can monitor only size, shape, surface charge, and aggregation phenomena as an averaged information, given that they cannot resolve different populations present in the sample and cannot give accurate information about the evolution or temporary instability of MNPs. The designed FFF method equipped with a multidetection system enabled the separation of the particle populations providing selective information on their morphological evolution and on nanoparticle–proteins interaction in the very first steps of infusion. Results showed that in a dynamic biological setting and following interaction with serum albumin, PP-MNPs retain their colloidal properties, supporting their safety profile for intravenous administration.

A strategy for the design of cotton flame retardant coatings is described, exploiting the natural intumescent formulation of nucleic acids, the intrinsic thermal inertia of TiO2 ceramic phase and the strong affinity that TiO2 nanoparticles shows for amphiphilic biomolecules (e.g. proteins, nucleic acids) and hydrophilic substrates. Two different self-assembled TiO2@DNA systems are obtained by mixing two opposite charged TiO2 nanoparticles suspensions with DNA solution. The colloidal behavior of separate and mixed phases was investigated, as well as the morphological, chemical structure and thermal properties of resulting coatings, in order to make some hypothesis on the observed synergic effects. Scanning electron microscopy (SEM) and Attenuated Total Reflectance (ATR) spectroscopy demonstrated the homogeneous distribution of nano-TiO2@DNA based coatings on the treated fabrics. The washing fastness tests evidenced the highly improved performance of hybrid coatings if compared with DNA alone. The flammability and cone calorimetry test results confirmed this positive synergy that resulted quite effective in slowing down (or even blocking) the propagation of a flame within the treated substrates and in improving the resistance of the fabrics to the applied heat flux, these latter leaving increased residues at the end of the test. (C) 2019 Published by Elsevier Inc.

Two neutral cyclometalated Ir(III)-tetrazolato complexes that differ by variations of the substituents on either the phenylpyridine or the tetrazolate ligand have been converted into the corresponding methylated and cationic analogues. NMR (1H and 13C) characterization of the Ir(III) complexes provided the results in agreement with the chemo- and regioselective character of methylation at the N-3 position of the Ir(III)-coordinated tetrazolato ring. This evidence was further corroborated by the analysis of the molecular structures of the cationic complexes obtained by X-ray diffraction. In view of the photophysical properties, the addition of a methyl moiety to neutral Ir(III) tetrazolates, which behave as sky-blue or orange phosphors, caused a systematic red shift of their phosphorescence output. The transformation of neutral Ir(III) tetrazolates into cationic Ir(III)-tetrazole complexes was screened for any eventual antimicrobial activity in vitro against Gram negative (E. coli) and Gram positive (D. radiodurans) microorganisms. While both kinds of complexes were not active against E. coli, the conversion of the neutral Ir(III) tetrazolates into the corresponding methylated and cationic Ir(III)tetrazole derivatives determined the turn-on of a good to excellent antimicrobial activity toward Gram positive Deinococcus radiodurans, a non-pathogenic bacterium that is listed as one of the toughest microorganisms in light of its outstanding resistance to radiation and oxidative stress.