More attention has been recently paid to the ecotoxicity of titanium dioxide nanoparticles (nano-TiO2) owing to its common use in many fields. Although previous studies have shown that nano-TiO2 is ...neurotoxic, the mechanism is still largely unknown. In the present study, zebrafish embryos were exposed to 0.01, 0.1, and 1.0 mg/L nano-TiO2 and 1.0 mg/L micro-TiO2 for up to 6 days post-fertilization (dpf). Exposure to 1.0 mg/L nano-TiO2 significantly decreased the body length and weight of zebrafish larvae; however, the hatching and mortality rate of zebrafish embryos did not change. Behavioral tests showed that nano-TiO2 exposure significantly reduced the swimming speed and clockwise rotation times of the larvae. The results revealed that nano-TiO2 treatment adversely affected motor neuron axon length in Tg (hb9-GFP) zebrafish and decreased central nervous system (CNS) neurogenesis in Tg (HuC-GFP) zebrafish. Additionally, real-time polymerase chain reaction analysis demonstrated that genes associated with neurogenesis (nrd and elavl3) and axonal growth (α1-tubulin, mbp, and gap43) were significantly affected by nano-TiO2 exposure. In conclusion, our study demonstrated that early-life stage exposure of zebrafish to nano-TiO2 causes adverse neural outcomes through the inhibition of neurodevelopment and motor neuron axonal growth.
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•Titanium dioxide nanoparticles exposure induced neurotoxicity.•Titanium dioxide nanoparticles exposure markedly decreased locomotor behavior.•Titanium dioxide nanoparticles exposure decreased central nervous system (CNS) neurogenesis in Tg (HuC-GFP) zebrafish.•Titanium dioxide nanoparticles exposure adversely affected motor neuron axon length in Tg (hb9-GFP) zebrafish.•Titanium dioxide nanoparticles exposure downregulate the expression levels of neurodevelopment genes.
Due to its relatively simple preparation and readily available precursors, determination of triacetone triperoxide (TATP) by portable devices has become important. In this work, two different ...titanium dioxide nanoparticles (TiO2NPs)–based colorimetric sensors based on complex formation on the solid surface were developed for determination of H2O2 and TATP. The first sensor, (3-aminopropyl)triethoxysilane (APTES) modified-TiO2NPs–based paper sensor (APTES@TiO2NPs), exploits peroxo-titanate binary complex formation between APTES@TiO2NPs and H2O2 on chromatographic paper. The second sensor, 4-(2-pyridylazo)-resorcinol-modified-TiO2NPs–based solid sensor (PAR@TiO2NPs), relies on the formation of a ternary complex between Ti(IV), PAR and H2O2. The developed sensors were also applied to TATP determination after acidic hydrolysis of samples to H2O2. The limits of detection (LODs) of APTES@TiO2NPs–based paper sensor were 3.14 × 10−4 and 5.13 × 10−4 mol L−1 for H2O2 and TATP, respectively, whereas the LODs of PAR@TiO2NPs solid sensor were 6.06 × 10−7 and 3.54 × 10−7 mol L−1 for H2O2 and TATP, respectively. Possible interferences of common soil ions, passenger belongings used as camouflage materials during public transport (e.g., detergent, sweetener, acetylsalicylic acid and paracetamol-caffeine based analgesic drugs) and of other explosives were examined. The developed methods were statistically validated using t- and F- tests against the titanyl sulfate (TiOSO4) colorimetric literature method.
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•Two novel TiO2 nanoparticles–based reflectometric sensors were devised for TATP detection.•TATP was detected after hydrolysis to H2O2 and binary or ternary complexation with TiO2.•NanoTiO2-H2O2-PAR solid sensor enabled detection as sensitive as 0.35 μM.•Both paper and solid sensors for TATP were validated and interference-resistant.•The recommended sensors allow onsite analysis with solvent savings and waste control.
