Comparative effects of polyvinyl chloride microplastics on the brittle star Ophiactis virens and the amphibian Xenopus laevis.

In this study, we investigated the effects of PVC microplastics (PVC-MPs) using two different animal models: the brittle star Ophiactis virens, and the African clawed frog Xenopus laevis. This is the first study using an environmental relevant sample of PVC-MPs obtained through mechanical fragmentation of a common PVC plumbing pipe. Exposure experiments on brittle star were performed on the adult stage for a duration of 14 days, while those on African clawed frog were performed on the embryogenic developmental stage according to the standardized FETAX protocol (Frog Embryo Teratogenesis Assay-Xenopus). For both models, different endpoints were analysed: mortality, developmental parameters, behavioural assays and histological analyses on target organs by optical and electronic microscopy. Results showed that the concentration of 0.1 µg mL-1 PVC do not cause any adverse effects in both models (common NOEC concentration), while exposure to 1 µg mL-1 PVC adversely affected at least one species (common LOEC concentration). In particular arm regeneration efficiency was the most affected parameters in O. virens leading to a significantly lower differentiation pattern at 1 µg mL-1 PVC. On the contrary, in X. laevis larvae histopathological analyses and behavioural tests were the most susceptible endpoints, exhibiting several abnormal figures and different swimming speed at 10 µg mL-1 PVC. Histopathological analyses revealed a higher abundance of degenerating cells, pyknotic nuclei and cellular debris in the gut of exposed larvae in respect to control. The comparative analyses performed in this work allowed to characterize the specificity of action of the PVC-MPs on the two species, underlining the importance of exploring a large spectrum of endpoints to offer adequate protection in the emerging fields of microplastic research.

In Vitro Activity of the Arylaminoartemisinin GC012 against Helicobacter pylori and Its Effects on Biofilm.

This study evaluated the in vitro activity of the arylaminoartemisinin GC012, readily obtained from dihydroartemisinin (DHA), against clinical strains of Helicobacter pylori (H. pylori) with different antibiotic susceptibilities in the planktonic and sessile state. The activity was assessed in terms of bacteriostatic and bactericidal potential. The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) were determined by the broth microdilution method. After treatment with GC012, all bacterial strains showed significantly lower MIC and MBC values compared to those of DHA. The effect of combination of GC012 with antibiotics was examined using the checkerboard method. GC012 displayed synergistic interactions with metronidazole, clarithromycin, and amoxicillin in all the strains. The antibiofilm activity was evaluated via crystal violet staining, AlamarBlue® assay, colony-forming unit count, and fluorescence microscopy. At ½ MIC and » MIC concentration, both GC012 and DHA inhibited biofilm formation, but only GC012 showed a minimal biofilm eradication concentration (MBEC) on mature biofilm. Furthermore, both compounds induced structural changes in the bacterial membrane, as observed by transmission electron microscopy (TEM) and scanning electron microscopy (SEM). It is thereby demonstrated that GC012 has the potential to be efficacious against H. pylori infection.

Human airway organoids and microplastic fibers: A new exposure model for emerging contaminants.

Three-dimensional (3D) structured organoids are the most advanced in vitro models for studying human health effects, but their application to evaluate the biological effects associated with microplastic exposure was neglected until now. Fibers from synthetic clothes and fabrics are a major source of airborne microplastics, and their release from dryer machines is poorly understood. We quantified and characterized the microplastic fibers (MPFs) released in the exhaust filter of a household dryer and tested their effects on airway organoids (1, 10, and 50 µg mL-1) by optical microscopy, scanning electron microscopy (SEM), confocal microscopy and quantitative reverse transcription-polymerase chain reaction (qRT-PCR). While the presence of MPFs did not inhibit organoid growth, we observed a significant reduction of SCGB1A1 gene expression related to club cell functionality and a polarized cell growth along the fibers. The MPFs did not cause relevant inflammation or oxidative stress but were coated with a cellular layer, resulting in the inclusion of fibers in the organoid. This effect could have long-term implications regarding lung epithelial cells undergoing repair. This exposure study using human airway organoids proved suitability of the model for studying the effects of airborne microplastic contamination on humans and could form the basis for further research regarding the toxicological assessment of emerging contaminants such as micro- or nanoplastics.

