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Toxicity of Nanoparticles of CuO, ZnO and TiO2 to Microalgae Pseudokirchneriella subcapitata
Abstract
Toxicities of ZnO, TiO2 and CuO nanoparticles to Pseudokirchneriella subcapitata were determined using OECD 201 algal growth inhibition test taking in account potential shading of light. The results showed that the shading effect by nanoparticles was negligible. ZnO nanoparticles were most toxic followed by nano CuO and nano TiO2. The toxicities of bulk and nano ZnO particles were both similar to that of ZnSO4 (72 h EC50 approximately 0.04 mg Zn/l). Thus, in this low concentration range the toxicity was attributed solely to solubilized Zn2+ ions. Bulk TiO2 (EC50=35.9 mg Ti/l) and bulk CuO (EC50=11.55 mg Cu/l) were less toxic than their nano formulations (EC50=5.83 mg Ti/l and 0.71 mg Cu/l). NOEC (no-observed-effect-concentrations) that may be used for risk assessment purposes for bulk and nano ZnO did not differ (approximately 0.02 mg Zn/l). NOEC for nano CuO was 0.42 mg Cu/l and for bulk CuO 8.03 mg Cu/l. For nano TiO2 the NOEC was 0.98 mg Ti/l and for bulk TiO2 10.1 mg Ti/l. Nano TiO2 formed characteristic aggregates entrapping algal cells that may contribute to the toxic effect of nano TiO2 to algae. At 72 h EC50 values of nano CuO and CuO, 25% of copper from nano CuO was bioavailable and only 0.18% of copper from bulk CuO. Thus, according to recombinant bacterial and yeast Cu-sensors, copper from nano CuO was 141-fold more bioavailable than from bulk CuO. Also, toxic effects of Cu oxides to algae were due to bioavailable copper ions. To our knowledge, this is one of the first systematic studies on effects of metal oxide nanoparticles on algal growth and the first describing toxic effects of nano CuO towards algae.
... 60 μg/L which indicates a comparable toxicity. These findings are consistent with the observation of Aruoja et al. (2009). ...
... By measuring the effective toxic dose, CuO NPs and Cu bulk were 0.94 mg/L and 0.37 mg/L, respectively, unveiling a stronger phototoxicity of Cu bulk. Contradictorily, as opposite to CuO bulk, CuO NPs has more pronounced toxicity as a result of its copper bioavailability was 141 fold than that of CuO bulk (Aruoja et al., 2009). Similar results were also confirmed in algae tests (Dolenc Koce, 2017). ...
... It was observed that the aggregation behaviour of TiO 2 NPs was more intensive and tighter than that of TiO 2 bulk in P. subcapitata (Aruoja et al., 2009). Distinct with the previously described MNPs, the toxicity mechanism of TiO 2 NPs does not appear to be due to the released Ti ions, but resulted from their aggregation behaviour, which impeded the algae growth and photosynthesis by decreased the light availability. ...
This review presents a comprehensive analysis of the ecological implications of metallic nanoparticles (MNPs) on photosynthetic organisms, particularly plants and algae. We delve into the toxicological impacts of various MNPs, including gold, silver, copper-based, zinc oxide, and titanium dioxide nanoparticles, elucidating their effects on the growth and health of these organisms. The article also summarizes the toxicity mechanisms of these nanoparticles in plants and algae from previous research, providing insight into the cellular and molecular interactions that underpin these effects. Furthermore, it discusses the reciprocal interactions between different types of MNPs, their combined effects with other metal contaminants, and compares the toxicity between MNPs with their counterpart. This review highlights the urgent need for a deeper understanding of the environmental impact, considering their escalating use and the potential risks they pose to ecological systems, especially in the context of photosynthetic organisms that are vital to ecosystem health and stability.
... These shortage issues severely limit the widespread use of TiO2 in photo-catalysis [27,68,69]. However, there are substantial restrictions on nanomaterials' applications in consideration of their impacts on humans and the environment due to their employment [70,71]. ...
... Photo-catalysts are generally difficult to recycle; because of the high-cost requirements, separating TiO2 catalyst from the solution after treatment may pose a barrier to their use in the disposal of industrial wastewater [45,54,70,222]. ...
... However, there are substantial constraints to the usage of nanomaterials in terms of the consequences on human health and ecosystems due to their use [70,71]. ...
The immobilization of titanium dioxide (TiO2), a prominent photo-catalyst, on various substrates has received a lot of interest over the last two decades since it avoids the need for costly post-treatment separation methods. Among the many substrates tested for supporting TiO2 photo-catalysts, polymer substrate appears to be the most promising due to multiple advantages such as its flexible nature, low cost, chemical resistance, mechanical stability, low density, high durability, and ease of availability. The proximity of photo-catalysis and the support system significantly increased the transfer step between adsorption and the total oxidative decolorization process. A comparison of photodecolorization with many synthetic dyes was made, and it was found that the structural and surface features of the photo-catalyst influenced the photocatalytic activities. This review focuses on TiO2-PMMA nanocomposites and thoroughly investigates the synthesis, photocatalytic activity, and reuse of TiO 2 /PMMA photo-catalysts. Finally, the future study scope and commercialization problems of PMMA-supported TiO2 photo-catalysts in visible and/or solar light have been highlighted.
... The acute toxicity of ZnO nanoparticles (L(E)C 50 : 0.05-1000 mg l −1 ) and CuO nanoparticles (E(L)C 50 : 0.05-569 mg l −1 ) was already documented for bacteria, algae, protozoa, nematoda, crustacea, and fish. [42][43][44][45][46][47][48][49][50][51] In this regard, it is also important to understand the toxic effects of these NPs on algae-bacteria consortia. ...
... Fig. 6 shows the % of ions released in the algae-bacteria consortia due to the exposure to single and a mixture of nanoparticles in the present study. Firstly, the mode of action of these two NPs to E. coli may be such that when acting 44 The toxicities of bulk and nanosized CuO were strongly influenced by soluble Cu ions. ZnO NPs inhibited alga P. subcapitata growth. ...
The present study investigated the effect of single as well as mixture of nanoparticles (ZnO and CuO NPs) on algae-bacteria consortia using the OECD 96-h toxicity test, one of the first efforts as per the authors’ knowledge. Scenedesmus obliquus (microalgae) and bacteria (Escherichia coli) were used as test organisms in OECD media. Effects of the different concentrations of NPs (0, 0.1 mg/L, 1 mg/L, 10 mg/L, and 100 mg/L) on 3 algae-bacteria ratios (1:1, 1:100 and 100:1) were studied using parameters, such as chlorophyll content, biomass, lipid, protein content, reactive oxygen species (ROS) generation, and extracellular polymeric substance (EPS) components. At environmentally relevant NP concentration (0.1 mg/L), the order of toxicity of NPs to algae-bacteria consortia was found to be: CuO NPs (highest toxicity)>ZnO+CuO NPs>ZnO NPs (least toxicity). At 100 mg/L NP concentration, structural changes and cell leakage in the samples containing NPs with algae-bacteria consortia were observed during TEM analysis. FTIR (Fourier Transform infra-red) analysis indicated the addition of bonds and a difference in the peak location and its intensity values. The corresponding metal ions (Zn and Cu ions) resulted in higher toxicity to algae-bacteria consortia than that from metal oxide NPs. When nanoparticles were interacting in the algae-bacteria consortia in the suspension, it was observed that by absorption and dissolution, nanoparticles would enter inside the algal and bacterial cell simultaneously, altering the surface charge of the cell membrane. Due to the formation of EPS, some of the nanoparticles would not be able to enter the cell cytoplasm but would interact with the EPS. ROS generation would be taking place extracellular as well as intracellular due to the interaction of nanoparticles. Overall, the mixture of NPs at environmentally relevant concentrations (<1mg/L) poses lesser toxicity to algae-bacteria consortia than individual nanoparticles. Further work is required to understand the effect on the functioning of algae-bacteria consortia so that a mixture of NPs containing wastewater can be used for sustaining algae-bacteria consortia for wastewater treatment.
... The Clavier et al. (2019) study reported that the presence of divalent and trivalent cations may strongly modify the NP properties by decreasing the effective charge on NP and improving the condensation state around the nanoparticle. Earlier, studies have shown that NPs release their corresponding ions which also pose toxicity to algae (Aruoja et al. 2009;Zhu et al. 2020). This possibility of binding of zinc and copper ions to algae cells was also observed in this study as well. ...
... The FTIR analysis support this aspect as ions only can bind with algae cell wall as per observed bonds with zinc and copper in the FTIR spectrum ( Supplementary Fig. F.1a-e). The binding of ions with algae (i.e., Zn ions-algae or Cu ions-algae) (Aruoja et al. 2009;Xue et al. 1990)) or bonding of NPs to algae cells (Sadiq et al. 2011;Suman et al. 2015;Pakrashi et al. 2013) has also been observed previously. As higher amount of Cu ions (80.12%) was observed to release in suspension containing mixture of NPs than that due to one type of NPs, it might have resulted in higher aggregation of particles near algal cells (TEM images, Appendix G) and subsequently higher toxicity to cells also. ...
The present study investigated the possible toxic effect of ZnO and CuO nanoparticles (NPs) on freshwater microalgae, Scenedesmus obliquus at environmentally- relevant nanoparticle concentration (1 mg/L) and high concentration (10 mg/L) in BG-11 medium under white light LED-illumination over 35 days. The effect of time on the stability of media, nanoparticles, and their relation to toxicity to algae was also studied. The transmission electron microscopy indicated structural damage to algae due to the presence of a mixture of nanoparticles (at 10 mg/L). FTIR (Fourier Transform infrared) analysis of a sample containing a mixture of nanoparticles showed an addition of bonds and a difference in the peak location and its intensity values. The inhibition time for biomass was observed between 14 days and 21 days at 10 mg/L NPs. At 1 mg/L, the order of toxicity of NPs to algae was found to be: CuO NPs (highest toxicity) > ZnO NPs>ZnO + CuO NPs (least toxicity). During exposure of algae cells to a mixture of NPs at 10 mg/L NP concentration, a smaller value of metal deposition was observed than that during exposure to individual NPs. Antagonistic toxic effects of two NPs on dry cell weight of algae was observed at both concentration levels. Future work is needed to understand the steps involved in toxicity due to mixture of NPs to algae so that environmental exposures of algae to NPs can be managed and minimized.
... 63 Similar results were obtained by other studies showing that the solubilization of CuO-NP is one reason for their toxicity. 30,64,65 Additionally, the sediment could act as a sink for CuO-NP and furthermore have negative effects on, for example, the abundance and bioaccumulation of sediment dwelling organisms like Gastrotricha (e.g., Chaetonotus), Annelida (e.g., Lumbriculus), and Mollusca (e.g., Lymnea, Physella). 3,6,54,66,67 In this process, CuO-NP can be transformed more slowly and in a different ration to organic Cu-sulfides and NOM-Cu bound copper compared to added ions (e.g., Cu(NO 3 ) 2 ) resulting in different fate processes. ...
... Dissolved Cu is toxic to algae (Culicidae diet), thus reducing the food availability to Culicidae. 30,89 This, in turn, could have caused longer developmental times under competition, predation, and food deficiency than in the control treatment. The presence of predators and competitors resulted for example in a longer development time for Anopheles larvae. ...
Transformation, dissolution, and sorption of copper oxide nanoparticles (CuO-NP) play an important role in freshwater ecosystems. We present the first mesocosm experiment on the fate of CuO-NP and the dynamics of the zooplankton community over a period of 12 months. Increasingly low (0.08-0.28 mg Cu L-1) and high (0.99-2.99 mg Cu L-1) concentrations of CuO-NP and CuSO4 (0.10-0.34 mg Cu L-1) were tested in a multiple dosing scenario. At the high applied concentration (CuO-NP_H) CuO-NP aggregated and sank onto the sediment layer, where we recovered 63% of Cu applied. For the low concentration (CuO-NP_L) only 41% of applied copper could be recovered in the sediment. In the water column, the percentage of initially applied Cu recovered was on average 3-fold higher for CuO-NP_L than for CuO-NP_H. Zooplankton abundance was substantially compromised in the treatments CuSO4 (p < 0.001) and CuO-NP_L (p < 0.001). Community analysis indicated that Cladocera were most affected (bk = -0.49), followed by Nematocera (bk = -0.32). The abundance of Cladocera over time and of Dixidae in summer was significantly reduced in the treatment CuO-NP_L (p < 0.001; p < 0.05) compared to the Control. Our results indicate a higher potential for negative impacts on the freshwater community when lower concentrations of CuO-NP (<0.1 mg Cu L-1) enter the ecosystem.
