Roberta Pecoraro

Modification of graphene oxide by laser irradiation: a new route to enhance antibacterial activity.

The antibacterial activity and possible toxicity of graphene oxide and laser-irradiated graphene oxide (iGO) were investigated. Antibacterial activity was tested on Escherichia coli and shown to be higher for GO irradiated for at least three hours, which seems to be correlated to the resulting morphology of laser-treated GO and independent of the kind and amount of oxygen functionalities. X-ray photoelectron spectroscopy, Raman spectroscopy, dynamic light scattering and scanning electron microscopy (SEM) show a reduction of the GO flakes size after visible laser irradiation, preserving considerable oxygen content and degree of hydrophilicity. SEM images of the bacteria after the exposure to the iGO flakes confirm membrane damage after interaction with the laser-modified morphology of GO. In addition, a fish embryo toxicity test on zebrafish displayed that neither mortality nor sublethal effects were caused by the different iGO solutions, even when the concentration was increased up to four times higher than the one effective in reducing the bacteria survival. The antibacterial properties and the absence of toxicity make the visible laser irradiation of GO a promising option for water purification applications.

Toxic Effects of Zinc Chloride on the Bone Development in Danio rerio (Hamilton, 1822)

The increase of heavy metals in the environment involves a high exposure of aquatic organisms to these pollutants. The present study is planned to investigate the effects of zinc chloride (ZnCl2) on the bone embryonic development of Danio rerio and confirm the use of zebrafish as a model organism to study the teratogenic potential of this pollutant. Zebrafish embryos were exposed to different ZnCl2 concentrations and analyzed by ICP-MS. The skeletal anomalies were evaluated to confocal microscope after staining with calcein solution and RhodZinTM-3,AM. The data show a delay in hatching compared with the controls, malformations in the process of calcification and significant defects in growth. In conclusion, the current work demonstrates for the first time the Zn toxic effects on calcification process and confirm zebrafish (Danio rerio) as suitable alternative vertebrate model to study the causes and the mechanisms of the skeletal malformations.

Toxicity evaluation of graphene oxide and titania loaded nafion membranes in zebrafish

The use of nanomaterials in several application fields has received in the last decades a great attention due to their peculiar properties, but also raised many doubts about possible toxicity when these materials are used for some specific applications, such as water purification. Indeed a careful investigation is needed in order to exclude possible harmful side effects related to the use of nanotechnology. Nanoparticles effects on the marine organisms may depend on their chemical composition, size, surface structure, solubility, shape and how the individual nanoparticles aggregate together. In order to make the most of their potential, without polluting the environment, many researchers are trying to trap them into some kind of matrix that keeps them active but avoids their dispersion in the environment. In this study we have tested nanocomposite membranes prepared using Nafion polymer combined with various fillers, such as anatase-type TiO2 nanoparticles and graphene oxide. The non-toxicity of these nanocomposites, already shown to be effective for water purification applications in our previous studies, was recognized by testing the effect of the different materials on zebrafish embryos. Zebrafish was considered an excellent model for ecotoxicological studies and for this motivation zebrafish embryos were exposed to different concentrations of free nanoparticles and to the nanocomposite membranes. As biomarkers of exposure, we evaluated the expression of heme-oxygenase 1 and inducible Nitric Oxide Synthases by immunohistochemistry and gene expression. Embryo toxicity test showed that nor sublethal effects neither mortality were caused by the different nanoparticles and nano-systems tested. Only zebrafish larvae exposed to free nanoparticles have shown a different response to antibodies anti-heme-oxygenase 1 and anti- inducible Nitric Oxide Synthases. The immunolocalization analysis in fact has highlighted an increase in the synthesis of these biomarkers.

Toxicity Evaluation of New Engineered Nanomaterials in Zebrafish

The effect of the nanoparticles on the marine organisms, depends on their size, chemical composition, surface structure, solubility and shape. In order to take advantage from their activity, preserving the surrounding environment from a possible pollution, we are trying to trap the nanoparticles into new nanomaterials. The nanomaterials tested were synthesized proposing a ground-breaking approach by an upside-down vision of the Au/TiO2 nano-system to avoid the release of nanoparticles. The system was synthesized by wrapping Au nanoparticles with a thin layer of TiO2. The non-toxicity of the nano-system was established by testing the effect of the material on zebrafish larvae. Danio rerio o zebrafish was considered an excellent model for the environmental biomonitoring of aquatic environments and the Zebrafish Embryo Toxicity Test (ZFET) is considered an alternative method of animal test. For this reason zebrafish larvae were exposed to different concentrations of nanoparticles of TiO2 and Au and new nanomaterials. As biomarkers of exposure, we evaluated the expression of metallothioneins by immunohistochemistry analysis and western blotting analysis also. The results obtained by toxicity test showed that neither mortality as well as sublethal effects were induced by the different nanomaterials and nanoparticles tested. Only zebrafish larvae exposed to free Au nanoparticles showed a different response to anti-MT antibody. In fact, the immunolocalization analysis highlighted an increase of the metallothioneins synthesis.

Trace-Metal Enrichment and Pollution in Coastal Sediments in the Northern Tyrrhenian Sea, Italy

Abstract This study evaluated the distribution pattern and pollution of chromium, arsenic (As), manganese (Mn), nickel, lead, and copper in surface sediments along the northern Latium coast of the Tyrrhenian Sea in Italy. The enrichment factor, geoaccumulation index, and potential toxicity response index were used to evaluate the degree of contamination. These results show As and Mn contamination. The high enrichment and contamination levels of As and Mn are located in two hot spots. These elevations are due to naturally high levels of As and Mn in the Mignone River and the Marangone Stream as well as the intense human activity in the area including the largest energy production site in Europe (Torrevaldaliga Nord coal-fired power plant) and of one of the most important ports for cruise traffic in the Mediterranean Sea.