Inner Ear and Muscle Developmental Defects in Smpx-Deficient Zebrafish Embryos.

The last decade has witnessed the identification of several families affected by hereditary non-syndromic hearing loss (NSHL) caused by mutations in the SMPX gene and the loss of function has been suggested as the underlying mechanism. In the attempt to confirm this hypothesis we generated an Smpx-deficient zebrafish model, pointing out its crucial role in proper inner ear development. Indeed, a marked decrease in the number of kinocilia together with structural alterations of the stereocilia and the kinocilium itself in the hair cells of the inner ear were observed. We also report the impairment of the mechanotransduction by the hair cells, making SMPX a potential key player in the construction of the machinery necessary for sound detection. This wealth of evidence provides the first possible explanation for hearing loss in SMPX-mutated patients. Additionally, we observed a clear muscular phenotype consisting of the defective organization and functioning of muscle fibers, strongly suggesting a potential role for the protein in the development of muscle fibers. This piece of evidence highlights the need for more in-depth analyses in search for possible correlations between SMPX mutations and muscular disorders in humans, thus potentially turning this non-syndromic hearing loss-associated gene into the genetic cause of dysfunctions characterized by more than one symptom, making SMPX a novel syndromic gene.

Myocardial hypoxic stress mediates functional cardiac extracellular vesicle release.

AIMS: Increased shedding of extracellular vesicles (EVs)-small, lipid bilayer-delimited particles with a role in paracrine signalling-has been associated with human pathologies, e.g. atherosclerosis, but whether this is true for cardiac diseases is unknown. METHODS AND RESULTS: Here, we used the surface antigen CD172a as a specific marker of cardiomyocyte (CM)-derived EVs; the CM origin of CD172a+ EVs was supported by their content of cardiac-specific proteins and heart-enriched microRNAs. We found that patients with aortic stenosis, ischaemic heart disease, or cardiomyopathy had higher circulating CD172a+ cardiac EV counts than did healthy subjects. Cellular stress was a major determinant of EV release from CMs, with hypoxia increasing shedding in in vitro and in vivo experiments. At the functional level, EVs isolated from the supernatant of CMs derived from human-induced pluripotent stem cells and cultured in a hypoxic atmosphere elicited a positive inotropic response in unstressed CMs, an effect we found to be dependent on an increase in the number of EVs expressing ceramide on their surface. Of potential clinical relevance, aortic stenosis patients with the highest counts of circulating cardiac CD172a+ EVs had a more favourable prognosis for transcatheter aortic valve replacement than those with lower counts. CONCLUSION: We identified circulating CD172a+ EVs as cardiac derived, showing their release and function and providing evidence for their prognostic potential in aortic stenosis patients.

Occurrence of microplastics in pellets from the common kingfisher (Alcedo atthis) along the Ticino River, North Italy.

Previous research has reported avian plastic ingestion in marine bird species. Yet, while research attention on plastic pollution is shifting from marine to freshwater ecosystems, very few information on plastic ingestion is available for freshwater birds. Here, we examined the presence of microplastic in regurgitated pellets of the common kingfisher (Alcedo atthis) collected along the Ticino River (North Italy). In total, 133 kingfisher's pellets were examined between March and October 2019 from 54 transects along the river. Plastic elements were detected and identified by visual inspection followed by µ-FTIR and SEM-EDS. Overall, we found 12 (micro)plastics from at least three different polymers in 7.5% of the pellets. This study provides the first report of plastic uptake of this bird species. It highlights the importance of spectroscopic techniques in plastic monitoring studies in order to avoid misidentification of items found. Documenting the presence of plastic ingestion by top carnivores such as fish-eating birds is necessary to understand the pervasiveness and impact of (micro)plastic pollution in food webs of freshwater ecosystems.

Does mechanical stress cause microplastic release from plastic water bottles?