... The existence of nanoparticles, specifically those made of metals, may harm a number of fish physiological functions. Reproductive hormone levels may be disrupted antioxidant and enzyme activity can change, the survival of embryonic developmental stages may be impacted, and histopathological changes are possible (Aruoja et al. 2009;Jovanović et al. 2015;Klingelfus et al. 2019;Kumar et al. 2017;Rajkumar et al. 2016;Ren et al. 2018;Sumi and Chitra 2019;Zhu et al. 2012). There are still a lot of outstanding concerns about the possible toxicity of using nanotechnology in aquaculture, causing a need for further study in this particular field. ...
The application of nanotechnology is significantly revolutionizing the domain of fisheries. Nanotechnology tools are applied to tackle many challenges pertaining to fish productivity, health, reproduction, prevention and treatment of diseases. Fish growth performance can be improved by adding essential minerals in the form of nano-feed supplements. Moreover, nanotechnology is currently assuming a pivotal position in the domain of fish reproduction, alongside its application in fish medicine, including antibacterial therapies, medication delivery mechanisms, and nano-vaccination. Also, there are significant evidences supporting the use of nanotechnology techniques for fish packing and water purification and remediation. In contrast, numerous nanoparticles possess harmful characteristics towards living organisms as a result of their tiny sizes, potent reactivity, and capacity to cross boundaries. They have the ability to modify several physiological activities and induce cytotoxicity, DNA damage, and histopathological alterations. Although nanotechnology has potential for enhancing growth performance and disease resistance in fish, there is ongoing debate about the potential toxicity of nanomaterials, their interactions with the environment, and their propensity to accumulate in animals. This review aims to clarify and analyze the different benefits and challenges associated with the application of nanotechnology in fish farming.
... 8,9 In the past decades, considerable measures including physical, biological, and chemical methods have been carried out all over the world for HABs control. [10][11][12][13][14] For instance, the chemical methods such as aluminum and ferric sulfate coagulants, functional nanomaterials (Ce 2 O 3 , TiO 2 , CuO, ZnO, and iron-based nanoparticles, etc.) have been used for microalgae (including cyanobacteria and algae) removal 2,3,7,[15][16][17][18][19][20][21][22] ; various chemical oxidants (H 2 O 2 , O 3 , Cl 2 , CaO 2 , and permanganate) have also been proposed to deal with the microalgae. [23][24][25] However, the oxidants mentioned above may cause the lysis of cyanobacterial cells and the release of IOM, and resulting in the potential formation of DBPs. ...
As advanced oxidation processes (AOPs) is considered to be a highly effective approach for degrading organic pollutants, the simultaneous coagulation and oxidation process by the Fenton‐like reaction of nanoscale zero‐valent iron (NZVI) and hydrogen peroxide (H2O2) is investigated to eliminate the harmful cyanobacterium Microcystis aeruginosa in this study, and the process conditions are optimized using the central composite design of response surface methodology (RSM); in addition, the removal efficiency of M. aeruginosa (in terms of chlorophyll a, Chl a) and the verifications of the antioxidant abilities, as well as extracellular organic matters (EOM) and intracellular organic matters (IOM) are investigated under the optimized conditions. Results indicate that H2O2 concentration is the key factor affecting the Chl a removal efficiency, and the maximum Chl a removal reaches 98.10% under the optimized conditions: NZVI concentration 62.82 mg L⁻¹, H2O2 concentration 54.2 mmol L⁻¹, pH 4.38 and rotating speed 67 rpm. The high correlation coefficient (R² > 0.80) of analysis of variance (ANOVA) demonstrates the RSM model is extremely significant and suitable for experimental results. Moreover, the total organic carbon (TOC) and fluorescent substances (soluble cyanobacteria metabolic byproducts, aromatic proteins II, humic and fulvic acid‐like compounds) for both EOM and IOM are enhanced removal. It is speculated the removal mechanisms of the Fenton‐like process of NZVI/H2O2 for cyanobacterium belongs to the combined actions of the oxidation of Fe(II)/H2O2 and the coagulation of Fe(III), which destroy the defense system and result in the removal of M. aeruginosa.
... The observed impact of SS3 could be due to the mixture of different inorganic UV filters (non-nano TiO 2 and ZnO) (de la Vega et al., 2019), which might determine an increase in the reactive oxygen species levels (Sánchez-Quiles and Tovar-Sánchez, 2014) compared to those generated by a single inorganic UV filter. In addition, embryo malformations observed following SS3 exposure, have been linked to the concentration of Zn ions internalized (Cunningham et al., 2020;Aruoja et al., 2009) due to the rapid solubility of Zn 2+ ions in seawater (Xiong et al., 2011). ...
Although the negative effects of inorganic UV filters have been documented on several marine organisms,sunscreen products containing such filters are available in the market and proposed as eco-friendly substitutes forharmful, and already banned, organic UV filters (e.g. octinoxate and oxybenzone). In the present study, weinvestigated the effects of four sunscreen products, labelled by cosmetic companies as “eco-friendly”, on the earlydevelopmental stages of the sea urchin Paracentrotus lividus, a keystone species occurring in vulnerable coastalhabitats. Among sunscreens tested, those containing ZnO and TiO2 or their mix caused severe impacts on seaurchin embryos. We show that inorganic UV filters were incorporated by larvae during their development and,despite the activation of defence strategies (e.g. phagocytosis by coelomocytes), generated anomalies such asskeletal malformations and tissue necrosis. Conversely, the sunscreen product containing only new-generationorganic UV filters (e.g. methylene bis-benzotriazolyl tetramethyl, ethylhexyl triazone, butylphenol dieth-ylamino hydroxybenzoyl hexyl benzoate) did not affect sea urchins, thus resulting actually eco-compatible. Ourfindings expand information on the impact of inorganic UV filters on marine life, corroborate the need toimprove the eco-friendliness assessment of sunscreen products and warn of the risk of bioaccumulation andpotential biomagnification of inorganic UV filters along the marine food chain.
... 28 The concentrations used for this study were chosen based on previous toxicity studies which indicate that 5 mg L −1 of metals can cause oxidative stress and affect bacterial growth. 29,30 An additional three experimental conditions were tested to investigate the impacts of dissolved metal species. All conditions were tested in triplicate. ...
Antibiotic resistance is a public health crisis. Antibiotic resistant bacteria (ARB) and antibiotic resistance genes (ARGs) are present in drinking water distribution systems. Metals are known selective pressures for antibiotic resistance, and metallic corrosion products are found within drinking water distribution systems due to the corrosion of metal pipes. While corrosion products are a source of metals, the impact of specific corrosion products on antibiotic resistance has not been investigated. The objective of this study was to determine the impact of six corrosion products—CuO, Cu2O, Pb5(PO4)3OH, β-PbO2, Fe3O4, and α-FeOOH—on the abundance of ARB and ARGs. Lab-scale microcosms were seeded with source water from Lake Michigan and amended with individual corrosion products. In general, copper and lead corrosion products increased antibiotic resistance, although not universally across different ARB and ARG types. Concentration and speciation of copper and lead corrosion products were found to have an impact on antibiotic resistance profiles. Meanwhile, iron corrosion products had minimal impact on antibiotic resistance. Overall, this study sheds light on how pipe materials may impact antibiotic resistance as a result of corrosion products.
... Therefore, ZnWO 4 -NPs presented very low free ions release (≈0.4% of Zn 2+ ) when compared to other metal-tungstates such as α-Ag 2 WO 4 , which released free silver (Ag + ) up to ≈ 30% of their total amount (Abreu et al., 2022b). Comparing to literature, Zn and ZnO-NPs presented IC-50 values on R. subcapitata of, respectively, 0.03 and 0.04 mg Zn L − 1 (Aruoja et al., 2009;Gebara et al., 2020), far more toxic than ZnWO 4 -NPs. ...
Nanoparticles have applications in many sectors in the society. ZnWO4 nanoparticles (ZnWO4-NPs) have potential in the fabrication of sensors, lasers, and batteries, and in environmental remediation. Thus, these NPs may reach aquatic ecosystems. However, we still do not know their effects on aquatic biota and, to our knowledge, this is the first study that evaluates the toxicity of ZnWO4-NPs in a eukaryotic organism. We evaluated the toxicity of ZnWO4-NPs on the green microalga Raphidocelis subcapitata for 96 h, in terms of growth, cell parameters, photosynthesis, and biochemical analysis. Results show that most of Zn was presented in its particulate form, with low amounts of Zn2+, resulting in toxicity at higher levels. The growth was affected from 8.4 mg L−1, with 96h–IC–50 of 23.34 mg L−1. The chlorophyll a (Chl a) content increased at 30.2 mg L−1, while the fluorescence of Chl a (FL3-H) decreased at 15.2 mg L−1. We observed increased ROS levels at 44.4 mg L−1. Regarding photosynthesis, the NPs affected the oxygen evolving complex (OEC) and the efficiency of the photosystem II at 22.9 mg L−1. At 44.4 mg L−1 the qP decreased, indicating closure of reaction centers, probably affecting carbon assimilation, which explains the decay of carbohydrates. There was a decrease of qN (non-regulated energy dissipation, not used in photosynthesis), NPQ (regulated energy dissipation) and Y(NPQ) (regulated energy dissipation via heat), indicating damage to the photoprotection system; and an increase in Y(NO), which is the non-regulated energy dissipation via heat and fluorescence. Therefore, to protect aquatic ecosystems, it is extremely important to study the toxicity of emerging contaminants on microalgae, as they are at the base of aquatic food chains, and impacts on these primary producers can affect entire ecosystems. Our study shows that ZnWO4-NPs affect the growth and physiological and biochemical parameters of the chlorophycean R. subcapitata.
... This indicated that Cu and Cd share the same cellular pathway and binding site for the given microalga. In 72 h exposure against Cu, Ti, and Zn in Pseudokirchneriella subcapitata [82], the CuO EC50 value for growth was noted as being the highest, but toxicity on ZnO was highest for algal cells (pigments). The high sensitivity to ZnO and CuO of the algae was attributed to soluble metal ions that are released from the metal oxide particles in the culture medium. ...
Several types of contaminants are anthropogenically introduced into natural aquatic ecosystems and interact with other chemicals and/or with living organisms. Although metal toxicity alone has been relatively well studied, the toxic metal ion effects in the mixture have been thoroughly studied only during the last decades. This review focuses on the published reciprocal effects of different metals on different species of algae, together with describing their toxic effects on studied parameters. Phytoplankton as a bioindicator can help to estimate the reciprocal metal risk factor. Many methodologies have been developed and explored, such as the biotic ligand model (BLM), concentration addition (CA), independent action (IA), sensitivity distribution of EC50 species sensitivity distribution (SSD curves), and others, to study reciprocal metal toxicity and provide promising results, which are briefly mentioned too. From our review, we can commonly conclude the following: Zn acted antagonistically with most heavy metals (Al, Cu, Cd, and Ni). The Cu interaction with Cd, Fe, and Pb was mostly antagonistic. Cd showed synergistic behaviour with Hg, Cu, Zn, and Pb and antagonistic behaviour with Co and Fe in many cases. Methods and techniques need to be developed and optimised to determine reciprocal metal toxicity so that the ecotoxicological predictions made by using phytoplankton can be more accurate and related to real-time toxic metals risks to the aquatic ecosystem. This is the main objective of ecotoxicological tests for risk assessment. Understanding how metals enter algal cells and organelles can help to solve this challenge and was one of the main parts of the review.
... The toxicity of some other nanomaterials, such as carbon nanotubes, Fe 2 O 3 nanoparticles and MgO nanoparticles was also reported for various green algae. For instance, MgO nanoparticle was found to be toxic to S. obliquus and Pseudokirchneriella subcapitata even at low (0.8 mg/L) and high concentrations (100 mg/L), respectively 26,27 . Different sensitivity of algal species to various concentrations of nanomaterials was also observed for iron-based nanoparticles. ...