Titanium dioxide nanoparticles (TiO2-NP) present in wastewater effluent are discharged into freshwater and saltwater (i.e., marine) systems. TiO2-NP can be solar-driven photoactivated by ultraviolet ...(UV)-light producing reactive oxygen species including hydroxyl radicals (·OH). ·OH are non-selective and react with a broad range of species in water. In other studies, photoactivation of TiO2-NP has been correlated with oxidative stress and ecotoxicological impacts on plant and animal biota. This study examined the photoactivation of TiO2-NP in freshwater and saltwater systems, and contrasted the oxidation potential in both systems using methylene blue (MB) as a reaction probe. Maximum MB loss (51.9%, n = 4; 95% confidence interval 49.4–54.5) was measured in salt-free, deionized water where ·OH scavenging was negligible; minimum MB loss (1%) was measured in saltwater due to significant ·OH scavenging, indicating the inverse correlation between MB loss and radical scavenging. A kinetic analysis of scavenging by seawater constituents indicated Cl− had the greatest impact due to high concentration and high reaction rate constant. Significant loss of MB occurred in the presence of Br− relative to other less aggressive scavengers present in seawater (i.e., HCO3−, HSO4−). This result is consistent with the formation of Bromate, a strong oxidant that subsequently reacts with MB. In freshwater samples collected from different water bodies in Oklahoma (n = 12), the average MB loss was 13.4%. Greater MB loss in freshwater systems relative to marine systems was due to lower ·OH scavenging by various water quality parameters. Overall, TiO2-NP photoactivation in freshwater systems has the potential to cause greater oxidative stress and ecotoxicological impacts than in marine systems where ·OH scavenging is a dominant reaction.
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•TiO2-NP photoactivation yields strong, non-selective hydroxyl radicals (·OH).•Probe oxidation in seawater < in fresh water body samples (n = 12).•·OH scavenging in seawater is attributed primarily to Cl−.•Seawater: OH scavenging rate/probe oxidation rate ∼11,400.•Oxidative stress effects in freshwater systems > marine systems.
Tri-phase TiO2 nanoparticles are synthesized by facile hydrothermal method and calcinated within a temperature range of 450 °C–1050 °C. These nanoparticles are utilized as photoanode material in ...dye-sensitized solar cell (DSSC) applications. The device fabricated by utilizing TiO2 NPs calcinated at 600 °C reveals a maximum power conversion efficiency (η) of 3.79 %, with a current density (Jsc) of 7.83 mA cm−2 under one sun illumination among all tested devices. This exceptional achievement is related to the synergistic effect of 49 wt % anatase, 39 wt % rutile and 12 wt % brookite content in triphasic TiO2 NPs. The anatase emerges as the most active phase providing a sufficient surface area for dye adsorption, and in parallel rutile phase enhances the scattering of light that potentially boosts mobility and injection of photogenerated electrons (e-s) from the LUMO level (ELUMO = −3.8 eV) of N719 dye to the conduction band (ECB = −4.28 eV). Simultaneously, the presence of the brookite phase reduces the charge-carriers ((e−), (h+)) recombination rate at the TiO2 photoelectrode/electrolyte interfaces because brookite has an inherent resistance to back electron transfer. The effective light-harvesting capabilities of triphasic TiO2 NPs position them as promising contenders for dye-sensitized solar cells (DSSCs).
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•TiO2 NPs are synthesized by hydrothermal method and calcinated at 450 °C, 600 °C, 750 °C, 900 °C and 1050 °C.•TiO2 NPs consist of tri-phase (A, R, B) up to 600 °C, dual (A, R) at 750 °C and single (R) phases at 900 °C, 1050 °C.•The optical absorption edge of TiO2 NPs steadily increases in the visible region with increasing calcination.•The fabricated DSSC with TiO2 NPs at 600 °C achieves the highest PCE of η ∼3.79 %, among all tested devices.•The enhancement in “η” is due to the synergistic response of anatase, rutile, and brookite phases in TiO2.
•TiO2 NPs covered the biofilm surface and entered the intracellular region.•Nitrogen metabolism was interfered under long-term TiO2 NPs stress in CWs.•Glycolysis metabolism was interfered under ...long-term TiO2 NPs stress in CWs.•ATP and NADH production declined under long-term TiO2 NPs stress in CWs.•Prolonged TiO2 NPs stress weakened the nitrogen transformation efficiency in CWs.
Extensive use of titanium dioxide nanoparticles (TiO2 NPs) in various products has increased the release of these particles into wastewater, posing potential environmental risks. As an ecological wastewater treatment facility, constructed wetland (CW) is an important sink of NPs. However, little is known about the effects of NPs on microbial nitrogen transformation and related genes in CWs. In this study, short-term (5 days) and long-term (60 days) exposure experiments were conducted to investigate the effect of TiO2 NPs (0, 1, and 50 mg/L) on microbial nitrogen removal in CWs. The results showed that nitrogen removal efficiency was decreased by 35%–51% after long-term exposure to TiO2 NPs. Metagenomic analysis further confirmed that TiO2 NPs declined the relative abundance of functional genes and those enzyme encoding genes involved in the nitrogen metabolism pathway and glycolysis metabolism process. Furthermore, our data proved that the indigent glycolysis metabolism process resulted in the shortage of electron (NADH) and energy sources (ATP), causing inefficient nitrogen removal. Overall, these results revealed that the accumulation of TiO2 NPs altered the genetic expression of biofilm in CWs, which had significant impacts on biological nitrogen transformation.