Plastic particle ingestion has become of concern as a possible threat to human health. Previous works have already explored the presence of microplastic (MP) in bottled drinking water as a source of MP intake. Here, we consider the release of MP particles from single-use PET mineral water bottles upon exposure to mechanical stress utilizing SEM plus EDS, which allows the implementation of morphological and elemental analysis of the plastic material surface and quantification of particle concentrations in sample water. The aim of this study was to better evaluate the sources of MP intake from plastic bottles, especially considering the effect of daily use on these bottles such as the abrasion of the plastic material. For that, we analysed MP release of PET bottlenecks and HDPE caps on their surfaces after a series of bottle openings/closings (1 x, 10 x, 100 x). Furthermore, we investigated, if the inner surface of the PET bottles released MPs, counted particle increase of the water and identified MPs in the PET bottled water after exposing the bottles to mechanical stress (squeezing treatment; none, 1 min, 10 min). The results showed a considerable increase of MP particle occurrence on the surface of PET and HDPE material (bottlenecks and caps) after opening and closing the bottles. After 100 times the effect was impressive, especially on caps. Moreover, great differences exist in cap abrasion between brands which uncovers a discrepancy in plastic behavior of brands. Interestingly, particle concentrations in the bottled mineral water did not significantly increase after exposure to mechanical stress (squeezing treatment). The morphological analysis of the inner wall surface of the bottles supported this observation, as no stress cracks could be detected after the treatment, implying that the bottles itself are not a consistent source of MP particles after this extent of mechanical stress. However, chances of MP ingestion by humans increase with frequent use of the same single-use plastic bottle, though only from the bottleneck-cap system.

Polystyrene microplastics ingestion induced behavioral effects to the cladoceran Daphnia magna.

Microplastic (µPs) contamination represents a dramatic environmental problem threatening both aquatic and terrestrial organisms. Although several studies have highlighted the presence of µPs in aquatic environments, the information regarding their toxicity towards organisms is still scant. Moreover, most of the ecotoxicological studies of µPs have focused on marine organisms, largely neglecting the effects on freshwater species. The present study aimed at exploring the effects caused by 21-days exposure to three concentrations (0.125, 1.25 and 12.5 µg/mL) of two differently sized polystyrene microplastics (PµPs; 1 and 10 µm) to the Cladoceran Daphnia magna. The ingestion/egestion capability of daphnids (<24 h) and adults, the changes in individual growth and behavior, in terms of changes in swimming activity, phototactic behavior and reproduction, were investigated. Both particles filled the digestive tract of daphnids and adults within 24 h of exposure at all the tested concentrations. Ingested PµPs remained in the digestive tract even after 96 h in a clean medium. For both particles, an overall increase in body size of adults was noted at the end of the exposure to the highest tested concentrations, accompanied by a significant increase in swimming activity, in terms of distance moved and swimming velocity, and by an alteration of the phototactic behavior. A significant increase in the mean number of offspring after the exposure to the highest PµPs concentrations of different size was recorded. Polystyrene µPs can affect behavioral traits of D. magna leading to potentially harmful consequences on population dynamics of this zooplanktonic species.

Amyloid-ß Oligomers Regulate ADAM10 Synaptic Localization Through Aberrant Plasticity Phenomena.

A disintegrin and metalloproteinase 10 (ADAM10) is a synaptic enzyme that has been previously shown to limit amyloid-ß1-42 (Aß1-42) peptide formation in Alzheimer's disease (AD). Furthermore, ADAM10 participates to spine shaping through the cleavage of adhesion molecules and its activity is under the control of synaptic plasticity events. In particular, long-term depression (LTD) promotes ADAM10 synaptic localization triggering its forward trafficking to the synapse, while long-term potentiation elicits ADAM10 internalization. Here, we show that a short-term in vitro exposure to Aß1-42 oligomers, at a concentration capable of inducing synaptic depression and spine loss, triggers an increase in ADAM10 synaptic localization in hippocampal neuronal cultures. However, the Aß1-42 oligomers-induced synaptic depression does not foster ADAM10 delivery to the synapse, as the physiological LTD, but impairs ADAM10 endocytosis. Moreover, Aß1-42 oligomers-induced inhibition of ADAM10 internalization requires neuronal activity and the activation of the NMDA receptors. These data suggest that, at the synaptic level, Aß1-42 oligomers trigger an aberrant plasticity mechanism according to which Aß1-42 oligomers can downregulate Aß generation through the modulation of ADAM10 synaptic availability. Moreover, the increased activity of ADAM10 towards its synaptic substrates could also affect the structural plasticity phenomena. Overall, these data shed new lights on the strict and complex relationship existing between synaptic activity and the primary mechanisms of AD pathogenesis.