Layered double hydroxides (LDHs), regarding their physical and structural properties, have different and wide applications industry and their increasing use may raise ecological and human health concerns. However, the potential toxicity mechanisms of LDHs in different organisms are still unclear. In the present work, after synthesizing of ZnFe-SO4 LDH and studying of its characterization by XRD, FT-IR, SEM, EDX-mapping, TEM and Raman, its toxicity in Tetradesmus obliquus was evaluated. According to experimental results, the growth of the algae and content of photosynthetic pigments were significantly decreased after treatment with 100 mg/L of ZnFe-SO4 LDH. The high dose exposure to the LDH also inhibited the activity of SOD and POD enzymes, possibly due to the LDH- catalyzed reactive oxygen species production. In addition, lipid peroxidation and the content of phenolic compounds, as no-enzymatic antioxidants were increased by enhancement of the LDH concentration. The rise of phenol, flavonoids and MDA contents could be regarded as some manifestations and responses to the toxic effects of the contaminant in the algae cells. The results provided a better understanding of the undesirable effects and toxicity of LDHs in aquatic organisms.
... The wide application of nanomaterials or their technology causes the emission of engineered nanoparticles discharged into aquatic ecosystems. Entrapping nanotitanium dioxide of algal cells plays an important role, leading to ecotoxicity to algae Pseudokirchneriella subcapitata (Aruoja et al. 2009). In particular, nanoparticles (1-100 nm) can transport pollutants and alter their mobility, toxicity, transformation, and bioavailability (Besha et al. ...
Algae play a vital role in aquatic ecosystems, contributing to oxygen production and serving as a foundational component of the food chain. Environment stress and contamination can lead to harmful algal blooms, depleting oxygen levels and creating dead zones in water bodies. When exposed to contaminants such as industrial chemicals, pharmaceuticals, pesticides, heavy metals, and synthetic nano/microparticles, algae can exhibit adverse responses, disrupting the balance of aquatic ecosystems. Furthermore, environmental issues related to ecotoxicology responses of algae include the disruption of biodiversity and the loss of crucial habitats, which can lead to health issues. We reviewed the response of algae exposed to contaminants in the aquatic environments, including ecotoxicology and environmental stresses. The major points are: (1) The accumulation of polycyclic aromatic hydrocarbons in food chains and ecosystems and their uptake is widely revealed as a major concern for environmental health and human beings. (2) Bisphenol A can negatively impact algae by inhibiting biochemical and physiological processes, in which half maximal effective concentration varies from 1.0 mg L-1 to 100 mg L-1. (3) Though the level of per- and polyfluoroalkyl substances in the environment is generally low, ranging from ng L-1 to mg L-1, the combined contaminant exposure leads to significantly more significant toxic effects than individual compounds. (4) An exposure level of 1000ng L is unsafe for the ecosystems, and per- and polyfluoroalkyl substances could lead to algal growth inhibition, e.g., damage to the photosynthetic, inhibition of deoxyribonucleic acid replication, and reactive oxygen species metabolism. (5) The ecotoxicity of chemicals to algae is influenced by chemical, biological, and physical factors, creating complex effects at the biological community level. (6) This research indicated the importance of the ecotoxicology response of algae to contaminants, emphasizing the necessity for monitoring and strategic interventions to protect the sustainability of aquatic ecosystems.
... Microalgae can act as bio-indicators of pollution when ENPs are introduced into the marine environment (Gambardella et al., 2018;Zhang et al., 2018a;Zhu et al., 2020). The effect of ENPs on microalgae is usually assessed by parameters of population lethal effects, such as growth rate, chlorophyll fluorescence and oxidative stress (Aruoja et al., 2009;Dalai et al., 2013;Ma et al., 2013;Zhu et al., 2022). ...
... Magnetite was toxic to algae, with an EC 50 value of 2.2 mg/L; however, the composite containing magnetite core was not harmful to algae. In contrast to our previous studies [2][3][4], TiO 2 did not inhibit algal growth at 100 mg/L and the entrapment of algal cells within TiO 2 aggregates was not witnessed. According to our results, the organic polymers as well as the TiO 2 produced within this study are not environmentally harmful, while the toxicity of ZnO has to be considered when designing nanocomposites. ...
... In the marine media, none of the tested materials was ecotoxic to P. tricornutum according to what was seen in growth inhibition percentages ( Figure 8) and in the 72 h-EC50 values (Table 3). However, ZnO NPs already demonstrated an ecotoxic potential in previous studies with P. subcapitata (freshwater algae): a 72 h-EC50 of 0.042 mg/L [30] or 0.049 mg/L [31]. Both studies attributed the toxicity to the solubilized Zn 2+ ions. ...
Micro(nano)plastics (MNPs) can be generated from a variety of sources, including the breakdown of larger plastic items, the abrasion of synthetic textiles, and the fragmentation of plastic waste. These particles can become airborne and be transported by wind, potentially leading to their presence in the atmosphere. Due to their widespread applications, ZnO particles at the nanometer range have attractive proprieties that make them appropriate for being combined with polymers, especially PET (polyethylene terephthalate), the most commonly used polymer in the packaging sector. Nevertheless, ZnO NPs have a potential ecotoxicity that could be reflected in PET-ZnO composites reaching the environment in the form of micro(nano)plastics. To assess the potential release of PET-ZnO, as well as the ecotoxicity of ZnO NPs, PET-ZnO and weathered composites were analyzed. The ecotoxicity of PET-ZnO was tested in organisms representing different food-chain levels and compared to ZnO NPs’ ecotoxicity. The composite form contained a stable dispersion of around 3.7% of NPs uniformly scattered in the polymeric matrix. ZnO NPs were toxic to Vibrio fischeri and Brachionus calyciflorus. PET-ZnO did not exhibited any toxicity to the organisms studied, while a moderate level of toxicity was observed for the weathered forms.
... ZnO NPs inhibited alga P. subcapitata growth (Franklin et al. 2007). CuO NPs toxicity on the algae Pseduokirchneriella subcapitata was studied using the bulk formulation of metal oxide as a control (Aruoja et al. 2009). CuO NPs (EC 50 = 0.71 mg Cu/L) were found to be more soluble and toxic than the control sample at low concentrations (EC 50 = 11.55 mg Cu/L). ...
The possible impact of ZnO and CuO nanoparticles (NPs) (individually and in binary mixture) was investigated using the freshwater microalgae, Scenedesmus obliquus. The present study shows the effect of nanoparticles on algae in OECD growth media, wastewater, and pond water during a 96-h toxicity test. At 0.1 mg/L concentration of the mixture of NPs, the reduction in the chlorophyll a content was 13.61±1.34% (OECD media), 28.83±1.85% (wastewater), and 31.81±2.23% (pond water). Values of reduction in biomass were observed to be 42.13±1.38%, 39.96±1.03%, and 33.10±1.29% for OECD media, wastewater, and pond water, respectively. The highest increase in lipid values was observed in the case of pond water (6.3±1.31%). A significant increase in the value of EPS-generated protein was observed in the wastewater sample. EPS-generated carbohydrate values were increased in OECD media but decreased in the wastewater matrix. The transmission electron microscope images showed structural damage to algae cells due to the exposure to a mixture of nanoparticles at higher concentrations. Fourier transform infrared analysis showed an addition of bonds and differences in the peak and its intensity during exposure to high concentrations of NPs. Overall, this study gives fundamental insights into the interaction and toxicity of a mixture of NPs to algal species in different water matrices.
... By exploiting the unique fluorescence properties of silver nanoclusters (AgNCs) along with various other analytical/biological tools, Zhang et al. (2017) reported that the photosynthetic toxicity of AgNCs was largely attributed to adverse effect of particulate form of Ag + , which resulted in the disruption of the electron transport chain of light reaction and stimulated the key enzymes (carboxylase/oxygenase) of Calvin cycle of algae cells. Another toxicity mechanism of NPs in microalgae is the formation of large number of aggregates by interaction with the cell wall or adsorb onto the external cell surface, which resulted in the impairment cell division with consequent decrease on growth rate (Aruoja, Dubourguier, Kasemets, & Kahru, 2009;Ji et al., 2011;Handy et al., 2012;Oukarroum et al., 2012). In Daphnia, the toxic effects of AgNPs may depend on the AgNPs concentration accumulated in Daphnia organs (Ribeiro et al., 2017). ...
Silver nanoparticles (AgNPs) have been widely used to produce consumer goods that vary in type and application. Undoubtedly the increase of production and consumption of these silver-containing products has led to the entry of silver compounds into the aquatic system. In this study, we used tropical groups of aquatic organisms including the freshwater green algae Scenedesmus acuminatus, the marine diatom Chaetoceros gracilis and the microcrustacean Daphnia lumholtzi as model organisms to investigate the acute and chronic toxicity of AgNPs. The test organisms were exposed following specific and standardized protocols for each species/endpoints, with modifications when necessary. The endpoints recorded were growth inhibition, survival, growth of parent animals and number of live neonates produced. The EC50 values of AgNP for the growth inhibition of S. acuminatus and C. graciliswere 38.5 μg/L and 24.3 μg/L, respectively. The values of median lethal concentrations (24h-and 48 h-LC50) of AgNPs to D. lumholtzi were 69.3 and 57.6 μg/L. In the chronic exposure, tested animals were exposed to AgNP from 0.1 to 5 μg/L for 21 days. Chronic effects of AgNP on survival, growth and reproduction of the microcrustacean D. lumholtzi were observed in concentrations higher than 0.5 μg/L.
... The adsorption of AgNPs on the surface of microalgae cells will induce obvious toxicity through direct or indirect physical reactions, such as the disintegration of cell walls [40], or the reduction in light required for algal growth ("shading effect") [41], and limit the utilization of nutrients [42,43]. In the study by Burchardt et al. [36], the same concentration of AgNPs also exhibited varying degrees of growth inhibition on Pseudomonas aeruginosa (inhibition percentage: from 40% to 60%) and Polycystis cyanobacteria (inhibition percentage: 100%). ...
With the rapid development of nanotechnology, nanomaterials have been widely utilized in many industries and daily life applications due to their unique properties. However, their potential release and the human health/environmental consequences have raised public concern greatly. In this study, we compared the toxic effects of AgNPs and AgNO3 on Skeletonema costatum in 10, 100, and 500 μg·L−1 Ag treatments. In all the AgNP exposure experiments, cell membrane damage and growth inhibition occurred. However, the cellular damage only obviously appears on exposure to a high concentration of AgNO3. The antioxidant enzyme (SOD and CAT) activities and lipid peroxidation in Skeletonema costatum were also induced significantly in the AgNP treatments. In addition, the percentage of Ag release in seawater increased with the increase in AgNP concentrations (13%, 32% for 100 and 500 μg·L−1 AgNPs). Thus, the biotoxic effects of AgNPs were found to be due to a combination of the solubilization of particles into toxic metal ions and the nature of the nanoparticles. It was worth noting that the induction of oxidative stress and damage to the cell membrane comprised the dominant mechanism of toxicity for AgNPs. Therefore, the behavior of nanometals in seawater affects the biotoxic effect on the phytoplankton. These results shed light on the biological toxicity of nanometals and their possible toxicity mechanism.
... In general, TiO 2 is considered as both an inert and safe nanomaterial, despite some controversial issue about the biotoxicity of titanium dioxide nanoparticles has been recently raised [26,27]. Neurotoxicity from TiO 2 , at least in experimental animals, has been observed for concentrations as low as 2.5 mg/kg body weight (bulk TiO 2 ) [28], despite the EC 50 of TiO 2 nanosized formulation is around 5.83 mg/L [29]. However, toxicological tests on S. cerevisiae showed no titanium nanoparticulate toxicity even at 20,000 mg/L [30]. ...
... It absorbs UV radiation and shows self-cleaning ability. Nanoparticles have a susceptibility to adsorb other substances to form a mixture leading to a shift of toxicity to living organisms [4]. Hence, many studies have reported cytotoxic characteristics of TiO 2 [5,6]. ...
