Triggering photocatalytic performance of La2CoxMn2-xO6 via heat activation.

The La-based perovskite (LaBO3) exhibits excellent optical properties. However, its valence band (VB) potential is not sufficiently positive to reach the oxidation potential required for the cleavage of chemical bonds (such as benzylic C-H), limiting its application in photocatalysis. Herein, we report the unconventional effects of heat activation on the reduction of the dissociation energy of benzylic C-H and aqueous H-O, thereby triggering the photocatalytic activity of La2CoxMn2-xO6 perovskites. Additionally, we demonstrate that photocatalysis is the main contributor to substrate conversion in the selective oxidation of toluene and reduction of CO2. Particularly, La2Co1.5Mn0.5O6 shows excellent performance with a product yield of 550.00 mmol gcat-1 and a toluene conversion of 22,866.67 µmol gcat-1 h-1. To the best of our knowledge, this is the highest reported product yield for the selective oxidation of benzylic C-H bond of toluene. Our findings provide insight into the specific role of heat activation in photocatalysis, which is crucial for breaking and overcoming the VB barrier to realize challenging reactions.

Water-solid contact electrification causes hydrogen peroxide production from hydroxyl radical recombination in sprayed microdroplets.

Contact electrification between water and a solid surface is crucial for physicochemical processes at water-solid interfaces. However, the nature of the involved processes remains poorly understood, especially in the initial stage of the interface formation. Here we report that H2O2 is spontaneously produced from the hydroxyl groups on the solid surface when contact occurred. The density of hydroxyl groups affects the H2O2 yield. The participation of hydroxyl groups in H2O2 generation is confirmed by mass spectrometric detection of 18O in the product of the reaction between 4-carboxyphenylboronic acid and 18O-labeled H2O2 resulting from 18O2 plasma treatment of the surface. We propose a model for H2O2 generation based on recombination of the hydroxyl radicals produced from the surface hydroxyl groups in the water-solid contact process. Our observations show that the spontaneous generation of H2O2 is universal on the surfaces of soil and atmospheric fine particles in a humid environment.

Efficient Photoreduction of CO2 to CO with 100% Selectivity by Slowing Down Electron Transport.

It remains challenging to obtain a single product in the gas-solid photocatalytic reduction of CO2 because CO and CH4 are usually produced simultaneously. This study presents the design of the I-type nested heterojunction TiO2/BiVO4 with controllable electron transport by modulating the TiO2 component. This study demonstrates that slowing electron transport could enable TiO2/BiVO4-4 to generate CO with 100% selectivity. In addition, modifying TiO2/BiVO4-4 by loading a Cu single atom further increased the CO product yield by 3.83 times (17.33 µmol·gcat-1·h-1), while maintaining 100% selectivity for CO. Characterization and density functional theory (DFT) calculations revealed that the selectivity was mainly determined by the electron transport of the support, whereas CO2 was efficiently adsorbed and activated by the Cu single atom. Such a two-step regulation strategy of combining heterojunction with single atom enhances the possibility of simultaneously obtaining high selectivity and high yield in the photocatalytic reduction of CO2.

Associations of Bisphenols Exposure and Hyperuricemia Based on Human Investigation and Animal Experiments.

Hyperuricemia is characterized by elevated blood uric acid (UA) levels, which can lead to certain diseases. Epidemiological studies have explored the association between environmental contaminant exposure and hyperuricemia. However, few studies have investigated the role of chemical exposure in the development of hyperuricemia. Here, we sought to investigate the effects of bisphenol exposure on the occurrence of hyperuricemia. Fifteen bisphenol chemicals (BPs) were detected in human serum and urine samples collected from an area with a high incidence of hyperuricemia in China. Serum UA levels positively correlated with urinary bisphenol S (BPS), urinary bisphenol P (BPP), and serum bisphenol F (BPF). The effects of these three chemicals on UA levels in mice were explored at various exposure concentrations. An increase in serum UA levels was observed in BPS- and BPP-exposed mice. The results showed that BPS exposure increased serum UA levels by damaging the structure of the kidneys, whereas BPP exposure increased serum UA levels by disturbing purine metabolism in the liver. Moreover, BPF did not induce an increase in serum UA levels owing to the inhibition of guanine conversion to UA. In summary, we provide evidence of the mechanisms whereby exposure to three BPs disturbs UA homeostasis. These findings provide new insights into the risks of exposure to bisphenol chemicals.

Comprehensive Toxicological Assessment of Halobenzoquinones in Drinking Water at Environmentally Relevant Concentration.

