Browsing by Author "Matos, A. Alves de"
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- Comparação dos efeitos de exposição a nanopartículas de TiO2 em duas espécies de peixes de água doce: Danio rerio e Carassius auratusPublication . Diniz, M. S.; Lourenço, Joana; Matos, A. Alves de; Peres, Isabel; Castro, Luísa; Ferreira, Isabel; Barquinha, Pedro; Fortunato, Elvira; Silva, Luís; Mendonça, E.; Picado, Ana
- Histological and biochemical effects of exposure to TiO2 nanoparticles in livers of two freshwater fish species: Carassius auratus and Danio rerioPublication . Diniz, M. S.; Matos, A. Alves de; Lourenço, Joana; Castro, Luísa; Peres, Isabel; Mendonça, E.; Picado, Ana
- Histological and ultrastructural observations of daphina magna exposed to diamon nanoparticlesPublication . Matos, A. Alves de; Diniz, M. S.; Mendonça, E.; Peres, I.; Silva, Luís; Correia, J.B.; Picado, Ana
- A multi-integrated approach on toxicity effects of engineered TiO2 nanoparticlesPublication . Picado, Ana; Paixão, Susana M.; Moita, Liliana; Silva, Luís; Diniz, M. S.; Lourenço, Joana; Peres, Isabel; Castro, Luísa; Correia, J.B.; Pereira, Joana; Ferreira, Isabel; Matos, A. Alves de; Barquinha, Pedro; Mendonça, E.The new properties of engineered nanoparticles drive the need for new knowledge on the safety, fate, behavior and biologic effects of these particles on organisms and ecosystems. Titanium dioxide nanoparticles have been used extensively for a wide range of applications, e.g, self-cleaning surface coatings, solar cells, water treatment agents, topical sunscreens. Within this scenario increased environmental exposure can be expected but data on the ecotoxicological evaluation of nanoparticles are still scarce. The main purpose of this work was the evaluation of effects of TiO2 nanoparticles in several organisms, covering different trophic levels, using a battery of aquatic assays. Using fish as a vertebrate model organism tissue histological and ultrastructural observations and the stress enzyme activity were also studied. TiO2 nanoparticles (Aeroxide® P25), two phase composition of anatase (65%) and rutile (35%) with an average particle size value of 27.6±11 nm were used. Results on the EC50 for the tested aquatic organisms showed toxicity for the bacteria, the algae and the crustacean, being the algae the most sensitive tested organism. The aquatic plant Lemna minor showed no effect on growth. The fish Carassius auratus showed no effect on a 21 day survival test, though at a biochemical level the cytosolic Glutathione-S-Transferase total activity, in intestines, showed a general significant decrease (p<0.05) after 14 days of exposure for all tested concentrations. The presence of TiO2 nanoparticles aggregates were observed in the intestine lumen but their internalization by intestine cells could not be confirmed.
- Oxidative stress and histological changes following exposure to diamond nanoparticles in the freshwater Asian clam Corbicula fluminea (Müller, 1774)Publication . Cid, António; Picado, Ana; Correia, J.B.; Chaves, Rúben; Silva, Héber; Caldeira, Jorge; Matos, A. Alves de; Diniz, M. S.Recently, the scientific community became aware of the potential ability of nanoparticles to cause toxicity in living organisms. Therefore, many of the implications for aquatic ecosystems and its effects on living organisms are still to be evaluated and fully understood. In this study, the toxicity of nanodiamonds (NDs) was assessed in the freshwater bivalve (Corbicula fluminea) following exposure to different nominal concentrations of NDs (0.01, 0.1, 1, and 10 mg l-1) throughout 14 days. The NDs were characterized (gravimetry, pH, zeta potential, electron microscopy, and atomic force microscopy) confirming manufacturer information and showing NDs with a size of 4–6 nm. Oxidative stress enzymes activities (glutathione-S-transferase, catalase) and lipid peroxidation were determined. The results show a trend to increase in GST activities after seven days of exposure in bivalves exposed to NDs concentrations (>0.1 mg l-1), while for catalase a significant increase was found in bivalves exposed from 0.01 to 1.0 mg l-1 following an exposure of 14 days. The histological analysis revealed alterations in digestive gland cells, such as vacuolization and thickening. The lipid peroxidation showed a trend to increase for the different tested NDs concentrations which is compatible with the observed cellular damage.
- TiO2 nanoparticles intake by fish gill cells following exposurePublication . Diniz, M. S.; Matos, A. Alves de; Lourenço, Joana; Castro, Luísa; Peres, Isabel; Mendonça, E.; Picado, Ana