Nanoparticles with their unique features have attracted researchers over the past decades. Heavy metals, upon release and emission, may interact with different environmental components, which may lead to co-exposure to living organisms. Nanoscale titanium dioxide (nano-TiO 2 ) can adsorb heavy metals. The current idea is that nanoparticles (NPs) may act as carriers and facilitate the entry of heavy metals into organisms. Thus, the present study reports nanoscale quantitative structure–activity relationship (nano-QSAR) models, which are based on an ensemble learning approach, for predicting the cytotoxicity of heavy metals adsorbed on nano-TiO 2 to human renal cortex proximal tubule epithelial (HK-2) cells. The ensemble learning approach implements gradient boosting and bagging algorithms; that is, random forest, AdaBoost, Gradient Boost, and Extreme Gradient Boost were constructed and utilized to establish statistically significant relationships between the structural properties of NPs and the cause of cytotoxicity. To demonstrate the predictive ability of the developed nano-QSAR models, simple periodic table descriptors requiring low computational resources were utilized. The nano-QSAR models generated good R ² values (0.99–0.89), Q ² values (0.64–0.77), and Q ² F 1 values (0.99–0.71). Thus, the present work manifests that ML in conjunction with periodic table descriptors can be used to explore the features and predict unknown compounds with similar properties.
... TiO 2 exhibits lower toxicity than other nano metal oxides. The toxic effects of nanosized TiO 2 resulted from trapping cells rather than from the dissolution of metal ions (Aruoja et al., 2009). The toxicity level of TiO 2 NPs can be lowered by using the material without altering the viability of cells. ...
Diversified nanosystems with tunable physicochemical attributes have emerged as potential solution to globally devastating cancer by offering novel possibilities for improving the techniques of cancer detection, imaging, therapies, diagnosis, drug delivery and treatment. Drug delivery systems based on nanoparticles (NPs) with ability of crossing different biological barriers are becoming increasingly popular. Besides, NPs are utilized in pharmaceutical sciences to mitigate the toxicity of conventional cancer therapeutics. However, significant NPs-associated toxicity, off-targeted activities, and low biocompatibility limit their utilization for cancer theranostics and can be hazardous to cancer patients up to life-threatening conditions. NPs interact with the biomolecules and disturb their regular function by aggregating inside cells and forming a protein corona, and the formulation turns ineffective in controlling cancer cell growth. The adverse interactions between NPs and biological entities can lead to life-threatening toxicities. This review focuses on the widespread use of various NPs including zinc oxide, titanium oxide, silver, and gold, which serve as efficient nano-vehicles and demonstrate notable pharmacokinetic and pharmacodynamic advantages in cancer therapy. Subsequently, the mechanism of nanotoxicity attached with these NPs, alternate solutions and their prospect to revolutionize cancer theranostics are highlighted. This review will serve as guide for future developments associated with high-performance NPs with controlled toxicity for establishing them as modern-age nanotools to manage cancer in tailored manner.
Bivalves is a stream aquatic macro-invertebrates which can collect and concentrate pollutants even if present in low quantities. The aim of this research was to use freshwater bivalves (Coelatura aegyptiaca) as a bio-indicator for Zinc-Oxide chitosan nanoparticles (ZnO-CS NPs) in the freshwater environment. Following the preparation and characterization of ZnO-CS NPs using a UV–vis spectrophotometer, X-ray diffraction (XRD) , transmission electron microscopy (TEM), and an oxidative stress study, animals were exposed to three different doses of ZnO and ZnO-CS NPs (12.5, 25, and 50 mg/L) for a total of seven consecutive days. The ZnO-CS particles ranged in size from 4-7 nm. The nominal concentrations of ZnO-CS NPs were 12.5, 25, and 50 mg ZnO, respectively. MDA and NO levels were substantially increased in all organs in most doses of ZnO-CS NPs, while GSH and CAT levels were dramatically reduced in all organs. Histological examination of the gills, mantle, hepatopancreas (digestive gland) and foot tissues revealed alteration after exposure to ZnO-CS NPs at doses greater than 25 mg/L. The current research established that exposure to ZnO-CS NPs induced oxidative stress responses and histological alterations in Coelatura aegyptiaca organs. These physiological and histological alterations seen after exposure to ZnO-CS NPs were most likely caused by the ZnO particles themselves, since chitosan had a minimal impact on these changes. We found that Coelatura aegyptiaca was a reliable bio-indicator for assessing zinc oxide nanoparticles contaminated water.
Introduction: The rapid development of nanotechnologies with their widespread prosperities has advanced concerns regarding potential health hazards of the Nanoparticles. Results: Nanoparticles are currently present in several consumer products, including medications, food, textiles, sports equipment, and electrical components. Despite the advantages of Nanoparticles, their potential toxicity has negative impact on human health, particularly on reproductive health. Conclusions: The impact of various NPs on reproductive system function is yet to be determined. Additional research is required to study the potential toxicity of various Nanoparticles on reproductive health. The primary objective of this review is to unravel the toxic effects of different Nanoparticles on the human reproductive functions and recent investigations on the reproductive toxicity of Nanoparticles both in vitro and in vivo.
This study explores the potential of four types of nanoparticles (ZnO, ZnS, FeS2, and SnO2) to combat resistant microbes using the well method. The research focuses on their antifungal and antibacterial properties. Results showed that FeS2 and ZnO nanoparticles displayed broad-spectrum activity against various bacteria and fungi. This was evident by the formation of clear inhibition zones after 24 hours at 37°C. These findings highlight the promise of FeS2 and ZnO nanoparticles as weapons against resistant microbes. The inhibition zones demonstrate a measurable effect on microbial growth, providing valuable groundwork for further development of novel strategies to fight and manage microbial infections. This research adds to the ongoing search for alternative and effective solutions in the face of growing microbial resistance.
Comparative assessment of stress responses of two microalgal species differing in their cell structure and habitats, Prorocentrum cordatum and Dunaliella salina, to the presence of copper oxide nanoparticles (NP) in the medium was carried out. The nanoparticles were found to have a similar effect on both species. Their toxic effect resulted in progressing production of reactive oxygen species in the algal cells, while their specific growth rates decreased, probably due to Cu2+ release from the oxide or to penetration of some nanoparticles into the cells. NP mechanical impact resulted in their aggregation at the cell surface and deformation of the cell envelopes. The presence in the toxicant in the medium caused a reliable increase in cell volume, plasmalemma perforation, and predominance of deformed cells of irregular shape in the cultures. Two species exhibited different resistance to CuO NP. The sublethal and lethal concentrations for P. cordatum were 400 and 520 µg/L, respectively, compared to 3000 and 3750 µg/L for D. salina. The possible causes for resistance of D. salina to CuO NP are discussed. D. salina is able to produce ligands (phytochelatins and metallothionenis) in high concentrations, which may be released into the medium and bind the Cu2+ ions. Moreover, the habitats of D. salina are extreme, which may promote its stress tolerance, probably a genetically determined feature and a part of their overall resistance to other contaminants. High resistance of D. salina to CuO NP may also be due to its ability to secrete extracellular polymers under stress conditions; they may form a protective layer preventing the interaction between the microalgae and NP. Application of P. cordatum for biomonitoring of NP-contaminated seawater environments is proposed. D. salina may be promising for water bioremediation.
As a result of the runoff losses of agrochemicals that have been used in excessive amounts over the last few decades from agricultural soils, the levels of these harmful chemicals have
also increased in the aquatic ecosystem, where adverse impact on non-target organisms has been observed. The advantage of using nanoagrochemicals compared to conventional ones is that to achieve the same biological effect, a quantitatively smaller amount of active ingredient can be used, and when using encapsulation of the active agent or its adsorption on a suitable nanocarrier, its controlled prolonged release can be achieved, which at the same time reduces the adverse impact on the environment. Nanoagrochemicals are also generally less toxic than the conventional agrochemicals, however some of them can be more toxic to aquatic flora and fauna even at sublethal concentrations. This chapter provides a comprehensive overview of the toxic effects of nanoscale formulations of organic pesticides, carbon nanomaterials (graphene, graphene oxide, reduced graphene oxide, and carbon nanotubes), nanoscale macronutrients and Cu, Zn, and Fe-based micronutrients, as well as silver and silica
nanoparticles on algae and cyanobacteria, macrophytes and aquatic animals (mainly crustaceans, snails, bivalves, amphibians or fishes), and the relevant mechanisms of actions are discussed as well.
Nanotechnology is a cutting-edge, multidisciplinary field that encompasses a vast array of fundamental and applied sciences for the creation and use of nanoscale materials for novel solutions. However, nanoparticles (NPs) have garnered significant attention due to their widespread applications in various industries. However, their release into aquatic ecosystems has raised concerns about potential adverse effects on aquatic organisms. Nanoparticles, due to their unique properties, can enter water bodies and interact with aquatic organisms, potentially disrupting their physiology, metabolism, and growth. This can lead to ecological imbalances, affecting aquatic species and ecosystems, and necessitates thorough assessment to understand potential risks and mitigate harmful impacts. Given the findings of several ecotoxicological studies documenting their negative consequences, there is growing concern today regarding synthetic nanomaterials. This chapter explores the adverse effects nanoparticles can have on aquatic ecosystems, their exposure routes in aquatic systems and entry routes into aquatic organisms, their toxicity mechanisms, environmental conditions that affect their activities, and the ecological imbalances they result in. To mitigate the potential for ecological imbalances, it is essential to understand the risks associated with nanoparticle pollution and implement measures to minimize their release and exposure in aquatic environments.
Aim
Exploitation of nano-based materials has increased the disposal of nanoparticles into the environment. Toxic nanomaterials pose their adverse effects and severely impact the human and environmental health. The aim of this study was to explore the toxic effects of chemically-synthesized copper oxide nanoparticles (CuO-NPs) on Chlorella vulgaris using an algal growth inhibition assay.
Materials and Methods
Nanoparticles were synthesized using cupric sulfate and sodium hydroxide. Synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy (FTIR), ultraviolet-visible (UV-vis) spectroscopy, X-ray diffraction (XRD), and transmission electron microscopy. C . vulgaris culture was exposed to various concentrations of CuO-NPs at intervals of 3, 6, 12, and 24 h. Growth inhibition assay of algal culture was estimated via the spectroscopic method and cell enumeration was done by Neubauer hemocytometry.
Results
The average diameter of CuO-NPs was ~35.85 nm. UV-Vis spectroscopy was used to confirm the configuration of CuO-NPs. Therefore, FTIR results has indicated high purity of synthesized CuO-NPs. Size of the CuO-NPs was determined by XRD. Results showed that growth of C . vulgaris microalgae was notably affected by the exposure of 2 mg/L CuO-NPs concentration exposure for 6 h.
Conclusion
The current work showed that CuO-NPs have significant toxic to Chlorella sp. Data analysis showed NPs have broad effects on growth of C . vulgaris and there is a correlation between nanoparticles concentration as well as their toxicity on the microalgae.
Microalgae are microorganisms of great importance for aquatic ecosystems. The investigation of their interaction with potential environmental stressors like nanoparticles (NPs) is essential in order to assess their behavior and fate in aquatic ecosystems. The scope of this work is to investigate the response and potential toxic effects of the short-term exposure of Scenedesmus rubescens microalga to zinc oxide (ZnO) NPs with various initial nitrate concentrations in the culture medium. Scenedesmus rubescens was cultivated in four different compositions of modified BG-11 with a nitrate content varying from 0 to 300 mg/L, and it was exposed to four concentrations of ZnO NPs, ranging from 0.081 to 81 mg/L. S. rubescens was found to be resilient towards ZnO NP toxicity. The results also highlight the fact that the toxic effects of ZnO NPs on microalgae are highly dependent on the species tested. The nitrate content of the medium did not affect the toxicity of ZnO NPs but had a significant impact on cell concentration, as it was observed at an initial nitrate concentration of 300 mg/L. Further investigation should focus on studying the morphological and metabolic characteristics and mechanisms contributing to this species’ resilience.
The rapid inclusion of zinc oxide nanoparticles (ZnO NPs) in nanotechnology-based products over the last decade has generated a new threat in the apprehension of the environment. The massive use of zinc nanosized products will certainly be disposed of and be released, eventually entering the aquatic ecosystem, posing severe environmental hazards. Moreover, nanosized ZnO particles owing the larger surface area per volume exhibit different chemical interactions within the aquatic ecosystem. They undergo diverse potential transformations because of their unique physiochemical properties and the feature of receiving medium. Therefore, assessment of their impact is critical not only for scavenging the present situation but also for preventing unintended environmental hazards. Algae being a primary producer of the aquatic ecosystem help assess the risk of massive NPs usage in environmental health. Because of their nutritional needs and position at the base of aquatic food webs, algal indicators exhibit relatively unique information concerning ecosystem conditions. Moreover, algae are presently the most vital part of the circular economy. Hence, it is imperative to understand the physiologic, metabolic, and morphologic changes brought by the ZnO NPs to the algal cells along with the development of the mechanism imparting toxicity mechanism. We also need to develop an appropriate scientific strategy in the innovation process to restrain the exposure of NPs at safer levels. This review provides the details of ZnO NP interaction with algae. Moreover, their impact, mechanism, and factors affecting toxicity to the algae are discussed.