Transport behaviors of titanium dioxide nanoparticles (nTiO2) were examined in the individual- and co-presence Escherichia (E.) coli and phosphate in heterogeneous sand (uncoated and iron ...oxyhydroxide-coated sand) columns. The results showed that for the individual presence of phosphate, the degree of nTiO2 deposition was less in uncoated than in iron oxide-coated sands. In contrast, an opposite trend that greater deposition of nTiO2 in uncoated than in coated sands occurred in the individual presence of E. coli. These observations are due to the phosphate adsorption changing the charge of NPs and iron oxyhydroxide-coated sand, or the preferential adhesion of bacterial to coated sand. In the copresence of E. coli and phosphate, interestingly, the phosphate level plays an important role in influencing nTiO2 transport. At a high phosphate concentration (>1.0 mM), the deposition of nTiO2 with the individual presence of E. coli was stronger than nTiO2 in the copresence of both E. coli and phosphate, regardless of sand type. The potential mechanism was that phosphate adsorption led to the formation of more negatively charged NPs-bacteria complexes that have higher mobility in sand columns. At a low phosphate level (≤0.1 mM), a similar observation occurred in uncoated sand. Nevertheless, the deposition of nTiO2 with copresence of E. coli and phosphate was greater than nTiO2 with E. coli in oxyhydroxide-coated sand. It was attributed to the formation of large NPs-bacteria-phosphate clusters (less mobile) and the preferential adhesion of E. coli cells to iron oxyhydroxide coating simultaneously. Taken together, our findings provide crucial knowledge for better understanding the fate, transport, and potential risks of engineered nanoparticles in complicated environmental settings where bacteria and phosphate are ubiquitous.
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•Transport of nTiO2 w. P was different in heterogeneous sand from that w. E. coli.•Deposition of nTiO2 with E. coli was higher in uncoated than in coated sand.•Adhesion affinity of E. coli or P on coated sand accounted for different transport.•P level plays important role in influencing transport of nTiO2 w. E. coli + P.
RNA N6-methyladenosine (m6A) modification regulates the cell stress response and homeostasis, but whether titanium dioxide nanoparticle (nTiO2)-induced acute pulmonary injury is associated with the ...m6A epitranscriptome and the underlying mechanisms remain unclear. Here, the potential association between m6A modification and the bioeffects of several engineered nanoparticles (nTiO2, nAg, nZnO, nFe2O3, and nCuO) were verified thorough in vitro experiments. nFe2O3, nZnO, and nTiO2 exposure significantly increased the global m6A level in A549 cells. Our study further revealed that nTiO2 can induce m6A-mediated acute pulmonary injury. Mechanistically, nTiO2 exposure promoted methyltransferase-like 3 (METTL3)-mediated m6A signal activation and thus mediated the inflammatory response and IL-8 release through the degeneration of anti-Mullerian hormone (AMH) and Mucin5B (MUC5B) mRNAs in a YTH m6A RNA-binding protein 2 (YTHDF2)-dependent manner. Moreover, nTiO2 exposure stabilized METTL3 protein by the lipid reactive oxygen species (ROS)-activated ERK1/2 pathway. The scavenging of ROS with ferrostatin-1 (Fer-1) alleviates the ERK1/2 activation, m6A upregulation, and the inflammatory response caused by nTiO2 both in vitro and in vivo. In conclusion, our study demonstrates that m6A is a potential intervention target for alleviating the adverse effects of nTiO2-induced acute pulmonary injury in vitro and in vivo, which has far-reaching implications for protecting human health and improving the sustainability of nanotechnology.
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•nTiO2 exposure changed global m6A modification level in A549 and Beas-2B cells.•nTiO2 induces acute pulmonary injury through the METTL3-mediated m6A upregulation.•nTiO2 exposure stabilize METTL3 protein by lipid ROS activated ERK1/2 pathway.•ROS/ERK/METTL3/m6A pathway determines acute pulmonary injury caused by nTiO2.