Halobenzoquinones (HBQs), an emerging unregulated category of disinfection byproduct (DBP) in drinking water, have aroused an increasing concern over their potential health risks. However, the chronic toxicity of HBQs at environmentally relevant concentrations remains largely unknown. Here, the occurrence and concentrations of 13 HBQs in drinking water from a northern megacity in China were examined using ultrahigh performance liquid chromatography coupled with triple-quadrupole tandem mass spectrometry (UHPLC-MS/MS). Four HBQs, including 2,6-dichloro-1,4-benzoquinone (2,6-DCBQ), 2,6-dibromo-1,4-benzoquinone (2,6-DBBQ), 2,3,6-trichloro-1,4-benzoquinone (TriCBQ), and 2,5-dibromo-1,4-benzoquinone (2,5-DBBQ), were detected beyond 50% occurrence frequency and at median concentrations from 4 to 50 ng/L. The chronic toxicity of these four HBQs to normal human colon and liver cells (FHC and THLE-2) was investigated at these concentrations. After 90 days of exposure, 2,5-DBBQ and 2,6-DCBQ induced the highest levels of oxidative stress and deoxyribonucleic acid (DNA) damage in colon and liver cells, respectively. Moreover, 2,5-DBBQ and 2,6-DCBQ were also found to induce epithelial-mesenchymal transition (EMT) in normal human liver cells via the extracellular signal regulated kinase (ERK) signaling pathway. Importantly, heating to 100 °C (boiling) was found to efficiently reduce the levels of these four HBQs in drinking water. These results suggested that environmentally relevant concentrations of HBQs could induce cytotoxicity and genotoxicity in normal human cells, and boiling is a highly efficient way of detoxification for HBQs.

Tailored Cl- Ligation on Supported Pt Catalysts for Selective Primary C-H Bond Oxidation.

It is challenging to achieve high selectivity over Pt-metal-oxide catalysts widely used in many selective oxidation reactions because Pt is prone to over-oxidize substrates. Herein, our sound strategy for enhancing the selectivity is to saturate the under-coordinated single Pt atoms with Cl- ligands. In this system, the weak electronic metal-support interactions between Pt atoms and reduced TiO2 cause electron extraction from Pt to Cl- ligands, resulting in strong Pt-Cl bonds. Therefore, the two-coordinate single Pt atoms adopt a four-coordinate configuration and thus inactivated, thereby inhibiting the over-oxidation of toluene over Pt sites. The selectivity for the primary C-H bond oxidation products of toluene was increased from 50.1 to 100%. Meanwhile, the abundant active Ti3+ sites were stabilized in reduced TiO2 by Pt atoms, leading to a rising yield of the primary C-H oxidation products of 249.8 mmol gcat-1. The reported strategy holds great promise for selective oxidation with enhanced selectivity.

Entropy-Driven Three-Dimensional DNA Nanofireworks for Simultaneous Real-Time Imaging of Telomerase and MicroRNA in Living Cells.

Real-time monitoring of different types of intracellular tumor-related biomarkers is of key importance for the identification of tumor cells. However, it is hampered by the low abundance of biomarkers, inefficient free diffusion of reactants, and complex cytoplasmic milieu. Herein, we present a stable and general method for in situ imaging of microRNA-21 and telomerase utilizing simple highly integrated dual tetrahedral DNA nanostructures (TDNs) that can naturally enter cells, which could initiate to form the three-dimensional (3D) higher-order DNA superstructures (DNA nanofireworks, DNFs) through a reliable target-triggered entropy-driven strand displacement reaction in living cells for remarkable signal amplification. Importantly, the excellent biostability, biocompatibility, and sensitivity of this approach benefited from (i) the precise multidirectional arrangement of probes with a pure DNA structure and (ii) the local target concentration enhanced by the spatially confined microdomain inside the DNFs. This strategy provides a pivotal molecular toolbox for broad applications such as biomedical imaging and early precise cancer diagnosis.

Surface Modification Determines the Distribution and Toxicity of Quantum Dots during the Development of Early Staged Zebrafish.

Surface modifications are generally used to functionalize QDots to improve their properties for practical applications, but the relationship between QDot modification and biological activity is not well understood. Using an early staged zebrafish model, we investigated the biodistribution and toxicity of CdSe/ZnS QDots with four types of modifications, including anionic poly(ethylene glycol)-carboxyl ((PEG)n-COOH), anionic mercaptopropionic acid (MPA), zwitterionic glutathione (GSH), and cationic cysteamine (CA). None of the QDots showed obvious toxicity to zebrafish embryos prior to hatching because the zebrafish chorion is an effective barrier that protects against QDot exposure. The QDots were mainly absorbed on the epidermis of the target organs after hatching and were primarily deposited in the mouth and gastrointestinal tract when the zebrafish started feeding. CA-QDots possessed the highest adsorption capacity; however, (PEG)n-COOH-QDots showed the most severe toxicity to zebrafish, as determined by mortality, hatching rate, heartbeat, and malformation assessments. It shows that the toxicity of the QDots is mainly attributed to ROS generation rather than Cd2+ release. This study provides a comprehensive understanding of the environmental and ecological risks of nanoparticles in relation to their surface modification.

