Microsystem-assisted synthesis of carbon dots with fluorescent and colorimetric properties for pH detection

The present paper describes the use of a microfluidic system to synthesize carbon dots (Cdots) and their use as optical pH sensors. The synthesis is based on the thermal decomposition of ascorbic acid in dimethyl sulfoxide. The proposed microsystem is composed of a fluidic and a thermal platform, which enable proper control of synthesis variables. Uniform and monodispersed 3.3 nm-sized Cdots have been synthesized, the optical characterization of which showed their down/upconversion luminescence and colorimetric properties. The obtained Cdots have been used for pH detection with down and upconverison fluorescent properties as excitation sources. The naked eye or a photographic digital camera has also been implemented as detection systems with the hue parameter showing a linear pH range from 3.5 to 10.2. On the other hand, experiments on the cytotoxicity and permeability of the Cdots on human embryonic kidney cells revealed their adsorption on cells without causing any impact on the cellular morphology.This work was supported by Projects SGR 2009-0323 from Catalonia Government and P10-FQM-5974 from the Junta de Andalucía (Spain). These projects were partially supported by European Regional Development Funds (ERDF). Our thanks to “Reincorporacion de Doctores UGR” programs and Greib startu

Nanoecotoxicity effects of engineered silver and gold nanoparticles in aquatic organisms

Engineered nanoparticles (ENPs) are increasingly being incorporated into commercial products. A better understanding is required of their environmental impacts in aquatic ecosystems. This review deals with the ecotoxicity effects of silver and gold ENPs (AgNPs and AuNPs) in aquatic organisms, and considers the means by which these ENPs enter aquatic environments, their aggregation status and their toxicity. Since ENPs are transported horizontally and vertically in the water column, we discuss certain factors (e.g., salinity and the presence of natural organic materials), as they cause variations in the degree of aggregation, size range and ENP toxicity. We pay special attention to oxidative stress induced in organisms by ENPs. We describe some of the main analytical methods used to determine reactive oxygen species, antioxidant enzyme activity, DNA damage, protein modifications, lipid peroxidation and relevant metabolic activities. We offer an overview of the mechanisms of action of AgNPs and AuNPs and the ways that relevant environmental factors can affect their speciation, agglomeration or aggregation, and ultimately their bio-availability to aquatic organisms. Finally, we discuss similarities and differences in the adverse effects of ENPs in freshwater and salt-water systems.The authors thank the Regional Government of Andalusia (P09-FQM-4554) and the Spanish national government [CSIC (201060E005 NPHIPER)] for financial support.Peer reviewe

Public concern over ecotoxicology risks from nanomaterials: Pressing need for research-based information

The public have been told that nanotechnology is a new and promising, albeit complex, field of scientific research, but it is a field where reliable education and clear, balanced information is increasingly needed (Wickson et al., 2010). Scientists and the general public have different perceptions of the potential risks from the use of nanotechnology (Scheufele et al., 2007). The field of potential applications that is opening up presents serious challenges for all those involved in research, government and industry to reflect the issues, positive and negative, in informative reports that are available to all citizens. Feedback from surveys shows that citizens are worried about possible adverse consequences of nanotechnology. They want reassurance that these risks are not only being communicated correctly but also that effective means of countering or minimizing them are being actively studied and adopted by the authorities. Such worries are understandable since the general public is, in effect, the last link in the chain of vulnerability, in the event of a release of dangerous nanoparticles (NPs). Some communities may not even know that they act as the ultimate “sink” for nanomaterials.Authors thank the financial support from Junta de Andalucia (P09-FQM-4554) and CSIC (201060E005 NPHIPER).Peer reviewe

Assesing toxicity of citrate-gold nanoparticles at different marine trophic levels (microalgae, copepods and bivalve mollusks)

