The biological toxicities of two crystalline phases and differential sizes of TiO2 nanoparticles during zebrafish embryogenesis development

Research advance of occupational exposure risks and toxic effects of semiconductor nanomaterials

In recent years, semiconductor nanomaterials, as one of the most promising and applied classes of engineered nanomaterials, have been widely used in industries such as photovoltaics, electronic devices, and biomedicine. However, occupational exposure is unavoidable during the production, use, and disposal stages of products containing these materials, thus posing potential health risks to workers. The intricacies of the work environment present challenges in obtaining comprehensive data on such exposure. Consequently, there remains a significant gap in understanding the exposure risks and toxic effects associated with semiconductor nanomaterials. This paper provides an overview of the current classification and applications of typical semiconductor nanomaterials. It also delves into the existing state of occupational exposure, methodologies for exposure assessment, and prevailing occupational exposure limits. Furthermore, relevant epidemiological studies are examined. Subsequently, the review scrutinizes the toxicity of semiconductor nanomaterials concerning target organ toxicity, toxicity mechanisms, and influencing factors. The aim of this review is to lay the groundwork for enhancing the assessment of occupational exposure to semiconductor nanomaterials, optimizing occupational exposure limits, and promoting environmentally sustainable development practices in this domain.

Phytotoxicity of VO2 nanoparticles with different sizes to pea seedlings

Vanadium dioxide nanoparticles (VO2 NPs) have been massively produced due to their excellent metal-insulator transition characteristics for various applications. Pilot studies indicated the toxicity of VO2 NPs to bacteria and mammalian cells, but the environmental hazards of VO2 NPs to plants have been unrevealed to date. In this study, we reported the inhibitive effects of VO2 NPs to the growth and photosynthesis of pea seedlings. Laboratory synthesized monoclinic VO2 NPs (N-VO2), commercial nanosized VO2 NPs (S-VO2), and commercial microsized VO2 particles (M-VO2) were carefully characterized for environmental toxicity evaluations. VO2 particles were supplemented to culture medium for seed germination and seedling growth. All three VO2 samples did not affect the germination rates of pee seeds, while serious growth inhibition of pea seedlings was observed at 10 mg/L for S-VO2 and N-VO2, and 100 mg/L for M-VO2. VO2 particles had no impact on the chlorophyll contents, but the photosynthesis of leaf was significantly decreased following the consequence of N-VO2 > S-VO2 > M-VO2. The inhibition of photosynthesis was attributed to the damage of acceptor side of photosystem II by VO2 particles at high concentrations. Abundant bioaccumulations of vanadium in roots aroused oxidative damage and changed the root structure. Our results collectively indicated that the phytotoxicity of VO2 NPs was related to the concentration, size and crystalline degree.

The nano-bio interactions of rare-earth doped BaF2 nanophosphors shape the developmental processes of zebrafish

Nanoparticles with biomedical applications should be evaluated for their biocompatibility. Rare-earth doped nanoparticles with unique spectral properties are superior in vivo optical probes in comparison with quantum dots and organic dyes, however, studies describing their nano-bio interactions are still limited. Here, we have evaluated the nano-bio interactions of green-synthesized, phase-pure BaF₂ nanoparticles doped with rare-earth (RE³⁺ = Ce³⁺/Tb³⁺) ions using larval zebrafish. We found that zebrafish can tolerate a wide concentration range of these nanoparticles, as the maximal lethality was observed at very high concentrations (more than 200 mg L^-1) upon five days of continuous exposure. At a concentration of 10 mg L^-1, at which Zn²⁺, Ti⁴⁺ and Ag⁺ nanoparticles are reported to be lethal to developing zebrafish, continuous exposure to our nanoparticles for four days produced no developmental anomalies, craniofacial defects, cardiac toxicity or behavioural abnormalities in the developing zebrafish larvae. We have also found that the doping of rare-earth ions has no major effect on these biomarkers. Interestingly, the function of acetylcholinesterase (AChE) and the cellular metabolic activity of whole zebrafish larvae remained unchanged, even during continuous exposure to these nanoparticles at 150 mg L^-1 for four days; however, severe developmental toxicities were evident at this high concentration. Based on these results, we can conclude that the biocompatibility of rare-earth doped nanoparticles is concentration dependent. Not all biomarkers are sensitive to these nanoparticles. The high concentration-dependent toxicity occurs through a mechanism distinct from changes in the metabolic or AChE activity. The significance of these findings lies in using these nanoparticles for bioimaging applications and biomarker studies, especially for prolonged exposure times.