Direct Uptake and Intracellular Dissolution of HgS Nanoparticles: Evidence from a Bacterial Biosensor Approach.

Mercury sulfide nanoparticles (HgSNPs), which occur widely in oxic and anoxic environments, can be microbially converted to highly toxic methylmercury or volatile elemental mercury, but it remains challenging to assess their bioavailability. In this study, an Escherichia coli-based whole-cell fluorescent biosensor was developed to explore the bioavailability and microbial activation process of HgSNPs. Results show that HgSNPs (3.17 ± 0.96 nm) trigger a sharp increase in fluorescence intensity of the biosensor, with signal responses almost equal to that of ionic Hg (Hg(II)) within 10 h, indicating high bioavailability of HgSNP. The intracellular total Hg (THg) of cells exposed to HgSNPs (200 µg L-1) was 3.52-8.59-folds higher than that of cells exposed to Hg(II) (200 µg L-1), suggesting that intracellular HgSNPs were only partially dissolved. Speciation analysis using size-exclusion chromatography (SEC)-inductively coupled plasma mass spectrometry (ICP-MS) revealed that the bacterial filtrate was not responsible for HgSNP dissolution, suggesting that HgSNPs entered cells in nanoparticle form. Combined with fluorescence intensity and intracellular THg analysis, the intracellular HgSNP dissolution ratio was estimated at 22-29%. Overall, our findings highlight the rapid internalization and high intracellular dissolution ratio of HgSNPs by E. coli, and intracellular THg combined with biosensors could provide innovative tools to explore the microbial uptake and dissolution of HgSNPs.

Obesogenic effect of Bisphenol P on mice via altering the metabolic pathways.

Bisphenol P (BPP), structurally similar to bisphenol A, is commonly identified in the samples of environment, food, and humans. Unfortunately, very little information is currently available on adverse effects of BPP. The obesogenic effects and underlying mechanisms of BPP on mice were investigated in this study. Compared with the control, high-resolution microcomputed tomography (micro-CT) scans displayed that the visceral fat volume of mice was significantly increased at a dose of 5 mg/kg/day after BPP exposure for 14 days, whereas the subcutaneous fat volume remained unchanged. Nontargeted metabolomic analysis revealed that BPP significantly perturbed the metabolic pathways of mouse livers, and acetyl-CoA was identified as the potential key metabolite responsible for the visceral fat induced by BPP. These findings recommend that a great deal of attention should be paid to the obesogenic properties of BPP as a result of its widely utilized and persistence in the environment.

A sustained-release microcarrier effectively prolongs and enhances the antibacterial activity of lysozyme.

Bacterial infections have become a great threat to public health in recent years. A primary lysozyme is a natural antimicrobial protein; however, its widespread application is limited by its instability. Here, we present a poly (N-isopropylacrylamide) hydrogel inverse opal particle (PHIOP) as a microcarrier of lysozyme to prolong and enhance the efficiency against bacteria. This PHIOP-based lysozyme (PHIOP-Lys) formulation is temperature-responsive and exhibits long-term sustained release of lysozyme for up to 16 days. It shows a potent antibacterial effect toward both Escherichia coli and Staphylococcus aureus, which is even higher than that of free lysozyme in solution at the same concentration. PHIOPs-Lys were demonstrated to effectively inhibit bacterial infections and enhance wound healing in a full-thickness skin wound rat model. This study provides a novel pathway for prolonging the enzymatic activity and antibacterial effects of lysozyme.

Association between serum levels of TSH and free T4 and per- and polyfluoroalkyl compounds concentrations in pregnant women.

Many per- and polyfluoralkyl substances (PFASs) may disrupt maternal thyroid hormone homeostasis in pregnancy. Concerns should be raised regarding the PFASs exposure in pregnant women because thyroid hormones are involved in the early development of the fetus. In this study, we measured the concentrations of 13 PFASs, including five novel short-chain PFASs, in serum from 123 pregnant women in Beijing, China. Linear regression models were used to investigate the association between thyroid-stimulating hormone (TSH) or free thyroxine (FT4) levels and PFASs concentrations under consideration of the impacts of pregnancy-induced physiological factors. We found that perfluorobutanoic acid (PFBA) (ß=0.189, 95%CI=-0.039, 0.417, p=0.10) and perfluorodecanoic acid (PFDA) (ß=-0.554, 95%CI=-1.16, 0.049, p=0.071) were suggestive of significant association with TSH in thyroid peroxidase antibody (TPOAb) negative women. No association was observed between all PFASs and FT4 levels after controlling for these confounding factors, such as BMI, gestational weight gain and maternal age. These findings suggest that it should pay more attention to the association between thyroid hormone levels and short-chain PFASs concentrations. Future studies could consider a greater sample and the inclusion of other clinical indicators of thyroid function, such as free T3 and total T3.