Ponencia presentada en la NanoSpain Conference, celebrada en Santander del 27 de febrero al 1 de marzo de 2012.Engineered nanoparticles (ENPs) may offer benefits to society in general, although they sometimes inherently have unintended effects on ecosystems. As a consequence, assessment of the environmental safety of ENPs has become a major issue worldwide [1]. Within the metallic ENPs, gold nanoparticles have been used extensively in drug delivery, gene therapy, biosensing and contrast agent for imaging [2]. However, studies about the effects of gold nanoparticles are limited and they are specially focused on ¿in vitro¿ experiments rather than ¿in vivo¿ systems. Additionally, estuaries and coastal ecosystems are the final receptors of substances dumped in the environment wherefore the effects of these substances should be tested in representative site specific organisms. In order to assess the effect of gold-citrate nanoparticles on aquatic ecosystems, toxicity tests were carried out in three groups of model organisms belonging to different trophic levels: the marine microalgae species Cylindrotheca closterium, Chlorella autotrophyca, Phaeodactylum tricornutum, Pleurochrysis pseudoroscoffensis and Rhodomonas salina (Fig. 1), the copepod, Tisbe battagliai (Fig. 2) and the clam Ruditapes philippinarum (Fig. 3). The gold-citrate NPs employed were citrate reduced AuNPs in the range of 20 ¿ 30 nm, or soluble gold, H(AuCl4) as positive control. For the toxicity test with microalgae, the selected endpoint was population growth after 72 hours of exposure. The cells were incubated in batch cultures of 50 mL in artificial seawater enriched with simple medium (nitrate, phosphate, silica) and exposed under continuous light conditions at 20±1ºC to different dissolved Au or NPs concentrations. Growths of experimental populations were compared with controls, and concentrations which imply an inhibition of 50% respect the controls (EC50%) are calculated (Fig. 4). Dissolved Au toxicity ranged from 0.052 ± 0.001 mg¿L-1 for Rhodomonas salina to 0.50 ± 0.15 mg¿L-1 for Chlorella autotrophyca. Concentrations at ecologically significant values for NPs (up to 0.3 mg¿L-1) did not imply growth inhibitions over 50%. For copepods, nauplii (< 24 h-old) were exposed (48 h) to increasing concentrations of Au-NPs in 12-well plates (5 ml/well, 4 nauplii/well and 5 replicates/concentration) under the above described laboratory conditions [3]. The results are shown in Figure 5. The clam, Ruditapes philippinarum was exposed for 28 days to two Au-NPs concentrations: 6 and 30 ¿g·L-1. Clams were collected different at sampling points and target tissues (gills, digestive gland and mantel) were dissected and stored at -80ºC until their analysis. No significant mortality was recorded during the experiment and bioaccumulation in the digestive gland along the experiment was measured (Figure 6). In summary, no acute toxicity was recorded at ecological relevant concentrations for assayed Au-NPs. Nevertheless, further research should be necessary to know the effect of chronic exposure to these NPs and to improve the knowledge about their environmental risk assessment.Peer Reviewe

Bioensayos de toxicidad para AU disuelto y para nanopartículas de Au-Citrato sobre cinco especies microalgales marinas

Trabajo presentado en el XVI Seminario Ibérico de Química Marina, celebrado en Cádiz del 24 al 26 de enero de 2012.La fabricación de nanopartículas (NPs) ha ido incrementándose en los últimos años, debido a su uso en numerosas aplicaciones (cosmética, biomedicina, catálisis, etc.). Sin embargo, la toxicidad de estos materiales es ampliamente desconocida para los organismos acuáticos y, especialmente, para los organismos marinos. Así, en este trabajo se ha llevado a cabo una primera aproximación sobre el efecto tóxico de las NPs de oro-citrato en microalgas marinas, organismos pertenecientes a un eslabón trófico clave en ecosistemas marinos y estuáricos. Se calcularon los valores de EC5Q tanto para el oro disuelto como para NPs de oro-citrato. Los valores de EC50 para oro disuelto fueron (mg L -1) de 0.50 ± 0.15 para Cylindrotheca closterium; de 0.10 ± 0.01 para Chlorella autotrophyca; de 0.078 ± 0.013 para Phaeodactylum tricornutum; de 0.11 ± 0.01 para Pleurochrysis pseudoroscojJensis y de 0.052 ± O.OOlpara Rhodomonas salina. En ensayos utilizando Au-NPs no se alcanzaron valores del 50 % de inhibición aún a concentraciones medioambientalmente no relevantes (0.3 mg L - 1). La mayor sensibilidad relativa al oro disuelto (y a las Au-NPs) de Rhodomonas salina puede deberse a su estructura celular, que implica una mayor exposición de la membrana plasmática (situada sobre la pared celular proteica) en comparación con otras clases microalgales, cuyas membranas plasmáticas están protegidas por paredes de celulosa, sílice o carbonato cálcico. Estos resultados parecen indicar que la toxicidad para las micro algas estaría asociada al oro disuelto, aunque sería necesario realizar estudios pormenorizados sobre la posible permeación de las células a las NPs, la interiorización de las mismas y los mecanismos de protección celularPeer Reviewe