A field study was designed to explore the impacts of foliar-applied chemically and green synthesized titanium dioxide nanoparticles (TiO2 NPs) on cadmium (Cd) uptake in wheat plants. The wheat was ...grown in field which was contaminated with Cd and plants were subjected to foliar episodes of TiO2 NPs during plant growth period. Leaf extracts of two plant species (Trianthema portulacastrum, Chenopodium quinoa) were used for green synthesis while sol-gel method was used for chemical preparation of TiO2 NPs. Results showed that TiO2 NPs significantly enhanced the plant height, length of spikes photosynthesis, and straw and grain yield compared to control. TiO2 NPs minimized the oxidative burst in leaves and improved the enzyme activities than control. Cadmium concentrations of straw, roots and grains decreased after TiO2 NPs treatments than control. The grain Cd contents were below recommended threshold (0.2 mg Cd /kg grain DW) for cereals upon NPs exposure. The health risk index by the dietary use of grains for adults was below threshold upon NPs exposure. Overall, foliar use of TiO2 NPs prepared from plant extracts was appropriate in minimizing Cd contents in wheat grains, thereby reducing risk of Cd to human health via food chain.
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•Foliar exposure of TiO2 NPs resulted in higher yield of wheat grown in Cd-contaminated field•Foliar use of TiO2 NPs resulted in higher chlorophyll contents under Cd stress•TiO2 NPs caused reduction in oxidative stress in plants under Cd stress•TiO2 NPs significantly decreased Cd in wheat straw, roots, and grains•TiO2 NPs decreased the Cd human health risk by use of grains from Cd-contaminated field
Natural organic matter (NOM) and iron oxides have been proved to be crucial factors controlling the behaviors of nanoparticles in heterogenous environment. Here, we conducted experimental and ...modeling study on the transport of titanium dioxide nanoparticles (TiO2 NPs) in iron oxide-coated quartz in the presence of NOM under acidic conditions. Results showed the antagonistic effects of iron oxides and NOM on TiO2 NPs mobility. The inhibition of iron oxides coated on quartz was crystal form-dependent other than quantity-dependent. Amorphous ferric oxyhydroxide with higher specific surface area brought more positive charge and favorable deposition sites onto quartz, and induced more retention of nanoparticles than two crystalline iron oxides, goethite and hematite. Dissolved organic matter (DOM) facilitated TiO2 NPs transport in iron oxide-coated quartz. In comparation with the limited enhancing effects of DOM, the NOM coatings on media surface partially or largely offset the inhibition of goethite on nanoparticles mobility through direct occupation of attachment sites and sites screening due to the steric repulsion of the macromolecules. Owing to the higher steric hindrance, humic acid, both in dissolved and media surface-bound states, exerted stronger facilitating effects on TiO2 NPs mobility relative to fulvic acid.
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•The inhibition of iron oxides on TiO2 NPs mobility depended on the crystal form.•DOM had limited enhancing effects on TiO2 NPs mobility in iron oxide-coated quartz.•Media-bound NOM alleviated/offset the inhibition of iron oxides on TiO2 NPs mobility.•HA with stronger steric hindrance exerted higher enhancing effects than FA.
Drought stress is reducing the production of crops globally. This research was designed to evaluate the role of titanium dioxide (TiO2 NPs) nanoparticles and calcium phosphate on wheat facing drought ...stress. TiO2 NPs were prepared by green synthesis and their characterization (by UV–visible spectroscopy, scanning electron microscopy (SEM), and energy-dispersive X-ray (EDX)) was also done. The results showed that TiO2 NPs worked efficiently and improved plant growth under drought. However, the best results were obtained from combined applications of 40 ppm TiO2 NPs and 40 ppm calcium phosphate on plants. They increased root length (33%), shoot length (53%), fresh weight (48%), and dry weight (44%) of wheat as compared to control. The physiological parameters including chlorophyll content, relative water content, membrane stability index, and osmolyte content (proline and sugar) were also improved. The increase in superoxide dismutase, peroxidase and, catalase activity by the combined application of TiO2 NPs and calcium phosphate was 83% and 78%, 74% and 52%, 81%, and 67% in Pakistan-13 and Zincol-16 respectively, as compared to untreated drought exposed plants. They also enhanced the nutrients uptake (including potassium, phosphorus, and nitrogen) that ultimately improved plant biomass. They also maintained the level of growth hormones in plants. These hormones regulate cellular processes and are responsible for germination, development, and plant reaction in drought stress. The increase in the yield was also significant, hence it is recommended that the 40 ppm concentration of TiO2 NPs along with calcium phosphate improves the productivity of wheat under drought stress.
•Drought stress affects growth, physio-biochemical attributes, activity of enzymatic antioxidants and productivity of wheat plants.•Application of Titanium dioxide nanoparticles (TiO2 NPs) mitigated the negative effects of drought stress.•Calcium supplementation improved the growth and development of wheat plantsunder drought stress.•Combined application of TiO2 NPs and calcium improved all parameters under drought stress.
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