Browsing by Author "Fraga, S."
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- In vitro acute toxicity of metal-based nanoparticles in human trophoblast BeWo b30 cellsPublication . Pires, J.; Moreira, L.; Teixeira, J.P.; Fraga, S.Metal nanoparticles (M-NP) are among the most widely used nanomaterials in consumer products available in the market. Thus, human exposure to these nanosized materials is increasing, which raises serious concerns regarding their environmental and human safety. Biological barriers are important lines of defence to xenobiotics, thus expected targets for M-NP. In this regard, special consideration must be given to the placenta that acts as barrier between maternal and the developing fetus. The present study aimed at evaluating in vitro toxicity of different M-NP in a human cell model of placental barrier: trophoblastic (BeWo clone b30) epithelial cells. BeWo b30 cells were exposed for 24 h to varied concentrations (0.8–48 µg/cm2) of M-NP of different chemical composition (Au, Ag and TiO2), primary size (10, 30 and 60 nm), capping (citrate and PEG) and crystal structure (rutile and anatase).
- In vitro toxicity of metal nanoparticles in two human barrier models: role of the physicochemical featuresPublication . Pires, J; Moreira, L; Teixeira, J.P.; Fraga, S.Metal nanoparticles (M-NP) are among the most widely used nanomaterials in consumer products available in the market. Thus, human exposure to these nanosized materials is increasing, which raises serious concerns regarding their environmental and human safety. Biological barriers are important lines of defence to xenobiotics, thus expected targets for M-NP. The present study aimed at evaluating the in vitro toxicity of different M-NPs in two cell models of biological barriers: human intestinal (Caco-2) and trophoblastic (BeWo clone b30) epithelial cells. Cells were exposed for 24 h to varied concentrations (0.8-48 µg/cm2) of M-NP of different chemical composition (Au, Ag, TiO2), primary size (10, 30 and 60 nm), capping (citrate, PEG) and crystal structure (rutile, anatase) and toxicity assessed by determining changes in cell morphology, metabolic activity, plasma membrane integrity, generation of intracellular reactive oxygen species (ROS) and intracellular ATP levels. Our data show that the toxicity potential of the tested M-NP is similar in both cell lines with AgNPs > AuNPs > TiO2 NPs, being the effects more visible at higher concentrations. The influence of the size in the cytotoxic-induced effects was more evident for AgNP than for AuNP, with the smaller NP causing more toxicity, being the BeWo cells more sensitive to these M-NP. In addition, PEG-capping effectively attenuated AuNP-induced toxicity in both barrier models. In addition, only cells exposed to AgNP exhibited significant increased levels of ROS. Thus, our data support that the physicochemical properties of M-NP are an important determinant of their cytotoxicity and that intestinal and trophoblastic cells exhibit different sensitivity to the tested M-NP. Future studies would be useful to further explore the effects of M-NP in the human barriers.
- Influence of the surface coating on the cytotoxicity, genotoxicity and uptake of gold nanoparticles in human HepG2 cellsPublication . Fraga, S.; Faria, H.; Soares, M.E.; Duarte, J.A.; Soares, L.; Pereira, E.; Costa-Pereira, C.; Teixeira, João Paulo; de Lourdes Bastos, M.; Carmo, H.The toxicological profile of gold nanoparticles (AuNPs) remains controversial. Significant efforts to develop surface coatings to improve biocompatibility have been carried out. In vivo biodistribution studies have shown that the liver is a target for AuNPs accumulation. Therefore, we investigated the effects induced by ~20 nm spherical AuNPs (0-200 μM Au) with two surface coatings, citrate (Cit) compared with 11-mercaptoundecanoic acid (11-MUA), in human liver HepG2 cells. Cytotoxicity was evaluated using the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) reduction and lactate dehydrogenase (LDH) release assays after 24 to 72 h of incubation. DNA damage was assessed by the comet assay, 24 h after incubation with the capped AuNPs. Uptake and subcellular distribution of the tested AuNPs was evaluated by quantifying the gold intracellular content by graphite furnace atomic absorption spectrometry (GFAAS) and transmission electron microscopy (TEM), respectively. The obtained results indicate that both differently coated AuNPs did not induce significant cytotoxicity. An inverse concentration-dependent increase in comet tail intensity and tail moment was observed in Cit-AuNPs- but not in MUA-AuNPs-exposed cells. Both AuNPs were internalized in a concentration-dependent manner. However, no differences were found in the extent of the internalization between the two types of NPs. Electron-dense deposits of agglomerates of Cit- and MUA-AuNPs were observed either inside endosomes or in the intercellular spaces. In spite of the absence of cytotoxicity, DNA damage was observed after exposure to the lower concentrations of Cit- but not to MUA-AuNPs. Thus, our data supports the importance of the surface properties to increase the biocompatibility and safety of AuNPs.
