Assessment of Crystal Morphology on Uptake, Particle Dissolution, and Toxicity of Nanoscale Titanium Dioxide on Artemia salina

Meta-analysis of Bioaccumulation Data for Nondissolvable Engineered Nanomaterials in Freshwater Aquatic Organisms

Understanding the bioaccumulation of engineered nanomaterials (ENMs) is essential for making regulatory decisions on potential environmental risks. Research in the field of ENM bioaccumulation has increased in recent years, but the compilation and statistical analysis of the available experimental data have not been updated. We therefore performed a meta-analysis of the existing literature on the bioaccumulation of eight types of nondissolvable ENMs (titanium dioxide [TiO₂ ], aluminum oxide [Al₂ O₃ ], gold [Au], fullerene [C₆₀ ], carbon nanotubes, iron oxide [FeO_x ], graphene, and polystyrene) in nonmammalian freshwater aquatic organisms across three trophic levels including phytoplankton, zooplankton, and fish. Three typical endpoints were used to assess the bioaccumulation potential: the bioconcentration factor (BCF), the bioaccumulation factor (BAF), and the biomagnification factor (BMF). Our results suggest that zooplankton has greater mean logarithmic BCF and BAF values than phytoplankton (3.31 vs. 1.42) and fish (2.04). The ENMs are biomagnified in zooplankton, with a mean BMF of 17.4, whereas trophic transfer from primary consumers (zooplankton) to secondary consumers (fish) was not observed (mean BMF of 0.13). No clear dependency was identified between the physicochemical characteristics of ENMs (e.g., primary particle size, zeta potential, or shape) and bioaccumulation, except for coated versus uncoated particles accumulated in phytoplankton. Carbonaceous ENMs were found to be more bioaccumulated than the other ENMs we considered, except for TiO₂ . A meta-analysis of bioaccumulation data can (1) deepen the understanding of bioconcentration, bioaccumulation, and biomagnification of ENMs, (2) be used to support grouping strategies as a basis for a safer-by-design approach for ENMs, (3) be integrated into comprehensive hazard and risk assessments, (4) promote the standardization of testing guidelines, and (5) enhance future kinetic bioaccumulation modeling. Environ Toxicol Chem 2022;41:1202-1214. © 2022 The Authors. Environmental Toxicology and Chemistry published by Wiley Periodicals LLC on behalf of SETAC.

Preparation of SrTiO3 nanocubes by CO2 laser vaporization (LAVA) and hydrothermal maturation

SrTiO3 is of particular interest for numerous applications such as photocatalytic water splitting, as an electrode material for thermoelectrics or as piezoceramics for sensors. Here we report on an advanced CO2 laser vaporization (LAVA) method for the production of faceted, single-phase SrTiO3 nanoparticles with an average particle size of 35 nm. Starting from a coarse SrTiO3 raw powder, spherical SrTiO3 nanoparticles were obtained by a laser-induced gas-phase condensation process. The composition of the nanoparticles corresponds to that of the starting powder, as XRD and FT-IR measurements show. Further hydrothermal treatment at 275 °C for 4 hours leads to the formation of faceted nanocubes with increasing crystallite size, as demonstrated by TEM, HR-TEM and XRD measurements. During a final washing step in 0.1 M HCl, SrCO3 impurities were dissolved and thus single-phase SrTiO3 nanocubes were successfully obtained, as shown by FT-IR, XRD and TEM analyses. The presented process facilitates the production of single-phase, highly crystalline SrTiO3 nanopowders in sufficient quantities for subsequent use in a variety of applications, in particular for hydrogen production by photocatalytic water splitting.

Eco-Interactions of Engineered Nanomaterials in the Marine Environment: Towards an Eco-Design Framework

Marine nano-ecotoxicology has emerged with the purpose to assess the environmental risks associated with engineered nanomaterials (ENMs) among contaminants of emerging concerns entering the marine environment. ENMs’ massive production and integration in everyday life applications, associated with their peculiar physical chemical features, including high biological reactivity, have imposed a pressing need to shed light on risk for humans and the environment. Environmental safety assessment, known as ecosafety, has thus become mandatory with the perspective to develop a more holistic exposure scenario and understand biological effects. Here, we review the current knowledge on behavior and impact of ENMs which end up in the marine environment. A focus on titanium dioxide (n-TiO₂) and silver nanoparticles (AgNPs), among metal-based ENMs massively used in commercial products, and polymeric NPs as polystyrene (PS), largely adopted as proxy for nanoplastics, is made. ENMs eco-interactions with chemical molecules including (bio)natural ones and anthropogenic pollutants, forming eco- and bio-coronas and link with their uptake and toxicity in marine organisms are discussed. An ecologically based design strategy (eco-design) is proposed to support the development of new ENMs, including those for environmental applications (e.g., nanoremediation), by balancing their effectiveness with no associated risk for marine organisms and humans.

An insight into the dependency on sample preparation for (eco) toxicity assessment of TiO2 nanoparticles

Assessing the environmental hazard of nanoparticles can be a challenging task using various testing strategies. However, to our knowledge, no information is available about the impact of the sample preparation on the toxicity and toxicity mechanism of nanoparticles. For this aim, three sample preparation methods and their available toxicity procedures were conducted to examine the (eco) toxicity of TiO₂ nanoparticles using bacteria model system. To detail understanding of the effect of sample preparation, the key events on the inhibition were examined by physicochemical and antioxidant responses. The findings showed that the physicochemical and toxicological behavior of the tested TiO₂ NPs varied according to the sample preparation method.

Differential in vivo hemocyte responses to nano titanium dioxide in mussels: Effects of particle size

Titanium dioxide nanoparticles (TiO₂ NPs) are widely used in various products and inevitably released with different sizes and forms into aquatic environment. The purpose of this study was to assess the differential immune toxicity of TiO₂ NPs with size difference on mussel hemocytes using flow cytometry (FCM) assays. Hemocyte parameters, including total hemocyte count (THC), hemocyte mortality (HM), phagocytosis activity (PA), lysosomal content (LC), esterase activity (EA), mitochondrial number (MN), mitochondrial membrane potential (MMP) and reactive oxygen species content (ROS) were evaluated in the mussels Mytilus coruscus exposed to two types of TiO₂ NPs (25nm & 100nm: 0.1, 1, 10 mg/L, respectively). In general, size- and concentration-dependent toxicity was pronounced with 25nm-NP and highest concentration (10mg/L) being the most toxic. Alhough a slight recovery from the TiO₂ exposure was observed, significant carry-over effects were still detected. These results highlight the importance of differential size effects of metal oxide NPs on toxicity mechanisms in aquatic animals.