Evaluation of chronic nanosilver toxicity to adult zebrafish

Nanotechnology is rapidly growing with nanoparticles produced and utilized in a wide range of commercial products worldwide. Among the different types of nanomaterials produced, silver nanoparticles (AgNPs) occupy a predominant position and they are used in electronics, clothing, food industry, cosmetics and medical devices. Nanosilver has also showed excellent performance in antibacterial application. Nowadays, the increasing use of AgNPs has put the evidence on their possible toxicity to the human health and the impact on the environment. This paper focus on adverse effects of AgNPs in adult of Danio rerio. Fishes exposed to increasing concentrations (8, 45, and 70 μg/l) silver nanoparticles (AgNPs, 25 nm in average diameter) and after treatment for 30 days, was quickly euthanized in MS-222. We have evaluated bioaccumulation of AgNPs using ICP-MS and analyzed histological changes, biomarkers of oxidative damage and gene expression in the gut, liver and gills tissues of AgNPs-treated zebrafish. The histological analysis showed lesions of secondary lamellae of the gills with different degrees of toxicity such as hyperplasia, lamellar fusion, subepithelial edema, and even in some cases telangiectasia. Huge necrosis of the intestinal villi was found in the gut. No lesion was detected in the liver. The analysis revealed a high expression of metallothioneins 1 (MTs 1) in animals exposed to AgNPs compared to the control group. The ICP-MS analysis shows that the amount of particles absorbed in all treated samples is almost the same. We can affirm that AgNPs toxicity linked more to their size and state of aggregation than to their concentrations. Silver nanoparticles can damage gills and gut because they are able to pass through the mucosal barrier thanks to their small size. The damage is still reversible because it is not documented injury to the basal membrane.

Morphostructural and immunohistochemical study on the role of metallothionein in the detoxification of heavy metals in Apis mellifera L., 1758

Honey is a valuable food produced by bees from sugary substances that they gather in nature. The transformation the nectar into honey, by bees, is long and complex. Except for honey, where heavy metals are absent or are found only in traces, the bees and their products have always been considered excellent biomarkers of such contaminants. We have assumed that the absence of heavy metals in honey is due to the presence of a detoxification system in the digestive system of bees, which involves metallothioneins, proteins that have a role in the homeostatic control of essential and non‐essential metals. We have placed the beehives in three different zones: industrial, urban and rural. Investigations were carried out with ICP‐MS method for the detection of heavy metals in the guts of honey bees and honey. The metallothioneins have been identified by Immunohistochemical and Western‐blotting analisys. The investigations have shown the presence of heavy metals only in bees guts but not in honey, while the presence of metallothionein has been highlighted only in epithelium of the honey sac, demonstrating the existence of an efficient system of detoxification of heavy metals.

Mercury Enrichment in Sediments of the Coastal Area of Northern Latium, Italy

Abstract The purpose of this study was to evaluate the extent of the Hg geochemical anomaly arising in the Amiata and Tolfa complex to the coastal area of northern Latium and to examine the possible influence on this area by the Mignone River, and by the small coastal basins, which are characterized by both previous mining activities and decades of past industrial impact. The results confirm the extension of the anomaly of concentrations of Hg in the coastal area of northern Latium, with the northern sector influenced by the contributions of the Fiora and Mignone Rivers and the southern sector influenced by the contributions of minor basins. The results show high values of the Adverse Effect Index throughout the considered area and highlight the need for further investigation in order to assess the impact of human activities on the present and past values of Hg in marine sediments.

Metallic Nano‐Composite Toxicity Evaluation by Zebrafish Embryo Toxicity Test with Identification of Specific Exposure Biomarkers

Nanomaterials (NM) have different shapes and can be composed of different materials such as carbon, silicon, and some metals like gold, silver, and titanium. They are used as fillers, catalysts, semiconductors, cosmetics, drug carriers in medicine, energy storage systems, and antifriction coatings. NM are the parent compounds of nanoparticles (NPs), which may be divided into two groups: fullerenes and engineered nanoparticles (ENPs). After crossing the cell membrane, NPs may be stored in vesicles, mitochondria, and additional organelles within epithelial cells. They may generate reactive oxygen species, oxidative stress, and cytotoxicity, as well as denaturation of proteins, apoptosis, and necrosis. Nowadays, new toxicological data are required to assess the potential exposure of the environment and human beings to pollutants. The aim of the present investigation is to evaluate the toxicity of the metallic nano‐composite by the zebrafish embryo toxicity test (ZFET). The methods described here can be easily adapted to other nanocomposites or nanomaterials with some variations.

Teratogenic effects of the neonicotinoid thiacloprid on chick embryos (Gallus gallus domesticus)

Thiacloprid is an insecticide belonging to the family of neonicotinoids, substances initially underestimated for their potential adverse effects, that they may manifest in the long term leading to an extensive use. The objective of this study was to evaluate the effect at increasing concentrations of thiacloprid on chick embryos development. The research was carried out on 75 fertile eggs of Gallus gallus domesticus. The eggs were opened after 10, 15 and 20 days of incubation and in treated embryos were observed developmental alterations, growth retardation, limbs defects and ectopia viscerale. The histological analysis showed hepatic steatosis and haemorrhages both in the liver and in the lungs. Moreover, the immunohistochemical analysis performed on the liver sections showed a strong positivity only for the erythrocytes to the anti-CYP1A antibody. Thiacloprid exposure increases the risks of teratogenic effects especially at the higher doses tested, therefore its use should be more controlled and limited. Since the literature on the topic is lacking, then the human health impacts resulting from neonicotinoids exposure is not yet fully understood, and, our data will be helpful to allow the assessment of an oral reference dose and health risk characterization.