- Insights into corrosion behaviour of uncoated Mg alloys for biomedical applications in different aqueous mediaPublication . Neves, C.S.; Sousa, I.; Freitas, M.A.; Moreira, L.; Costa, C.; Teixeira, J.P.; Fraga, S.; Pinto, E.; Almeida, A.; Scharnagl, N.; Zheludkevich, M.L.; Ferreira, M.G.S.; Tedim, J.MgCa and MgGd series of alloys are often reported as promising candidates for biomedical applications. In the present study, cytotoxicity and corrosion behavior of Mg1Ca and Mg10Gd alloys in different electrolytes (NaCl, PBS, MEM) have been investigated in order to make a direct comparison and understand the mechanisms behind their performance. Potentiodynamic polarization and electrochemical impedance spectroscopy (EIS) were employed to analyze corrosion processes depending on media composition, whereas X-Ray diffraction (XRD) and scanning electron microscopy (SEM) were used to evaluate crystalline structure, phase composition and surface morphology of the corroded substrates after immersion in the different electrolytes. Moreover, cytotoxicity of the Mg alloys was assessed using the WST-1 reduction and lactate dehydrogenase (LDH) release assays in L929 mouse fibroblasts. The electrochemical results showed that Mg1Ca has a lower degradation rate when compared to Mg10Gd, due to the lower microgalvanic effects and the presence of Ca as an alloying element. Furthermore, the corrosion activity is reduced in MEM, for both alloys, when compared to NaCl and PBS. The cytotoxicity assays revealed that Mg10Gd was cytotoxic in all the conditions tested, while the toxicity of Mg1Ca was low. Overall, these findings show that Mg1Ca alloy presents a higher corrosion resistance and biocompatibility and is a promising material to be used in biomedical implants.
- Insights into the role of the physicochemical properties in the toxicity of SiO2 nanoparticles in rat alveolar epithelial RLE-6TN cellsPublication . Brandão, M.F.P.; Bessa, M.J.; Costa, C.; Fraga, S.; Haase, A.; Teixeira, J.P.Silica nanoparticles (SiO2 NPs) are easily produced in different sizes and surface modifications enabling their use in several industrial and biomedical applications, which increases the risk of human exposure to these nanoparticles. Because the toxicological profile of nanoparticles is dependent upon their physicochemical properties, the aim of this study was to investigate the influence of the physicochemical properties (size, surface capping and hydrophilicity/hydrophobicity) in the cyto- and genotoxicity of SiO2 NPs in rat alveolar epithelial cells (RLE-6TN), a primary target during inhalation exposure.
- Safe production and use of nanomaterials in the ceramic industry: the CERASAFE projectPublication . Viana, M.; Querol, X.; Alastuey, A.; Fonseca, A.S.; de la Fuente, G.F.; Estepa, C.; Monfort, E.; López-Lilao, A.; Ibáñez, M.J.; Gomes, J.; Albuquerque, P.; Esteves, H.; Miranda, R.M.; Teixeira, J.; Fraga, S.; Simon, S.; Bychkov, E; Biskos, G.The ceramic industry is a growing industrial sector, which is benefitting from advances made available through nanotechnology and a number of innovative industrial processes. However, production of nanomaterials, including the manufacture and use of nanoceramics, cannot be considered safe without a thorough investigation regarding exposure and toxicity of nanoceramic materials, which is a current research gap. This requires better knowledge of workers’ exposure in the ceramic sector and during nanoceramics manufacturing, handling and processing, which will firstly require the understanding of exposure scenarios. In this framework, the ERANET-SIINN project CERASAFE aims to assess and improve environmental health and safety (EHS) in the ceramic industry. The objective of this project is to study industrial processes and activities which may generate nanoparticle emissions into workplace air, and to assess worker exposure by evaluating the particle release processes, characterizing the emitted particles, and understanding their toxicity.