Polystyrene microplastics did not affect body growth and swimming activity in Xenopus laevis tadpoles.

A growing number of studies have highlighted the contamination and the effects towards organisms of diverse microplastics (µPs) in the marine environment. Surprisingly, although the main sources of µPs for marine environments are inland surface waters, the information on the occurrence and the effects of µPs in freshwater ecosystems is still scant. Thus, the aim of the present work is to investigate the ingestion and possible adverse effects due to the exposure to polystyrene µPs (PSµPs; Ø = 3 µm) on tadpoles of the Amphibian Xenopus laevis. Larvae at the developmental stage 36, prior to mouth opening, were exposed under semi-static conditions to 0.125, 1.25, and 12.5 µg mL-1 of PSµPs, and allowed to develop until stage 46. At the end of the exposure, the digestive tract and the gills from exposed and control tadpoles were microscopically examined, as well as changes in body growth and swimming activity. PSµPs were observed in tadpoles' digestive tract, but not in the gills, from each tested concentration. However, neither body growth nor swimming activity were affected by PSµPs exposure. Our results demonstrated that PSµPs can be ingested by tadpoles, but they did not alter X. laevis development and swimming behavior at least during early-life stages, also at high, unrealistic concentrations.

The interactions of fullerene C60 and Benzo(α)pyrene influence their bioavailability and toxicity to zebrafish embryos.

This study aimed to assess the toxicological consequences related to the interaction of fullerene nanoparticles (C60) and Benzo(α)pyrene (B(α)P) on zebrafish embryos, which were exposed to C60 and B(α)P alone and to C60 doped with B(α)P. The uptake of pollutants into their tissues and intra-cellular localization were investigated by immunofluorescence and electron microscopy. A set of biomarkers of genotoxicity and oxidative stress, as well as functional proteomics analysis were applied to assess the toxic effects due to C60 interaction with B(α)P. The carrier role of C60 for B(α)P was observed, however adsorption on C60 did not affect the accumulation and localization of B(α)P in the embryos. Instead, C60 doped with B(α)P resulted more prone to sedimentation and less bioavailable for the embryos compared to C60 alone. As for toxicity, our results suggested that C60 alone elicited oxidative stress in embryos and a down-regulation of proteins involved in energetic metabolism. The C60 + B(α)P induced cellular response mechanisms similar to B(α)P alone, but generating greater cellular damages in the exposed embryos.

Comparative toxicity of three differently shaped carbon nanomaterials on Daphnia magna: does a shape effect exist?

The acute toxicity of three differently shaped carbon nanomaterials (CNMs) was studied on Daphnia magna, comparing the induced effects and looking for the toxic mechanisms. We used carbon nano-powder (CNP), with almost spherical primary particle morphology, multi-walled carbon nanotubes (CNTs), tubes of multi-graphitic sheets, and cubic-shaped carbon nanoparticles (CNCs), for which no ecotoxicological data are available so far. Daphnids were exposed to six suspensions (1, 2, 5, 10, 20 and 50 mg L-1) of each CNM, and then microscopically analyzed. Ultrastructural analyses evidenced cellular uptake of nanoparticle in CNP and CNT exposed groups, but not in samples exposed to CNCs. Despite this difference, very similar effects were observed in tissues exposed to the three used CNMs: empty spaces between cells, cell detachment from the basal lamina, many lamellar bodies and autophagy vacuoles. These pathological figures were qualitatively similar among the three groups, but they differed in frequency and severity. CNCs caused the most severe effects, such as partial or complete dissolution of the brush border and thinning of the digestive epithelium. Being the cubic shape not allowed to be internalized into cells, but more effective than others in determining physical damages, we can conclude that shape is an important factor for driving nanoparticle uptake by cells and for determining the acute toxicological endpoints. Shape also plays a key role in determining the kind and the severity of pathologies, which are linked to the physical interactions of CNMs with the exposed tissues.