Bu çalışmada tek hücreli bir alg olan Chlamydomonas reinhardtii’nin Fe2O3, TiO2, ve ZnO NPların farklı konsantrasyonlarına (Fe2O3ve TiO2 için 1.8-61.22 mg/L, ZnO için 0.39-10.48 mg/L aralığında) 24, 72 ve 120 saat süre ile maruz bırakması sonucu ortaya çıkan toksik etkilerin değerlendirilmesi amaçlandı. Bu NP konsantrasyonları ön testlere göre belirlendi. Toksisitenin ölçütü olarak, NP’lerin kullanılan her konsantrasyonu için belirtilen süre sonunda kültür ortamlarında toplam hücre sayıları, ortamdaki canlı hücre sayıları, toplam hücre kütlesi ve hücre boyularındaki değişim kullanıldı. Sonuçlar istatistiksel olarak değerlendirilmiş ve kullanılan her üç nanoparçacığın da kültürdeki toplam hücre sayısını azalttığı (Ti< Fe
Recently, there has been growing interest in nanomaterials, especially for their applications in the biomedical field. These nanomaterials possess a small size together with astonishing physicochemical properties, which makes them most suitable for therapeutic applications. Different types of nanomaterials, such as metallic, carbon-based, fluorescent, and polymer-based, have been used in tissue engineering, drug delivery, and other therapeutic applications. Despite many useful applications, nanomaterials possess some harmful effects on the human body, vegetation, and also on the environment. Nanomaterials can enter cells or tissues and organs because of their nano-size, large surface area, and better penetrability, which may cause serious health issues (inhibition of cell proliferation, cell wall damage, modification of function and morphology of organelles, oxidative stress, genotoxicity, and cell death) in living organisms including humans. In this chapter, we have aimed to provide the harmful effects of nanomaterials as per published research papers. The topics related to nanomaterial’s toxicity, mode of action and penetration of nanomaterials in the human body are discussed. We have also discussed the government regulations, ethical issues related to nanomaterials toxicity and possible health hazards.
Over the past two decades, the application of nanostructured materials in construction, such as concrete, paint, coatings, glass, renders, plasters, thermal insulation, steel, and even sensors, has become increasingly prevalent. However, previous studies and reports have raised concerns about the ecotoxicity and long-term impact of nanomaterials on human health and the environment. National and international legislation and regulations are struggling to keep up with the rapid development of nanomaterials, taking into account their unique characteristics and essential requirements for application and commercialization. This paper, based on existing standards for conventional materials and bibliometric networks of papers focused on nanomaterials, conducts a critical review and proposes relevant indicators for the application of nanomaterials in the construction sector. These indicators should be mandatory and are divided into environmental, human health, and economic perspectives, providing a risk assessment framework for applying nanomaterial-based constructive solutions oriented to environmental, social, and economic sustainability.
Nanoparticle pollution has been shown to affect various organisms. However, the effects of nanoparticles on species interactions, and the role of species traits, such as body size, in modulating these effects, are not well‐understood. We addressed this issue using competing freshwater phytoplankton species exposed to copper oxide nanoparticles. Increasing nanoparticle concentration resulted in decreased phytoplankton species growth rates and community productivity (both abundance and biomass). Importantly, we consistently found that nanoparticles had greater negative effects on species with smaller cell sizes, such that nanoparticle pollution weakened the competitive dominance of smaller species and promoted species diversity. Moreover, nanoparticles reduced the growth rate differences and competitive ability differences of competing species, while having little effect on species niche differences. Consequently, nanoparticle pollution reduced the selection effect on phytoplankton community abundance, but increased the selection effect on community biomass. Our results suggest cell size as a key functional trait to consider when predicting phytoplankton community structure and ecosystem functioning in the face of increasing nanopollution.
Nanotechnology has emerged as an area constantly expanding, affecting practically every sphere of science and daily life. It offers new product possibilities and provides promising solutions to various problems in areas including pharmaceutics, agri-nanotechnology, electronics, the food industry, environmental science, etc. Nanotechnology is believed to be a double-edged sword because it brings in new possibilities for development. Still, at the same time, it poses some severe concerns to human health and the environment. Since this field is still in its infancy, an accurate assessment of risks posed by nanotechnology is complex. Currently, the major risk associated with using nanomaterials is the lack of control over it; there is no adequate legislation to regulate nanomaterials. Some countries have established standards and regulations; however, they are not free of loopholes. This chapter discusses significant application areas of nanomaterials, their potential risks, current law employed in different countries, main problems encountered in regulation, and some aspects of ethics.
Zinc is one of the most abundant elements in the earth's crust and is widely used in the metal, rubber, chemical, paint, and agricultural industry, in addition to the usage in cosmetics ingredients, or for medical purposes. In this context, nano‐sized zinc oxide is used in personal care products, sensors, antibacterial creams, and biomedical applications. In fact, for various organisms, zinc is an essential component in the basic cellular functions. Furthermore, extracellular zinc has the potential to interact with and modulate many different synaptic targets, induce oxidative and nitrosative stress, leading to alteration in the inflammatory responses. It is normally absorbed from the intestine, and competes with Cu ²⁺ , Fe ²⁺ , and Ca ²⁺ for absorption and potentially induces copper deficiency. Consequences of zinc deficiency have been recognized for many years, however high exposure to zinc fumes, zinc compounds, and zinc nanoparticles via inhalation, ingestion, or dermal route may result in severe hematological, developmental, gastrointestinal, and nervous system toxicity. This chapter aims to summarize the knowledge on the regulations of occupational zinc exposure limits and manifestations of bulk and nano‐sized zinc toxicity.
TiO2–Ag doped nanoparticulate (TiO2–Ag–NP) adhesive photocatalytic films were used to assess the ability in dropping down the burden of indoor microbial particles. The application of an easy-to use photocatalytic adhesive film to cleanse indoor living spaces from microbial pollution, represents a novelty in the field of photocatalytic devices. Reduction was attained by photocatalysis in selected spaces, usually with overcrowding (≥ 3 individuals) in the common working daily hours, and upon indoor microclimate monitoring. TiO2–Ag doped nanoparticulate (TiO2–Ag–NP) adhesive photocatalytic films were applied within five types of living spaces, including schools and job places. The microbial pollution was assessed at time 0 (far from routine clean, ≥ 9 h) and throughout 2–4 weeks following the photocatalyst application by relative light unit (RLU) luminometry and microbial indirect assessment (colony forming units per cubic meter, CFU/m3). TiO2–Ag–NP photocatalyst reduced RLU and CFU/m3 by rates higher than 70% leading to RLU ≤ 20 and microbial presence ≤ 35 CFU/m3. The described TiO2–Ag–NP is able to reduce microbial pollution to the lowest RLU threshold (≤ 20) within 60 min in open daylight in a standardized test room of 100 m2. The correlation between RLU and CFU/m3 was positive (r = 0.5545, p < 0.05), assessing that the microbial reduction of indoor areas by the TiO2–Ag–NP adhesive film was real. Titania photocatalysts represent promising tools to ensure air cleaning and sanitization in living indoor microclimates with a low cost, feasible and straightforward approach. This approach represents an easy to handle, cost effective, feasible and efficacious approach to reduce microbial pollution in indoor spaces, by simply attaching a TiO2–Ag–NP adhesive film on the wall.
Increasing industrialization, urbanization, and global increase in population have led to the contamination of the environment with several organic and inorganic pollutants that are hazardous to the environment and human health. Therefore, it is critical to find new technologies and implement them quickly in order to address the problem of environmental contamination. Nanotechnology (NT) has emerged as a promising technology for environmental cleanup. A range of nanomaterials, such as carbon-based, inorganic, and polymeric-based substances, are used to remove pollutants from the environment. Synthetic dyes, heavy metals, pesticides, organophosphorus compounds, chlorinated organic compounds, and volatile organic compounds (VOCs) can all be successfully removed by using nanomaterials. In addition, nano-remediation is a viable substitute for removing new pollutants, like pharmaceuticals or personal care items. In addition, methods for reducing the amount of pollutants in the environment, such as the reduction of heavy metal ions by adsorption or other processes and the adsorption and photocatalytic reduction of organic pollutants, are frequently regarded as among the most effective. Nanomaterials can be used in water, soil, or air media because of the wide variety they come in and their adaptability. The use of nanoparticles (NPs) for media cleanup is briefly discussed in this book chapter. It highlights the most current advancements in the treatment of wastewater, soil, and air using metal, carbon, polymer, and silica NPs.
In this study, a low-pressure control method for an arc-submerged nanoparticle syn-thesis system (ASNSS) was proposed and developed for CuO nanoparticle fabrication. This study investigates into the rheology of CuO nanofluid having different mean particle sizes. Experi-mental results indicate that the pH value of the CuO nanofluid fabricated in this study is 6.5, which is far smaller than isoelectric point (i.e.p) of pH 10. The CuO nanofluid with larger mean particle sizes has a larger shear stress when the shear rate of different mean particle sizes are the same. Moreover, the smaller the mean particle size of the CuO nanofluid, the higher its viscosity is because of the larger the specific surface area, and the electrostatic force between particles would also be increased.
Minerals such as titanium dioxide, TiO2, and zinc oxide, ZnO, are well known active semiconductor photocatalysts used extensively in heterogeneous photocatalysis to destroy environmental pollutants that are organic in nature. They are also extensively used in sunscreen lotions as active broadband sunscreens that screen both UVB (290–320nm) and UVA (320–400nm) sunlight radiation and as high SPF makers. When so photoactivated by UV light, however, these two particular metal oxides are known to generate highly oxidizing radicals (OH and O2-) and other reactive oxygen species (ROS) such as H2O2 and singlet oxygen, 1O2, which are known to be cytotoxic and/or genotoxic. Hydroxyl (OH) radicals photogenerated from photoactive TiO2 specimens extracted from commercial sunscreen lotions [R. Dunford, A. Salinaro, L. Cai, N. Serpone, S. Horikoshi, H. Hidaka, J. Knowland, FEBS Lett. 418 (1997) 87] induce damage to DNA plasmids in vitro and to whole human skin cells in cultures. Accordingly, the titanium dioxide particle surface was modified to produce TiO2 specimens of considerably reduced photoactivity. Deactivation of TiO2 diminishes considerably, in some cases completely suppresses damage caused to DNA plasmids, to human cells, and to yeast cells compared to non-modified specimens exposed to UVB/UVA simulated solar radiation. The photostabilities of sunscreen organic active agents in neat polar and apolar solvents and in actual commercial formulations have been examined [N. Serpone, A. Salinaro, A.V. Emeline, S. Horikoshi, H. Hidaka, J. Zhao, Photochem. Photobiol. Sci. 1 (2002) 970]. With rare exceptions, the active ingredients undergo photochemical changes (in some cases form free radicals) and the sunscreen lotions lose considerable Sun protection efficacy only after a relatively short time when exposed to simulated sunlight UVB/UVA radiation, confirming the recent findings by Sayre et al. [R.M. Sayre, J.C. Dowdy, A.J. Gerwig, W.J. Shields, R.V. Lloyd, Photochem. Photobiol. 81 (2005) 452].
Protecting human skin against harmful UV-B radiation coming from the sun is currently a problem. Due to the decreased thickness of the ozone layer, a more dangerous amount of UV-B light reaches the surface of our planet. This causes increased frequency of skin diseases. Titanium dioxide (TiO2) fine particles are embedded with sunscreens into the skin to effectively attenuate UV-B radiation. This study evaluates the most appropriate size of such particles assuming they are spheres. The distribution of TiO2 particles within the skin, achieved with topically applied sunscreens, is determined experimentally by the tape-stripping technique. Computer code implementing the Monte Carlo method is used to simulate photon migration within the plain 20 µm thick horny layer matrix partially filled with nano-sized TiO2 particles. Dependences of harmful UV-B radiation of 307–311 nm absorbed by, backscattered from and transmitted through the horny layer on the concentration of TiO2 particles are obtained and analysed. As a result, particles of 62 nm are found to be the most effective in protecting skin against UV-B light.