In silico prediction of MicroRNA role in regulation of Zebrafish (Danio rerio) responses to nanoparticle exposure

The release of nanoparticles to the environment can affect health of the exposed organisms. MicroRNAs have been suggested as potential toxicology biomarkers, however the information about use of microRNA in aquatic organisms exposed to nanoparticles (NP) is limited. In silico analysis from publicly available gene expression data was performed. Data selection for the analysis was based on reported biological and pathological outcomes of NP induced toxicity in zebrafish. After identifying relevant genes, we constructed six miRNA-mRNA regulatory networks involved in nanoparticle induced toxicological responses in zebrafish. Based on our prediction and selection criteria we selected six miRNAs that overlapped in constructed networks with remarkable prediction score, and were validated by previous mammalian and zebrafish microRNA profiling studies: dre-miR-124, -144, -148, -155, -19a, -223. The results of this in silico analysis indicate that several highly conserved miRNAs likely have a regulatory role of organismal responses to nanoparticles, and can possibly be used as biomarkers of nanotoxicity in studies using zebrafish as model organism One health approaches.

Toxicological effects of transition metal-doped titanium dioxide nanoparticles on goldfish (Carassius auratus) and common carp (Cyprinus carpio)

The aim of present study was to assess the toxicological effects of transition metal-doped titanium dioxide nanoparticles (TiO₂ NPs) on histopathological changes, behavioral patterns, and antioxidant responses of goldfish (Carassius auratus) and common carp (Cyprinus carpio). The synthesized nanoparticles were confirmed by Transmission Electron Microscopy, Field Emission Scanning Electron Microscopy, X-ray diffraction, UV-visible, and Vibration Sample Magnetometer. Fish in four experimental groups exposed to sub-lethal concentrations of pure TiO₂ NPs (10 mg L^-1), chromium (Cr), iron (Fe), and nickel (Ni) doped TiO₂ NPs for seven days. Statistical analysis of oxidative stress responses in gills showed significant differences in superoxide dismutase, total antioxidant capacity, and malondialdehyde parameters between two species and in all parameters than glutathione peroxidase between experimental groups and control group. In intestine, no significant difference was observed among groups, but oxidative responses were markedly different in all parameters among fish species. The histopathological analysis showed hyperplasia, fusion, and aneurism in the gills as well as degeneration, integration of villi, necrosis and erosion of the intestine. Our findings indicated that compare to pure TiO₂ NPs, exposure to transition metals-doped TiO₂ NPs induced oxidative stress and histopathological changes in both fish species.

Trophic transfer of nano-TiO2 in a paddy microcosm: A comparison of single-dose versus sequential multi-dose exposures

In the present study, replicated paddy microcosm systems were used to investigate the environmental fate and trophic transfer of titanium nanoparticles (NPs) over a period of 14 days. Most TiO2 NPs immediately settled down in the sediment, and high accumulations of nano TiO2 in the sandy loam sediment and biofilm were observed. The test organisms (quillworts, water dropworts, duckweeds, biofilms, river snails, and Chinese muddy loaches) and environmental media (freshwater, sandy loam sediment) were exposed to sequential low doses (2 mg/L at 1 h, 4 days, and 9 days) or a single high-dose (6 mg/L) of TiO2 NPs. The bioconcentration factors (BCFs) of nano-TiO2 in biofilms, quillworts, duckweeds, and Chinese muddy loaches were higher in the sequential multi-dose group than in the single-dose group. Chinese muddy loaches showed higher bioaccumulation factors (BAFs) over their prey than river snails. The difference in the carbon isotope ratios between Chinese muddy loaches and river snails was less than 2‰, and an approximately 4‰ difference in the stable nitrogen isotope ratio was observed in the two aquatic predators from their major prey (e.g., biofilms or particulate organic matter). The trophic levels between biofilms and river snails and between biofilms and Chinese muddy loaches were 2.8 and 2.4 levels, respectively. These results indicate that these two predators consumed biofilm and other alternative preys at a higher level than biofilm. Although the trophic transfer rates of TiO2 are generally low, relatively higher biomagnification factors (BMFs) were found in Chinese muddy loaches (0.04-0.05) than in river snails (0.01-0.02). These results suggest that TiO2 NPs show greater movement in the sediment than in the water and that TiO2 NPs can be retained through aquatic food chains more after a sequential low-dose exposure than after a single high-dose exposure.