Sol-gel TiO2 colloidal suspensions and nanostructured thin films: structural and biological assessments.

The role of substrate topography in phenotype expression of in vitro cultured cells has been widely assessed. However, the production of the nanostructured interface via the deposition of sol-gel synthesized nanoparticles (NPs) has not yet been fully exploited. This is also evidenced by the limited number of studies correlating the morphological, structural and chemical properties of the grown thin films with those of the sol-gel 'brick' within the framework of the bottom-up approach. Our work intends to go beyond this drawback presenting an accurate investigation of sol-gel TiO2 NPs shaped as spheres and rods. They have been fully characterized by complementary analytical techniques both suspended in apolar solvents, by dynamic light scattering (DLS) and nuclear magnetic resonance (NMR) and after deposition on substrates (solid state configuration) by transmission electron microscopy (TEM) and powder x-ray diffraction (PXRD). In the case of suspended anisotropic rods, the experimental DLS data, analyzed by the Tirado-Garcia de la Torre model, present the following ranges of dimensions: 4-5 nm diameter (∅) and 11-15 nm length (L). These results are in good agreement with that obtained by the two solid state techniques, namely 3.8(9) nm ∅ and 13.8(2.5) nm L from TEM and 5.6(1) ∅ and 13.3(1) nm L from PXRD data. To prove the suitability of the supported sol-gel NPs for biological issues, spheres and rods have been separately deposited on coverslips. The cell response has been ascertained by evaluating the adhesion of the epithelial cell line Madin-Darby canine kidney. The cellular analysis showed that titania films promote cell adhesion as well clustering organization, which is a distinguishing feature of this type of cell line. Thus, the use of nanostructured substrates via sol-gel could be considered a good candidate for cell culture with the further advantages of likely scalability and interfaceability with many different materials usable as supports.

Chronic toxicity effects of ZnSO4 and ZnO nanoparticles in Daphnia magna.

The chronic toxicity of ZnSO4 and ZnO nanoparticles has been studied in Daphnia magna also considering the life cycle parameters beyond the standard 21-day exposure time. Specimens have been individually followed until the natural end of their life, and some of them sampled for microscopic analyses at 48h, 9 and 21 days. Despite the low level of exposure (0.3mg Zn/L), ultrastructural analyses of the midgut epithelial cells revealed efficient internalization of nanoparticles between 48h and 9d, and translocation to other tissues as well. At 21d, the most affected fields have been recorded for both compounds; in particular samples exposed to ZnO nanoparticles showed swelling of mitochondria, while those exposed to ZnSO4 had a great number of autophagy vacuoles. The life cycle parameters resulted altered as well, with a significant inhibition of reproduction in both groups, when compared to controls. After the 21-day exposure, some interesting results were obtained: animals, previously exposed to nanoZnO at low concentrations, showed a complete recovery of the full reproduction potential, while those previously exposed to ZnSO4 presented a dose-dependent and compound-specific reduction in lifespan. Based on the results from the present research and the effects of the same chemicals at higher doses, it can be concluded that the soluble form plays a key role in ZnO nanoparticle cytotoxicity, and that the nanoparticulate form is able to locally increase the amount of Zn inside the cell, even within the ovary. It's worth noting that ZnO nanoparticles have been internalized despite the very low concentration used: this raises concern about the possible environmental implications which may derive from their use, and which in turn must be carefully considered.

Role of soluble zinc in ZnO nanoparticle cytotoxicity in Daphnia magna: A morphological approach.