The antibacterial behaviour of suspensions of zinc oxide nanoparticles (ZnO nanofluids) against E. Coli has been investigated. ZnO nanoparticles from two sources are used to formulate nanofluids. The effects of particle size,
concentration and the use of dispersants on the antibacterial behaviour are examined. The results show that the ZnO nanofluids
have bacteriostatic activity against E. coli. The antibacterial activity increases with increasing nanoparticle concentration and increases with decreasing particle size.
Particle concentration is observed to be more important than particle size under the conditions of this work. The results
also show that the use of two types of dispersants (Polyethylene Glycol (PEG) and Polyvinylpyrolidone (PVP)) does not affect
much the antibacterial activity of ZnO nanofluids but enhances the stability of the suspensions. SEM analyses of the bacteria
before and after treatment with ZnO nanofluids show that the presence of ZnO nanoparticles damages the membrane wall of the
bacteria. Electrochemical measurements using a model DOPC monolayer suggest some direct interaction between ZnO nanoparticles
and the bacteria membrane at high ZnO concentrations.
Nanotechnologies have become a significant priority worldwide. Several manufactured nanoparticles - particles with one dimension less than 100 nm - are increasingly used in consumer products. At nanosize range, the properties of materials differ substantially from bulk materials of the same composition, mostly due to the increased specific surface area and reactivity, which may lead to increased bioavailability and toxicity. Thus, for the assessment of sustainability of nanotechnologies, hazards of manufactured nanoparticles have to be studied. Despite all the above mentioned, the data on the potential environmental effects of nanoparticles are rare. This mini-review is summarizing the emerging information on different aspects of ecotoxicological hazard of metal oxide nanoparticles, focusing on TiO2, ZnO and CuO. Various biotests that have been successfully used for evaluation of ecotoxic properties of pollutants to invertebrates, algae and bacteria and now increasingly applied for evaluation of hazard of nanoparticles at different levels of the aquatic food-web are discussed. Knowing the benefits and potential drawbacks of these systems, a suite of tests for evaluation of environmental hazard of nanoparticles is proposed. Special attention is paid to the influence of particle solubility and to recombinant metal-sensing bacteria as powerful tools for quantification of metal bioavailability. Using recombinant metal-specific bacterial biosensors and multitrophic ecotoxicity assays in tandem will create new scientific knowledge on the respective role of ionic species and of particles in toxicity of metal oxide nanoparticles.
When titanium dioxide (TiO(2)) is irradiated with near-UV light, this semiconductor exhibits strong bactericidal activity. In this paper, we present the first evidence that the lipid peroxidation reaction is the underlying mechanism of death of Escherichia coli K-12 cells that are irradiated in the presence of the TiO(2) photocatalyst. Using production of malondialdehyde (MDA) as an index to assess cell membrane damage by lipid peroxidation, we observed that there was an exponential increase in the production of MDA, whose concentration reached 1.1 to 2.4 nmol. mg (dry weight) of cells(-1) after 30 min of illumination, and that the kinetics of this process paralleled cell death. Under these conditions, concomitant losses of 77 to 93% of the cell respiratory activity were also detected, as measured by both oxygen uptake and reduction of 2,3,5-triphenyltetrazolium chloride from succinate as the electron donor. The occurrence of lipid peroxidation and the simultaneous losses of both membrane-dependent respiratory activity and cell viability depended strictly on the presence of both light and TiO(2). We concluded that TiO(2) photocatalysis promoted peroxidation of the polyunsaturated phospholipid component of the lipid membrane initially and induced major disorder in the E. coli cell membrane. Subsequently, essential functions that rely on intact cell membrane architecture, such as respiratory activity, were lost, and cell death was inevitable.
Due to their large potential for manifold applications, the use of nanoparticles is of increasing importance. As large amounts of nanoparticles may reach the environment voluntarily or by accident, attention should be paid on the potential impacts on the environment. First studies on potential environmental effects of photocatalytic TiO2 nanoparticles have been performed on the basis of widely accepted, standardized test systems which originally had been developed for the characterization of chemicals. The methods were adapted to the special requirements of testing photocatalytic nanoparticles.
Suspensions of two different nanoparticles were illuminated to induce their photocatalytic activity. For testing, the growth inhibition test with the green alga Desmodesmus subspicatus and the immobilization test with the daphnid Daphnia magna were selected and performed following the relevant guidelines (algae: ISO 8692, OECD 201, DIN 38412-33; daphnids: ISO 6341, OECD 202, DIN 38412-30). The guidelines were adapted to meet the special requirements for testing photocatalytic nanoparticles.
The results indicate that it is principally possible to determine the ecotoxicity of nanoparticles. It was shown that nanoparticles may have ecotoxicological effects which depend on the nature of the particles. Both products tested differ in their toxicity. Product 1 shows a clear concentration-effect curve in the test with algae (EC50: 44 mg/L). It could be proven that the observed toxicity was not caused by accompanying contaminants, since the toxic effect was comparable for the cleaned and the commercially available product. For product 2, no toxic effects were determined (maximum concentration: 50 mg/L). In the tests with daphnids, toxicity was observed for both products, although the concentration effect-curves were less pronounced. The two products differed in their toxicity; moreover, there was a difference in the toxicity of illuminated and non-illuminated products.
Both products differ in size and crystalline form, so that these parameters are assumed to contribute to the different toxicities. The concentration-effect curves for daphnids, which are less-pronounced than the curves obtained for algae, may be due to the different test organisms and/or the differing test designs. The increased toxicity of pre-illuminated particles in the tests with daphnids demonstrates that the photocatalytic activity of nanoparticles lasts for a period of time.
The following conclusions can be drawn from the test results: (I) It is principally possible to determine the ecotoxicity of (photocatalytic) nanoparticles. Therefore, they can be assessed using methods comparable to the procedures applied for assessing soluble chemicals. (II) Nanoparticles may exert ecotoxicological effects, which depend on the specific nanoparticle. (III) Comparable to traditional chemicals, the ecotoxicity depends on the test organisms and their physiology. (IV) The photocatalytic activity of nanoparticles lasts for a relevant period of time. Therefore, pre-illumination may be sufficient to detect a photocatalytic activity even by using test organisms which are not suitable for application in the pre-illumination-phase.
First results are presented which indicate that the topic 'ecotoxicity and environmental effects of nanoparticles' should not be neglected. In testing photocatalytic nanoparticles, there are still many topics that need clarification or improvement, such as the cause for an observed toxicity, the improvement of the test design, the elaboration of a test battery and an assessment strategy. On the basis of optimized test systems, it will be possible to test nanoparticles systematically. If a potential risk by specific photocatalytic particles is known, a risk-benefit analysis can be performed and, if required, risk reducing measures can be taken.
Metal oxide nanoparticles are finding increasing application in various commercial products, leading to concerns for their environmental fate and potential toxicity. It is generally assumed that nanoparticles will persist as small particles in aquatic systems and that their bioavailability could be significantly greater than that of larger particles. The current study using nanoparticulate ZnO (ca. 30 nm) has shown that this is not always so. Particle characterization using transmission electron microscopy and dynamic light scattering techniques showed that particle aggregation is significant in a freshwater system, resulting in flocs ranging from several hundred nanometers to several microns. Chemical investigations using equilibrium dialysis demonstrated rapid dissolution of ZnO nanoparticles in a freshwater medium (pH 7.6), with a saturation solubility in the milligram per liter range, similar to that of bulk ZnO. Toxicity experiments using the freshwater alga Pseudokirchneriella subcapitata revealed comparable toxicity for nanoparticulate ZnO, bulk ZnO, and ZnCl2, with a 72-h IC50 value near 60 microg Zn/ L, attributable solely to dissolved zinc. Care therefore needs to be taken in toxicity testing in ascribing toxicity to nanoparticles per se when the effects may be related, at least in part, to simple solubility.
Dissolved nutrient concentrations in natural waters may at times be controlled by interactions between particulate and solution phases. Effects of Zn (0-1 ..mu..M total Zn(II)) and orthophosphate (8-12 ..mu..M total P) additions on growth indices for the chlorophyte Selenastrum capricornutum Printz were examined in a synthetic growth medium containing 50 mg literâ»Â¹ colloidal titania. Over the Zn(II) concentration range used, detrimental growth and yield effects were observed. Addition of P to a synthetic growth medium (S-3) increased stationary phase cell density, but had minimal effect on growth rate and duration of lag phase. Presence of TiOâ particles in culture media significantly reduced Zn and P dissolved fractions. Although adsorbed Zn and P were less available to Selenastrum, desorption of both solutes increased their availability. Rapid desorption of Zn(II) from TiOâ particles served in effect to buffer Zn/sup 2 +/ free ion concentration, until Zn became partitioned primarily with the algal fraction as cell concentration approached stationary phase density. Although phosphate desorption from TiOâ in nonbiological systems was negligible, Selenastrum was able to scavenge some P initially adsorbed onto TiOâ. Accurate primary productivity predictions in nature may therefore require an understanding of equilibrium and reaction rates involved in the partitioning of nutrients and toxic substances between dissolved and particulate phases.
Photocatalytic inactivation of algae, Anabaena, Microcystis and Melosira, was carried out with the TiO2-coated pyrex hollow glass beads under the illumination of UV-A light. After being irradiated with UV-A light in the presence of the TiO2-coated pyrex glass beads, Anabaena and Microcystis, known as typical cyanobacteria, lost their photosynthetic activity, and the string of Anabaena cells and the colonies of Microcystis cells were completely separated into individual spherical one. In the case of Melosira, which is a typical diatom, however, somewhat lower photocatalytic inactivation efficiency was obtained, which was believed to be due to the presence of the inorganic siliceous wall surrounding the cells of Melosira. The TiO2-coated hollow glass beads could successfully be employed for the practical application at the eutrophicated river under sunlight. More than 50% of the chlorophyll-a concentration could be reduced by the action of TiO2 photocatalysis.
This review discusses salient features of interfacial electron transfer reactions in colloidal semiconductor solutions and thin films and their application for solar light energy conversion and photocatalytic water purification. This research is interdisciplinary and is situated at the limit between colloid science, and electrochemistry, and semiconductor physics. The section on colloidal semiconductors discusses material science aspects, optical properties, electronic properties, and charge carrier reactions in colloidal semiconductor solutions. The section on nanocrystalline semiconductor electrodes discusses some basic properties and preparation procedures of nanocrystalline TiO[sub 2] films, energetics and operations of the nanoporous solar cell, observations and importance of electronic states in the band gap region, photoinduced processes in nanocrystalline semiconductor electrodes, the electric field in a nanocrystalline electrode, and kinetic rate constants in the photosensitized solar cell. 156 refs.
This work focuses on the photocatalytic performances and antibacterial activity of TiO2 and Au/TiO2 nanosystems. While the former are obtained by a sol–gel route, the latter are synthesized by an innovative hybrid RF-sputtering/sol–gel approach, followed by ex situ annealing in air up to 600 °C. Important information on nanoparticle size, shape and distribution is obtained by the combined use of glancing incidence x-ray diffraction (GIXRD) and field emission-scanning electron microscopy (FE-SEM). Subsequently, the photocatalytic performances of the obtained nanosystems in the decomposition of the azo-dye Plasmocorinth B and their antibacterial activity in the elimination of Bacillus subtilis are illustrated and discussed in comparison with films obtained from standard Degussa P25 powders. The obtained results show a significant dependence of the functional performances on the system's compositional, structural and morphological properties. In particular, the dispersion of gold nanoparticles on the TiO2 matrix has a beneficial influence on the azo-dye photodegradation, whereas the antimicrobial activity of Au/TiO2 films is retarded with respect to pure TiO2.
CuO nanocrystals with different shapes, i.e. irregular nanoparticles, nanobelts and nanoplatelets, have been synthesized by controlling a few critical synthesis parameters to explore their catalytic properties. It was found that the rate of CO oxidation on the nanoplatelets is over six times higher than that on the nanoparticles and about three times higher than that on the nanobelts at 110 °C. Based on combined characterizations, such as BET, XRD, TEM, HRTEM and CO temperature-programmed reduction, the relationship between the catalytic reactivity and the shape as well as the predominantly exposed crystal planes of the CuO nanocrystals has been discussed.