Effects of the exposure of the clam Ruditapes philippinarum to gold nanoparticles. Evaluation of enzymatic and molecular endpoints

Trabajo presentado en el PRIMO 16 (Pollutant Responses in Marine Organisms), celebrado en Long Beach (California, USA) del 15 al 18 de mayo de 2011.Nanoparticles (NPs) are introduced into a growing number of commercial products, eventually leading to their release into the different environmental compartments (air, soil and surface waters). Up today, ecotoxicological risks i n non target organisms associated with NPs are poorly documented. Thus in this study, the marine bivalve Ruditapes philippinarum was chosen as ecotoxicological model to evaluate the enzymatic and molecular biomarkers of effects of exposure to gold nanopart icles (AuNPs). The organisms were exposed in the laboratory to gold added to natural filtered seawater either in the form of citrate reduced AuNPs (approximately 6 and 30 μg·L - 1 ) in the range of 20 – 30 nm or as soluble gold, H(AuCl 4 ) (50 μg·L - 1 ) for 28 da ys. Samples (digestive gland, gills and mantle) were taken throughout the exposure period in order to monitor the development of the expression of the chosen endpoints over time. Au concentrations and biomarkers of oxidative stress (catalase, GST, SOD, lip id peroxidation) were quantified in the three tissues. Metallothionein levels as a biomarker of metal exposure was evaluated both by HPLC and PCR approach. Additionally, different features involved in the inflammatory response, known to be induced by NPs i n other organisms, were monitored by quantitative real time PCR. Sections of gill and digestive gland tissue were observed under electron microscope (TEM/SEM) coupled to microanalysis (EDX). Our results show that exposure to AuNPs significantly alters the activity of the tested enzymes and also produces changes in the expression of metallothionein as well as of different, inflammation related features tested by PT - PCR.Peer Reviewe

Enzymatic and molecular responses on the Manila clan, Ruditapes philippinarujm to gold nanoparticles . Evaluation of enzymatic and molecular endpoints

Trabajo presentado en la 6th International Conference on the Environmental Effects of Nanoparticles and Nanomaterials, celebrada en Londres del 19 al 21 de noviembre de 2011.Nanoparticles (NPs) are introduced into a growing number of commercial products, eventually leading to their release into the different environmental compartments. Up today, ecotoxicological risks in non target organisms associated with NPs are poorly documented. Thus in this study, the marine bivalve Ruditapes philippinarum was chosen as ecotoxicological model to evaluate the enzymatic and molecular biomarkers of effects of exposure to gold nanoparticles (AuNPs). The organisms were exposed in the laboratory to gold added to natural filtered seawater either in the form of citrale reduced AuNPs (approximately 6 and 30 ~g'L-1) in Ihe range of 20 - 30 nm or as soluble gold, H(AuCI4) (50 ~g'L-1) for 28 days. Samples (digestive gland, gills and mantle) were taken throughoul the exposure period in order to monitor. The development of Ihe expression of the chosen endpoints over time. Au concentrations were analysed in the three tissues. Biomarkers of oxidative stress (calalase, GPX, SOO, lipid peroxidalion) were quantified in digestive gland and gills. Metallothionein levels were evaluated by different approaches (HPLC and real time PCR). Additionally, different features involved in the inflammatory response, known to be induced by NPs in other organisms, were monitored by quantitative real time PCR Sections of gill and digestive gland tissue were observed under electron microscope (TEM/SEM) coupled to micro analysis (EOX). Our results show that exposure to AuNPs does not alter significantly the response of the selected biomarkers of oxidative stress in a clear way. However, dissolved gold showed lo alter the response of these endpoints.Peer Reviewe

Behaviour of Au-citrate nanoparticles in seawater and accumulation in bivalves at environmentally relevant concentrations