The role of soluble zinc has been determined in Daphnia magna by a morphological approach, integrating a previous paper in which the ultrastructural damages to gut epithelial cells have been studied after ZnO nanoparticles exposure. In the present paper, the toxicity and morphological effects of soluble zinc from ZnSO4 have been determined in a 48-h acute exposure test. Daphnids have been exposed to six nominal zinc concentrations (0.075, 0.15, 0.3, 0.6, 1.2, and 2.4mg Zn/L) and then fixed for microscopic analyses. Data from the acute toxicity tests gave an EC50 value of 0.99mg/L and showed that no immobilization appeared up to 0.3mg Zn/L. Ultrastructural analyses of samples from the two highest concentrations showed large vacuolar structures, swelling of mitochondria, multilamellar bodies, and a great number of autophagy vacuoles. These findings have been compared to those from our previous study, and similarities and/or differences discussed. Based on the overall results it can be concluded that dissolved zinc ions played a key role in ZnO nanoparticle toxicity and that the morphological approach is an extremely useful tool for comparing toxicological effects as well. A possible common toxic mechanism of soluble zinc and ZnO nanoparticles was also proposed.

Stem Cell-Mediated Exon Skipping of the Dystrophin Gene by the Bystander Effect.

Duchenne muscular dystrophy (DMD) is characterized by the loss of a functional dystrophin protein; the muscles of DMD patients progressively degenerate as a result of mechanical stress during contractions, and the condition eventually leads to premature death. By means antisense oligonucleotides (AONs), it is possible to modulate pre-mRNA splicing eliminating mutated exons and restoring dystrophin open reading frame. To overcome the hurdles in using AONs for therapeutic interventions, we exerted engineered human DMD stem cells with a lentivirus, which permanently and efficiently delivered the cloned AONs. Here we describe for the first time the exosome-mediated release of AONs from engineered human DMD CD133+ stem cells allowing the rescue of murine dystrophin expression. Finally, upon release, AONs could be internalized by host cells suggesting a potential role of exosomes acting as vesicular carriers for DMD gene therapy.

A novel non-aqueous sol-gel route for the in situ synthesis of high loaded silica-rubber nanocomposites.

Silica-natural rubber nanocomposites were obtained through a novel non-aqueous in situ sol-gel synthesis, producing the amount of water necessary to induce the hydrolysis and condensation of a tetraethoxysilane precursor by esterification of formic acid with ethanol. The method allows the synthesis of low hydrophilic silica nanoparticles with ethoxy groups linked to the silica surface which enable the filler to be more dispersible in the hydrophobic rubber. Thus, high loaded silica composites (75 phr, parts per hundred rubber) were obtained without using any coupling agent. Transmission Electron Microscopy (TEM) showed that the silica nanoparticles are surrounded by rubber layers, which lower the direct interparticle contact in the filler-filler interaction. At the lowest silica loading (up to 30 phr) silica particles are isolated in rubber and only at a large amount of filler (>60 phr) the interparticle distances decrease and a continuous percolative network, connected by thin polymer films, forms throughout the matrix. The dynamic-mechanical properties confirm that the strong reinforcement of the rubber composites is related to the network formation at high loading. Both the improvement of the particle dispersion and the enhancement of the silica loading are peculiar to the non-aqueous synthesis approach, making the method potentially interesting for the production of high-loaded silica-polymer nanocomposites.

Toxic effects and ultrastructural damages to Daphnia magna of two differently sized ZnO nanoparticles: does size matter?