ZnO nanoparticles in the size range from 2 to 7 nm were prepared by addition of LiOH to an ethanolic zinc acetate solution. This method [Spanhel, L.; Anderson, M. A. J. Am. Chem. Soc. 1991, 113, 2826] was modified and extended at several points. The synthesis of very small ZnO nuclei was simplified. It was found that aging of particles was governed by temperature, the water content, and the presence of reaction products. Water and acetate induced considerably accelerated particle growth. Growth could almost be stopped by removal of these species ("washing"). Washing consisted of repeated precipitation of ZnO by addition of alkanes such as heptane, removal of the supernatant, and redispersion in ethanol. The aging characteristics are interpreted in terms of the concentration of dissolved Zn II species and reactions well-known in sol-gel chemistry. These findings present a better-defined and more versatile procedure for production of clean ZnO sols of readily adjustable particle size. Such sols are of particular interest for studies of electrical and optical properties of ZnO nanoparticle films. For example, films exhibiting >99% transparency in the visible region could only be obtained by deposition from a washed sol.
In this study, an effect of addition of nanoparticles into a dye-sensitized solar cells (DSCs) ionic liquid electrolyte was explored. Carbon nanotubes, other carbon nanoparticles and titanium dioxide nanoparticles were dispersed individually into a 1-ethyl-3-methylimidazolium bis(trifluoromethylsulfonyl)imide (EMIm-TFSI) ionic liquid electrolyte by grinding. It was centrifuged to form an ionic nanocomposite gel electrolyte. The dispersion of nanoparticles resulted in a substantial increase in their viscosity. Their electric conductivity increased as well. Notable effects were obtained in photocurrent density and voltage measurements of the DSC assembled with them. Energy conversion efficiency of them was significantly improved and increased compared with a DSC using a bare ionic liquid electrolyte.
The toxicity of copper is reduced due to complexation by ligands, e.g. humic acids or synthetic compounds like EDTA. Therefore, the concentration of free metal ions has been considered the main determinant of metal toxicity. This early hypothesis was tested by adding different concentrations of copper to water from the River Rhine and to a synthetic medium, supplemented with different concentrations of EDTA. Subsequently the following parameters were determined: (1) voltammetrically labile copper (differential pulse anodic stripping voltammetry), (2) fraction of copper retained on Chelex-100 columns, (3) photosynthetic rate of the alga Selenastrum capricornutum (in synthetic medium) and (4) rate of [3H]thymidine incorporation by multiplying bacteria (in river water). Addition of 5μM Cu to the medium with 5 or 10μM of EDTA inhibited algal photosynthesis, although copper was not voltammetrically detectable (<0.005 μM). Small spikes of copper (0.06-1.00μM) added to river water inhibited the multiplication of bacteria; electrochemical determination showed no detectable copper activity at the lower concentrations. Chelex-retained copper correlated well with the percentage inhibition of the two biological activities. According to calculations using the model TITRATOR copper-EDTA complexes and un-ionized salts (mainly CuCO3) were dominant copper species in synthetic solutions inhibiting photosynthesis. The GECHEQ model calculated that free copper as well as chelex-labile copper correlated well with the inhibition of bacterial growth rate. Therefore it seems that complexed copper is “biologically available” to a significant extent. Furthermore, intermediate labile copper, such as chelex-retained copper, is an appropriate measure of copper toxicity.
Irradiation of suspensions of Escherichia coli ([approximately] 10[sup 6] cells/mL) and TiO[sub 2] (anatase) with UV-visible light of wave-lengths longer than 380 nm resulted in the killing of the bacteria within minutes. Oxygen was found to be a prerequisite for the bactericidal properties of the photocatalyst. Bacterial killing was found to adhere to first-order kinetics. The rate constant was proportional to the square root of the concentration of TiO[sub 2] and proportional to the incident light intensity in the range [approximately] 180- [approximately] 1660 [mu]E s[sup [minus]1] m[sup [minus]2]. The trends in these simulated laboratory experiments were mimicked by outdoor tests conducted under the summer noonday sun in Texas. The implications of these results as well as those of previous investigations in terms of practical applicability to solar-assisted water treatment and disinfection at remote sites are discussed relative to water technologies currently considered as viable as alternatives to chlorination. 24 refs., 8 figs.
The performances of four chronic toxicity tests, comprising the Daphnia magna 21-day (d) (crustacean), Brachionus calyciflorus 2-d (rotifer), Pseudokirchneriella subcapitata 72-h (green algae), and the Microtox chronic 22-h (bacteria) tests, were compared. Sixteen chemicals with toxicity covering 6 orders of magnitude were studied. Very high correlations were found between the NOEC/EC(10) Pseudokirchneriella 72-h, NOEC/EC(10) Brachionus 2-d, and the NOEC Daphnia 21-d tests. The toxicological response of rotifers and microalgae were within the same order of magnitude as the response of Daphnia in 80% of cases (13/16 chemicals). The Microtox chronic test also anticipated the overall results of the Daphnia 21-d test, but the prediction was rather imprecise, compared with microalgae and rotifers. The test measuring the algal growth inhibition of P. subcapitata after 72h was the most sensitive bioassay. Toxicity on microalgae after 72h could be estimated after 5h by measuring either the direct fluorescence of either photosynthetic pigments or fluorescein diacetate in 56 and 43% of cases, respectively. The median value of the ratio between EC(10) and EC(50) was 3.75, 2, and 1.5 with the algae, the rotifers, and the bacteria, respectively.
The biotic ligand model (BLM) of acute metal toxicity to aquatic organisms is based on the idea that mortality occurs when the metal-biotic ligand complex reaches a critical concentration. For fish, the biotic ligand is either known or suspected to be the sodium or calcium channel proteins in the gill surface that regulate the ionic composition of the blood. For other organisms, it is hypothesized that a biotic ligand exists and that mortality can be modeled in a similar way. The biotic ligand interacts with the metal cations in solution. The amount of metal that binds is determined by a competition for metal ions between the biotic ligand and the other aqueous ligands, particularly dissolved organic matter (DOM), and the competition for the biotic ligand between the toxic metal ion and the other metal cations in solution, for example, calcium. The model is a generalization of the free ion activity model that relates toxicity to the concentration of the divalent metal cation. The difference is the presence of competitive binding at the biotic ligand, which models the protective effects of other metal cations, and the direct influence of pH. The model is implemented using the Windermere humic aqueous model (WHAM) model of metal-DOM complexation. It is applied to copper and silver using gill complexation constants reported by R. Playle and coworkers. Initial application is made to the fathead minnow data set reported by R. Erickson and a water effects ratio data set by J. Diamond. The use of the BLM for determining total maximum daily loadings (TMDLs) and for regional risk assessments is discussed within a probabilistic framework. At first glance, it appears that a large amount of data are required for a successful application. However, the use of lognormal probability distributions reduces the required data to a manageable amount.
Because concentrations of total or dissolved metal usually are not good predictors of the acute toxicity of metals to aquatic biota (i.e. not all of the metal appears to be bioavailable), it has been tempting for researchers and regulators to attempt to identify a form or combination of forms of a metal that is the bioavailable fraction. But from geochemical, biological, and analytical perspectives, the term ''bioavailable fraction" is context-specific (i.e. not generalizable) and quantitatively elusive. Although the term "bioavailability" conveys a useful, general concept and should be retained in the aquatic-toxicology lexicon, the term "bioavailable fraction" should be avoided.
Biotic ligand models have been developed for various metals (e.g. Cu, Ag, Zn) and different aquatic species. These models incorporate the effect of physico-chemical water characteristics (major cations, pH, dissolved organic carbon) on the bioavailability and toxicity of the metal. In this study, the individual effects of calcium, magnesium, potassium, sodium and pH on zinc toxicity to the green alga Pseudokirchneriella subcapitata (formerly and better known as Selenastrum capricornutum and Raphidocelis subcapitata) were investigated. Stability constants for binding to algal cells (K(BL)) were derived for those cations affecting zinc toxicity, using the mathematical approach proposed by De Schamphelaere and Janssen [Environ. Sci. Technol. 63, (2002) 48-54]. Potassium proved to be the only cation tested that did not alter zinc toxicity to algae significantly. Log (K(BL)) values for Ca, Mg and Na, derived at pH 7.5, were 3.2, 3.9 and 2.8, respectively. Toxicity tests performed at different pH values (5.5-8.0) indicated that competition between H(+) and Zn(2+) reduces zinc toxicity. However, the observed relationship between (H(+)) and the 72h-EbC(50) [expressed as microM (Zn(2+))] is not linear and suggests that pH affects the physiology of the biotic ligand. Although, in general, our findings seem to suggest that zinc toxicity to algae can be modelled as a function of key water characteristics, the results also demonstrate that the part of the conventional BLM-hypothesis-i.e. that the binding characteristics of the biotic ligand are independent of the test medium characteristics-is not valid for algae. The observed pH-dependent change of stability constants should therefore be further investigated and incorporated in future BL-modelling efforts with algae.
Firefly luciferase is often used as a sensitive genetic reporter in various cell types. The pitfall in yeast, however, has been the need to break down the rigid cells in order to measure the enzyme activity. In this study we have removed the peroxisomal targeting codons from the Photinus pyralis luciferase gene (luc) and shown that in the yeast Saccharomyces cerevisiae this modified luciferase gives high levels of light emission that is easy to measure from intact living cells. Furthermore, cells with the modified luciferase grew essentially faster than those with the wild-type luciferase, indicating that peroxisomal targeting of a foreign enzyme puts some constraints to cellular viability. As a model system we used two different reporter constructs. In the first, expression of the luciferase gene is under control of CUP1-promoter, a well known yeast promoter that is inducible by copper ions. In the second, luciferase activity is dependent on activation of the human oestrogen receptor and its interaction with oestrogen-responsive elements incorporated in a yeast promoter. The luciferase activity measurement could be done on a 96-well plate by simple addition of the substrate, D-luciferin, at a moderately acidic pH of 5.0. The ease of use of the non-peroxisomal luciferase makes it an interesting alternative for reporter genes that are conventionally used in yeast, such as lacZ.
The toxicity of contaminated water of different origins and chemicals [Cr(III), Pb(II), Cu(II), Cd(II), pyrene] were tested using four test species: the alga Selenastrum capricornutum (new name Raphidocelis subcapitata), the duckweed Lemna minor, and the crustaceans Thamnocephalus platyurus and Daphnia magna. On the basis of the results obtained, the sensitivity of plant species and problems concerning the interpretation of the phytotoxicity data are discussed. The data indicated that the sensitivities of crustaceans and plant species both to individual contaminants and to mixtures are unpredictable and that there is no reason to consider plant species less sensitive than animal species. Lemna minor is more sensitive than Selenastrum capricornutum. With colored samples, duckweed is preferable for toxicity testing. To raise the predictive utility of the phytotoxicity data, it is recommended that natural water be used in the test procedure.
A small-scale Selenastrum capricornutum (Rhapidocelis subcapitata) growth inhibition assay was applied to the toxicity testing of suspensions of heavy-metal-polluted soils. The OECD 201 standard test procedure was followed, and algal biomass was measured by the fluorescence of extracted chlorophyll. The soils, which contained up to (per kilogram) 1390 mg of Zn, 20 mg of Cd, and 1050 mg of Pb were sampled around lead and zinc smelters in northern France. The water extractability of the metals in suspensions (1 part soil/99 parts water w/v) was not proportional to the pollution level, as extractability was lower for soil samples that were more polluted. Thus, the same amount of metals could be leached out of soils of different levels of pollution, showing that total concentrations of heavy metals in soil (currently used for risk assessment purposes) are poor predictors of the real environmental risk via the soil-water path. Despite high concentrations of water-extracted zinc (0.6-1.4 mg/L of Zn in the test), exceeding by approximately 10-fold the EC(50) value for S. capricornutum (0.1 mg Zn/L), 72-h algal growth in the soil extracts was comparable or better than growth in the standard control OECD mineral medium. The soil suspension stimulated the growth of algae up to eightfold greater than growth using the OECD control medium. Growth stimulation of algae was observed even when soil suspensions contained up to 12.5 mg Zn/L and could not be explained by supplementary nitrogen, phosphorous, and carbonate leached from the soil. However, if the growth of algae in suspensions of clean and polluted soils was compared, a dose-dependent inhibitory effect of metals on algal growth was demonstrated. Thus, as soil contains nutrients/supplements that mask the adverse effect of heavy metals, a clean soil that has properties similar to the polluted soils should be used instead of mineral salt solution as a control for analysis of the ecotoxicity of soils.