- Toxicity of gold nanorods on zebrafish (Danio rerio) embryosPublication . Mesquita, B.; Fraga, S.; Simões, A.M.; Lopes, I.; Teixeira, J.P.Gold nanoparticles (NPs) are being incorporated into various consumer products and are very promising in biomedicine as diagnostic and therapeutic delivery platforms. However, concerns about their safety, environmental and health impact have risen, as they might establish harmful interactions with biological systems. In this context, it is of major importance to understand the implications of exposure to these NPs on early life stages of biota, which have been considered, in general, as the most sensitive to chemical contamination. The present study aimed to evaluate the lethal and sublethal effects that gold nanorods (GNRs) may provoke on early-life stages of the fish species Danio rerio.
- Toxicity of gold nanorods on zebrafish (Danio rerio) embryosPublication . Mesquita, B.S.; Fraga, S.; Simões, A.M.; Lopes, I.; Teixeira, J.P.Introduction: Gold nanoparticles (NPs) are being incorporated into various consumer products and are very promising in biomedicine as diagnostic and therapeutic delivery platforms. However, concerns about their safety, environmental and health impact have risen, as they might establish harmful interactions with biological systems. In this context, it is of major importance to understand the implications of exposure to these NPs on early life stages of biota, which have been considered, in general, as the most sensitive to chemical contamination. Objective: The present study aimed to evaluate the lethal and sublethal effects that gold nanorods (GNRs) may provoke on earlylife stages of the fish species Danio rerio.
- Utility of salivary leucocytes for biomonitoring of human exposure to nanomaterials by means of the comet assayPublication . Valdiglesias, Vanessa; Fernández-Bertólez, Natália; Touzani, A.; Mendéz, J.; Martinez, L.; Pásaro, E.; Reis, A.T.; Fraga, S.; Teixeira, J.P.; Costa, C.; Laffon, B.Metal-based nanoparticles (NP) are being increasingly used in a wide variety of applications in consumer products and biomedical practices. As a result, human exposure to these nanomaterials is frequent, becoming a concern to public health. Human salivary leucocytes have been proposed as a proper biological sample for the comet assay, becoming an adequate non-invasive alternative model to evaluate DNA damage. In the present study, the suitability of salivary leucocytes to respond to exposure to different nanomaterials was addressed.
- Viability assay and DNA double strand break induction in nervous system cells exposed to cerium dioxide nanoparticlesPublication . Fernandez-Bertolez, N.; Touzani, A.; Martinez, L.; Méndez, J.; Ramos-Paz, L.; Reis, A.T.; Fraga, S.; Costa, C.; Teixeira, J.P.; Pásaro, E.; Valdiglesias, V.; Laffon, B.Cerium dioxide nanoparticles (CeO2 NP) show antioxidant enzyme mimetic properties and free radical scavenging activity. These properties make them a promising material for biomedical applications, but their potential adverse effects are not totally understood yet. Our objective was to assess the biological behaviour of CeO2 NP in human neuronal and glial cells. After carrying out the physical-chemical characterization of the CeO2 NP and analysing their ability to be taken up by neuronal and glial cells, the possible alterations in cell viability and induction of DNA double strand breaks were determined by means of MTT assay and γH2AX assay, respectively. The possible existence of interference of the NP with the assay methodologies was previously addressed and corrected when necessary. The results obtained showed that, even though there was a significant dose- and time-dependent internalization of the NP by both cell lines, the CeO2 NP generally presented scarce cyto- or genotoxicity, essentially depending on the NP exposure time and being restricted to higher doses. These results provide a better understanding of the interaction of CeO2 NP with cellular systems and their possible adverse effects, specifically at nervous system level.