The toxic effects of two differently sized ZnO nanopowders have been studied in Daphnia magna using advanced microscopy techniques. Five nanoZnO suspensions (0.1, 0.33, 1, 3.3 and 10 mg/L) were tested. The results of the 48-h acute toxicity tests performed with ZnO < 100 nm (bZnO) and ZnO < 50 nm (sZnO) showed slight effects, with EC50 values of 3.1 and 1.9 mg/L for bZnO and sZnO, respectively. Specimens exposed to 1 and 3.3 mg/L have been microscopically analysed and nanoparticles (NPs) from both concentrations have been found into midgut cells: i) in the microvilli; ii) in endocytic vesicles near the upper cell surface; iii) in some endosomes, as well as in mitochondria, in multivesicular and multilamellar bodies; iv) into the enterocytes' nuclei; v) free in the cytoplasm; vi) in the paracellular space between adjacent cells; vii) into the folded basal plasma membrane, and viii) in the gut muscolaris, suggesting that not only both nanoZnOs are able to interact with the plasmatic membrane of D. magna enterocytes, but also that they are capable to cross epithelial barriers. The ultrastructural changes increased with increasing concentrations and the worst morphological fields came from samples exposed to 3.3 mg/L of both nanoZnOs. Morphological effects were qualitatively similar between the two nanomaterials, but they appear to be much more frequent for sZnO NPs. Data from ICP-OES analyses demonstrated that the maximum Zn(++) concentration in our tested suspensions was 0.137 mg/L, which is well below the reported NOEC for the soluble Zinc. The corresponding Zn-salt exposures (0.1 mg/L Zn(++)) gave 0% of immobilized daphnids for both NPs suggesting that in our test medium nanoZnO toxicity is not driven by their solubilized ions. The large presence of NPs inside midgut cells after only 48-h exposure to nanoZnOs and their effects on the intestinal cells highlighted the toxic potential of these nanomaterials, also suggesting that studies on chronic effects are needed.

Evidence and uptake routes for Zinc oxide nanoparticles through the gastrointestinal barrier in Xenopus laevis.

The developmental toxicity of nanostructured materials, as well as their impact on the biological barriers, represents a crucial aspect to be assessed in a nanosafety policy framework. Nanosized metal oxides have been demonstrated to affect Xenopus laevis embryonic development, with nZnO specifically targeting the digestive system. To study the mechanisms of the nZnO-induced intestinal lesions, we tested two different nominally sized ZnO nanoparticles (NPs) at effective concentrations. Advanced microscopy techniques and molecular marker analyses were applied in order to describe the NP-epithelial cell interactions and the mechanisms driving NP toxicity and translocation through the intestinal barrier. We attributed the toxicity to NP-induced cell oxidative damage, the small-sized NPs being the more effective. This outcome is sustained by a marked increase in anti-oxidant genes' expression and high lipid peroxidation level in the enterocytes, where disarrangement of the cytoskeleton and cell junctions' integrity were evidenced. These events led to diffuse necrotic changes in the intestinal barrier, and trans- and paracellular NP permeation through the mucosa. The uptake routes, leading NPs to cross the intestinal barrier and reach secondary target tissues, have been documented. nZnOs embryotoxicity was confirmed to be crucially mediated by the NPs' reactivity rather than their dissolved ions. The ZnO NPs' ability to overwhelm the intestinal barrier must be taken into high consideration for a future design of safer ZnO NPs.

Mineral-organic hybrid nanotubes as highly sensitive solid state optical chemical sensors.

Hybrid materials represent one of the strategies of materials science for accomplishing complex functionalities hardly encompassed by single-component systems. The critical step in this approach is the mixing and/or bonding between the two different components, which must preserve the original characteristics of the materials or give rise to new functionalities originating from a proper and controlled interaction between the two components. Here, we demonstrate the use of the ionic self-assembly approach for fabricating functional nanomaterials comprising an inorganic matrix constituted by synthetic geomimetic chrysotile nanotubes and an organic superficial layer of a free-base porphyrin. The resulting hybrid nanomaterial can be processed as colloidal solution and as thin solid film. In both phases, the hybrid shows a bright red fluorescence under UV-blue excitation at ca. 400 nm. This fluorescence exhibits decreasing intensity with decreasing pH, as a result of the porphyrin J-type aggregation strongly catalyzed by the mineral surface. Simultaneously, the aggregation induces a neat color change from red to green, serving as a fast direct visual test of pH variations. These results open the route for the utilization of bio-compatible and inert mineral nanomaterials with strong adsorbing properties as efficient and cost-effective solid state vectors for functional molecules.