A public concern is continuously arising about the presence of natural and anthropogenic compounds which affect human health by modulating normal endocrine functions. These substances, defined as endocrine disrupting compounds (EDC) represent an heterogeneous class of molecules either steroidal or not, sharing the ability of interfering with the endocrine system via nuclear receptor signaling pathways. Therefore there is an urgent need for high throughput screening systems able to detect EDCs and evaluate their biological activity. However, little attention has been dedicated to the development of assays for androgen-like compounds. The present work describes the development and optimization of a new rapid and sensitive bioluminescent yeast-based bioassay for androgen-like compounds in a 96-well microplate format. The bioassay is based on recombinant Saccharomyces cerevisiae cells modified to express human androgen receptor (hAR) and containing the sequence androgen response element (ARE) which drives the expression of Photinus pyralis luciferase, used as reporter gene. A recombinant yeast strain constitutively expressing luciferase was used as external control to correct the light signal accordingly to cell viability and sample matrix aspecific effects. The bioassay responds to testosterone as reference androgen in a concentration-dependent manner from 0.05 to 1000 nM allowing an accurate and precise quantitative evaluation in aqueous environmental samples down to 10(-11)mol/L. Other known androgen-like compounds exhibit similar dose-response behavior, thus permitting the use of the bioassay for an overall detection of androgen-like effect in environmental samples.
In the treatment of synthetic dye wastewater by photosynthetic bacteria under optical irradiation, excessive algal growth and adhesion on the walls of the reactor are serious problems. The adverse effects of excessive algal growth on photosynthetic bacterial activity are significantly greater than those of the decreased optical irradiation of the solution. In this report, we investigated the effects of photocatalysis on the growth of algae (Chroococcus sp.) and photosynthetic bacteria. The different sensitivities of Chroococcus sp. and photosynthetic bacteria to photocatalysis were observed by an ATP assay. Moreover, from microscopy findings, some algae were damaged by TiO2 with UV. We suggested that some algae suffered from membrane damage and consequently cell substances were released, resulting in the increase of dissolved material following treatment using TiO2 with UV.
The combined chemical and ecotoxicological hazard evaluation study was conducted on 60 smelter-influenced soils containing 1 to 13, 50 to 653, and 100 to 1,198 mg/kg of Cd, Pb, and Zn, respectively. For these soils (liquid-to-soil ratio = 10), water extractability of Zn, Cd, and Pb was less than 0.19% (median values). Acetic acid (0.11 M) extracted 23, 9.7, and 0.7% of Cd, Zn, and Pb, respectively. Although heavy metal concentrations in the studied soils were high, the toxic effects of water extracts were observed only in few samples and in few biotests (algae Selenastrum capricornutum and metal detector assay). For most of the aquatic test organisms (e.g., crustaceans, photobacteria), the bioavailable concentrations of metals in soil-water extracts were either subtoxic, or the adverse effects were compensated by soil nutrients, etc. However, analysis of the soils with recombinant Cd sensor Bacillus subtilis (pTOO24) showed that about 65% of these apparently subtoxic samples contained bioavailable Cd when analyzed in the suspension assay (detection limit 1.5 mg Cd/kg soil), indicating the desorption of Cd induced by direct contact of bacteria with soil particles. The median bioavailable fraction of Cd (1%) was 23-fold lower than the fraction extracted by acetic acid. The Pb-Cd sensor Staphylococcus aureus (pT0024) detected bioavailable Pb only in the suspensions of five of the most lead-polluted soils (>417 mg Pb/kg): the median bioavailability of Pb was 0.42%. Consequently, the hazard assessment relying on total metal levels in soils should be revised by critical comparison with data obtained from bioassays. Development and use of biosensors (excellent tools for mechanistic studies and signaling hazard already at subtoxic level) should be encouraged.
The potential eco-toxicity of nanosized titanium dioxide (TiO(2)), silicon dioxide (SiO(2)), and zinc oxide (ZnO) water suspensions was investigated using Gram-positive Bacillus subtilis and Gram-negative Escherichia coli as test organisms. These three photosensitive nanomaterials were harmful to varying degrees, with antibacterial activity increasing with particle concentration. Antibacterial activity generally increased from SiO(2) to TiO(2) to ZnO, and B. subtilis was most susceptible to their effects. Advertised nanoparticle size did not correspond to true particle size. Apparently, aggregation produced similarly sized particles that had similar antibacterial activity at a given concentration. The presence of light was a significant factor under most conditions tested, presumably due to its role in promoting generation of reactive oxygen species (ROS). However, bacterial growth inhibition was also observed under dark conditions, indicating that undetermined mechanisms additional to photocatalytic ROS production were responsible for toxicity. These results highlight the need for caution during the use and disposal of such manufactured nanomaterials to prevent unintended environmental impacts, as well as the importance of further research on the mechanisms and factors that increase toxicity to enhance risk management.
The development of a risk management system for nanoscale or ultrafine particle-types requires a base set of hazard data. Assessing risk is a function of hazard and exposure data. Previously, we have suggested “parallel tracks” as a strategy for conducting nanoparticle research. On the one hand, mechanistic studies on “representative” nanoparticles could be supported by governmental agencies. Alternatively, with regard to commercial nanoparticles, the environmental, health and safety (EHS) framework would include a minimum base set of toxicity studies which should be supported by the companies that are developing nano-based products. The minimum base set could include the following criteria: substantial particle characterization, pulmonary toxicity studies, acute dermal toxicity and sensitization studies, acute oral and ocular toxicity studies, along with screening type genotoxicity, and aquatic toxicity studies.
Increasing use of metallic nanomaterials is likely to result in release of these particles into aqueous environments; however, it is unclear if these materials present a hazard to aquatic organisms. Because some dissolution of metal particles will occur, it is important to distinguish effects of nanoparticulates from dissolved metals. To address this issue, acute toxicity of soluble copper and 80 nm copper nanoparticle suspensions were examined in zebrafish. The results demonstrate that nanocopper is acutely toxic to zebrafish, with a 48 h LC50 concentration of 1.5 mg/L. Rapid aggregation of copper nanoparticles occurred after suspension in water, resulting in 50-60% of added mass leaving the water column. While dissolution of particulate copper occurred, it was insufficient to explain the mortality in nanocopper exposures. Histological and biochemical analysis revealed that the gill was the primary target organ for nanocopper. To further investigate the effects of nanocopper on the gill, zebrafish were exposed to 100 microg/L of nanocopper or to the concentration of soluble copper matching that present due to dissolution of the particles. Under these conditions, nanocopper produced different morphological effects and global gene expression patterns in the gill than soluble copper, clearly demonstrating that the effects of nanocopper on gill are not mediated solely by dissolution.
As the production of nanoparticles of ZnO, TiO2 and CuO is increasing, their (eco)toxicity to bacteria Vibrio fischeri and crustaceans Daphnia magna and Thamnocephalus platyurus was studied with a special emphasis on product formulations (nano or bulk oxides) and solubilization of particles. Our innovative approach based on the combination of traditional ecotoxicology methods and metal-specific recombinant biosensors allowed to clearly differentiate the toxic effects of metal oxides per se and solubilized metal ions. Suspensions of nano and bulk TiO2 were not toxic even at 20 g l(-1). All Zn formulations were very toxic: L(E)C50 (mg l(-1)) for bulk ZnO, nanoZnO and ZnSO4.7H2O: 1.8, 1.9, 1.1 (V. fischeri); 8.8, 3.2, 6.1 (D. magna) and 0.24, 0.18, 0.98 (T. platyurus), respectively. The toxicity was due to solubilized Zn ions as proved with recombinant Zn-sensor bacteria. Differently from Zn compounds, Cu compounds had different toxicities: L(E)C50 (mg l(-1)) for bulk CuO, nano CuO and CuSO4: 3811, 79, 1.6 (V. fischeri), 165, 3.2, 0,17 (D. magna) and 95, 2.1, 0.11 (T. platyurus), respectively. Cu-sensor bacteria showed that toxicity to V. fischeri and T. platyurus was largely explained by soluble Cu ions. However, for Daphnia magna, nano and bulk CuO proved less bioavailable than for bacterial Cu-sensor. This is the first evaluation of ZnO, CuO and TiO2 toxicity to V. fischeri and T. platyurus. For nano ZnO and nano CuO this is also a first study for D. magna.
TiO(2) nanoparticles (< 100 nm diameter) have been reported to cause oxidative stress related effects, including inflammation, cytotoxicity and genomic instability, either alone or in the presence of UVA irradiation in mammalian studies. Despite the fact that the aquatic environment is often the ultimate recipient of all contaminants there is a paucity of data pertaining to the potential detrimental effects of nanoparticles on aquatic organisms. Therefore, these investigations aimed to evaluate the potential cytotoxic and genotoxic effects of TiO(2) nanoparticles on goldfish skin cells (GFSk-S1), either alone or in combination with UVA. Whilst neutral red retention (NRR) assay (a measure of lysosomal membrane integrity) was used to evaluate cell viability, a modified Comet assay using bacterial lesion-specific repair endonucleases (Endo-III, Fpg) was employed to specifically target oxidative DNA damage. Additionally, electron spin resonance (ESR) studies with different spin traps were carried out for qualitative analysis of free radical generation. For cell viability, TiO(2) alone (0.1-1000 microg ml(-1)) had little effect whereas co-exposure with UVA (0.5-2.0 kJm(-2)) caused a significant dose-dependent decrease which was dependent on both the concentration of TiO(2) and the dose of UVA administered. For the Comet assay, doses of 1, 10 and 100 microg ml(-1) in the absence of UVA caused elevated levels of Fpg-sensitive sites, indicating the oxidation of purine DNA bases (i.e. guanine) by TiO(2). UVA irradiation of TiO(2)-treated cells caused further increases in DNA damage. ESR studies revealed that the observed toxic effects of nanoparticulate TiO(2) were most likely due to hydroxyl radical (OH) formation.
In this study, the combined effects of pH, water hardness, and dissolved organic carbon (DOC) concentration and type on the chronic (72-h) effect of copper on growth inhibition of the green alga Pseudokirchneriella subcapitata were investigated. Natural dissolved organic matter (DOM) was collected at three sites in Belgium and The Netherlands using reverse osmosis. A full central composite test design was used for one DOM and a subset of the full design for the two other DOMs. For a total number of 35 toxicity tests performed, 72-h effect concentration resulting in 10% growth inhibition (EbC10s) ranged from 14.2 to 175.9 micrograms Cu/L (factor 12) and 72-h EbC50s from 26.9 to 506.8 micrograms Cu/L (factor 20). Statistical analysis demonstrated that DOC concentration, DOM type, and pH had a significant effect on copper toxicity; hardness did not affect toxicity at the levels tested. In general, an increase in pH resulted in increased toxicity, whereas an increase of the DOC concentration resulted in decreased copper toxicity. When expressed as dissolved copper, significant differences of toxicity reduction capacity were noted across the three DOM types tested (up to factor 2.5). When expressed as Cu2+ activity, effect levels were only significantly affected by pH; linear relationships were observed between pH and the logarithm of the effect concentrations expressed as free copper ion activity, that is, log(EbC50Cu2+) and log(EbC10Cu2+): (1) log(EbC50Cu2+)= - 1.431 pH + 2.050 (r2 = 0.95), and (2) log(EbC10cu2+) = -1.140 pH -0.812 (r2 = 0.91). A copper toxicity model was developed by linking these equations to the WHAM V geochemical speciation model. This model predicted 97% of the EbC50dissolved and EbC10dissolved values within a factor of two of the observed values. Further validation using toxicity test results that were obtained previously with copper-spiked European surface waters demonstrated that for 81% of tested waters, effect concentrations were predicted within a factor of two of the observed. The developed model is considered to be an important step forward in accounting for copper bioavailability in natural systems.
Adsorption of nano-sized TiO 2 particles onto surface of algae exemplified by Pseudokirchneriella subcapitata
- M Y Lin
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- C P Huang
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- Sigma-Aldrich
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Solubility of copper oxides in water and steam
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Algal growth inhibition test
- Organisation for Economic Cooperation and Development
Adsorption of nano-sized TiO2 particles onto surface of algae exemplified by Pseudokirchneriella subcapitata
- Lin
Nanoparticles in the aquatic environment — aggregation behaviour of TiO2 nanoparticles studied in a simplified aqueous test matrix (SAM)
- Ottofuelling