Induction of size-dependent breakdown of blood-milk barrier in lactating mice by TiO2 nanoparticles

This study aims to investigate the potential nanotoxic effects of TiO₂ nanoparticles (TNPs) to dams and pups during lactation period. TiO₂ nanoparticles are accumulated in mammary glands of lactating mice after i.v. administration. This accumulation of TiO₂ NP likely causes a ROS-induced disruption of tight junction of the blood-milk barrier as indicated by the loss of tight junction proteins and the shedding of alveolar epithelial cells. Compared to larger TNPs (50 nm), smaller ones (8 nm) exhibit a higher accumulation in mammary glands and are more potent in causing perturbations to blood-milk barrier. An alarming finding is that the smaller TNPs (8 nm) are transferred from dams to pups through breastfeeding, likely through the disrupted blood-milk barrier. However, during the lactation period, the nutrient quality of milk from dams and the early developmental landmarks of the pups are not affected by above perturbations.

Detection and characterization of SiO2 and TiO2 nanostructures in dietary supplements

Nanomaterials are beginning to enter our daily lives through various consumer products as the result of technology commercialization. The development of methodologies to detect the presence of nanomaterials in consumer products is an essential element in understanding our exposure. In this study, we have developed methods for the separation and characterization of silicon dioxide (SiO2) and titanium dioxide (TiO2) nanostructures in dietary supplements marketed in products specifically targeted for women. A total of 12 commercial products claiming the inclusion of SiO2 and TiO2, but not making any claims regarding the particle size, were randomly selected for purchase through various retailers. To isolate nanostructures from these products, a simple methodology that combines acid digestion and centrifugation was utilized. Once isolated, the chemical composition, size, morphology, and crystal structure were characterized using mass spectroscopy, light scattering, electron microscopy, and X-ray diffraction techniques. SiO2 and TiO2 nanostructures were detected in 11 of 12 products using these methods. Many of the isolated nanoscale materials showed a high degree of aggregation; however, identified individual structures had at least one dimension below 100 nm. These robust methods can be used for routine monitoring of commercial products for nanoscale oxides of silica and titanium.

Cytotoxicity, DNA damage, and apoptosis induced by titanium dioxide nanoparticles in human non-small cell lung cancer A549 cells

Concerns about the risk of titanium dioxide nanoparticles (TiO2 NPs) to human health and environment are gradually increasing due to their wide range of applications. In this study, cytotoxicity, DNA damage, and apoptosis induced by TiO2 NPs (5 nm) in A549 cells were investigated. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assays revealed the time- and concentration-dependent cytotoxic effects of TiO2 NPs in a concentration range of 50 to 200 μg/mL. A statistically significant (p < 0.05) induction in DNA damage was observed by the comet assay in cells exposed to 50 to 200 μg/mL TiO2 NPs for 48 h. A significant (p < 0.05) induction in micronucleus formation determined by 4,6-diamino-2-phenylindole (DAPI) staining was also observed at the above concentrations. Typical apoptotic morphological feature and apoptotic bodies in A549 cells induced by TiO2 NPs at the above concentrations were observed by scanning electron micrographs. Flow cytometric analysis demonstrated that the cells treated with TiO2 NPs at concentrations of 100 and 200 μg/mL showed a significant G2/M phase arrest and a significant increased proportion of apoptotic cells. TiO2 NPs also disrupted the mitochondrial membrane potential evaluated by rhodamine 123 staining. Further analysis by quantitative real-time PCR (qRT-PCR) indicated that the expression of caspase-3 and caspase-9 messenger RNA (mRNA) was increased significantly at the concentrations of 100 and 200 μg/mL TiO2 NPs for 48 h. Taken together, these findings suggest that TiO2 NPs can inhibit A549 cell proliferation, cause DNA damage, and induce apoptosis via a mechanism primarily involving the activation of the intrinsic mitochondrial pathway. The assay data provide strong evidence that TiO2 NPs can induce cytotoxicity, significant DNA damage, and apoptosis of A549 cells, suggesting that exposure to TiO2 NPs could cause cell injury and be hazardous to health.