8 páginas, 1 tabla, 5 figurasThe degree of aggregation and/or coalescence of Au-citrate nanoparticles (AuNPs, mean size 21.5 ± 2.9 nm), after delivery in simulated seawater, are shown to be concentration-dependent. At low concentrations no coalescence and only limited aggregation of primary particles were found. Experiments were performed in which the marine bivalve (Ruditapes philippinarum) was exposed to AuNPs or dissolved Au and subsequently, bivalve tissues were studied by Scanning and Transmission Electron Microscopy and chemical analyses. We show that the bivalve accumulates gold in both cases within either the digestive gland or gill tissues, in different concentrations (including values of predicted environmental relevance). After 28 days of exposure, electron-dense deposits (corresponding to AuNPs, as proven by X-ray microanalysis) were observed in the heterolysosomes of the digestive gland cells. Although non-measurable solubility of AuNPs in seawater was found, evidence is presented of the toxicity produced by Au3+ dissolved species (chloroauric acid solutions) and its relevance is discussed.The authors gratefully acknowledge financial support from the Junta de Andalucía (FEDER PE2009-FQM-4554, TEP-217) and EU FP7 AL-NANOFUNC project (CT-REGPOT2011-1-285895). We would like to thank A. Fernández-Estefane of CITIUS for the preparation of TEM samples. We also thank ICMS and CITIUS for Electron Microscopy facilities.Peer reviewe

Toxicity of silver and gold-silver alloy nanoparticles in marine and freshwater microalgae

Trabajo presentado en el XVII Seminario Ibérico de Química Marina (evento que une al IV Congreso de Ciencias del Mar, IV Simposio Internacional de Ciencias del Mar y al Encuentro de la Oceanografía Física), celebrado en Las Palmas de Gran Canaria del 11 al 13 de junio de 2014.The development of the nanotechnology has promoted the use of metal nanoparticles (MNPs) and nano-materials (NMs) for a wide range of areas and applications. In the daily life are being extensively used inhousehold products (cosmetics or sunscreens) or in industrial uses (paints, catalysts, coatings, packagingmaterial, electronics, etc.). Since the NMs are in continuous growth, the emerging market is estimates toexceed one trillion dollars by 2015 (DEFRA, 2007).Nanoparticles (NPs) occurrence in the environment might cause adverse effects over the ecosystemshealth and consequently, these effects need to be assessed. Ecotoxicological methods should be de-veloped in order to assess the NPs risks. Their effect over life is largely influenced not only by theirinteraction with the surrounded aquatic media but also by the physico-chemical properties of the NPs.In aquatic media, the NPs mostly tend to be dissolved in their ions or to suffer different aggregations,which largely determines its toxicity. The extent of this aggregation mainly is dependent on the surfacecharge, particles morphology (shape and size), pH and the ionic strength of the medium. In seawater theincreasing salinity, and therefore ionic strength, reduces the negativity of electrophoretic mobility of theparticles to encourage aggregation (Batley et al., 2013).Most studies have been conducted with freshwater species such asDaphnia magna(Lovern and Kapler,2006) andPimephales promelas(Zhu et al., 2006). Unfortunately, in spite of the high importance intothe trophic structure of ecosystems, just a few marine species and photosynthetic organisms (Navarro etal., 2008) have been checked in these kind of studies.Traditionally, gold nanoparticles (AuNPs) have been widely considered as non-toxic particles althoughtheir potential toxicity has not been fully assessed, yet. On the opposite, the toxicity of the silver nanopar-ticles (AgNPs) has raised an increasing attention. Some of the most important factors related to thetoxicity of both types of NPs are the oxidative stress and the effect on DNA, lipids and certain metabolicactivities (Lapresta-Fernandez et al., 2012). Therefore, an ecotoxicity study was carried out for some living species in the presence of AgNPs,dissolved silver (Agdis) and silver-gold alloy nanoparticles (AuAgNPs). Interestingly, by modifyingthe NPs composition, the toxicity of the NPs can be fine-tuned. In order to assess the toxicity ofAgNPs and Agdis, a 72 hours exposure testing growth inhibition was performed over two marine di-atoms species (Phaeodactylum tricornutumandCylindrotheca closterium) and two freshwater microal-gae species (Chlamydomonas reinhardtiiandNitzschia palea). Moreover, AuAgNPs toxicity responseswere studied inP. tricornutumandN. palea.The results show AgNPs toxicity (in terms of EC50) is smaller with Agdis for all species tested. HigherEC50 is also observed in marine species.N. paleais the most sensitive species (EC50Agdis = 0.081±0.017μM and EC50AgNP = 0.707±0.198μM); whileC. closteriumis the most resistant species(EC50Agdis = 0.043±1.074μM and EC50AgNP = 2.219±0.159μM). In the case of AuAgNPs, theEC50 values found for the random species studied are 3.286±1.217μM for N. palea and 0.990±0.231μM forP. tricornutum.N