Silver Nanoparticles Induce Apoptosis in HepG2 Cells through Particle-Specific Effects on Mitochondria.

Silver nanoparticles (AgNPs) have been widely used in biomedical and consumer products. It remains challenging to distinguish the toxicity of AgNPs derived from the particle form or the released silver ions (Ag+). In this study, the toxic effects of two citrate-coated AgNPs (20 and 100 nm) and Ag+ were investigated in hepatoblastoma cells (HepG2 cells). The suppression tests showed that AgNPs and Ag+ induced cell apoptosis via different pathways, which led us to speculate on the AgNP-induced mitochondrial damage. Then, the mitochondrial damages induced by AgNPs and Ag+ were compared under the same intracellular Ag+ concentration, showing that the mitochondrial damage might be mainly attributed to Ag nanoparticles but not to Ag+. The interaction between AgNPs and mitochondria was analyzed using a scattered light imaging method combined with light intensity profiles and transmission electron microscopy. The colocalization of AgNPs and mitochondria was observed in both NP20- and NP100-treated HepG2 cells, indicating a potential direct interaction between AgNPs and mitochondria. These results together showed that AgNPs induced apoptosis in HepG2 cells through the particle-specific effects on mitochondria.

Particle-Bound Hg(II) is Available for Microbial Uptake as Revealed by a Whole-Cell Biosensor.

Particle-bound mercury (HgP), ubiquitously present in aquatic environments, can be methylated into highly toxic methylmercury, but it remains challenging to assess its bioavailability. In this study, we developed anEscherichia coli-based whole-cell biosensor to probe the microbial uptake of inorganic Hg(II) and assess the bioavailability of HgP sorbed on natural and model particles. This biosensor can quantitatively distinguish the contribution of dissolved Hg(II) and HgP to intracellular Hg. Results showed that the microbial uptake of HgP was ubiquitous in the environment, as evidenced by the bioavailability of sorbed-Hg(II) onto particulate matter and model particles (Fe2O3, Fe3O4, Al2O3, and SiO2). In both oxic and anoxic environments, HgP was an important Hg(II) source for microbial uptake, with enhanced bioavailability under anoxic conditions. The composition of particles significantly affected the microbial uptake of HgP, with higher bioavailability being observed for Fe2O3 and lower for Al2O3 particles. The bioavailability of HgP varied also with the size of particles. In addition, coating with humic substances and model organic compound (cysteine) on Fe2O3 particles decreased the bioavailability of HgP. Overall, our findings highlight the role of HgP in Hg biogeochemical cycling and shed light on the enhanced Hg-methylation in settling particles and sediments in aquatic environments.

Administration of Silver Nasal Spray Leads to Nanoparticle Accumulation in Rat Brain Tissues.

The use of commercial products containing engineered nanomaterials in realistic scenarios may lead to the accumulation of exogenous particles in brain tissues. In this study, we simulated the use of silver (Ag) nasal spray in humans using Sprague-Dawley rats at 0.04 mg/kg/day. Silver-containing particles were explicitly identified in the rat brain after the administration of nasal sprays containing colloidal Ag or silver ions (Ag+) for 2 weeks using multiple methods. The accumulation of Ag-containing particles showed a delayed effect in different brain regions of the rats, with the mass concentration of particles increasing continuously for 1-2 weeks after the termination of administration. The size of the observed Ag-containing particles extracted from the brain tissues ranged from 18.3 to 120.4 nm. Further characterization by high-resolution transmission electron microscopy with energy-dispersive spectroscopy showed that the nanoparticles comprised both Ag and sulfur (S), with Ag/S atomic ratios of 1.1-7.1, suggesting that Ag-containing particles went through a series of transformations prior to or during their accumulation in the brain. Collectively, these findings provide evidence for the accumulation and transformation of Ag-containing particles in the rat brain, indicating a realistic risk to brain health resulting from the application of Ag-containing commercial products.

Passive Smoking Exposure Modifies Cardiovascular Structure and Function: Beijing Child Growth and Health Cohort (PROC) Study.

Passive smoking exposure in children is prevalent worldwide and exposes children to respiratory and systemic toxins. In this study, we enrolled 568 children to study how secondhand smoke (SHS) might affect children's cardiovascular health in China. The measurement of nicotine and its metabolites in urine showed that 78.9% of children were exposed to SHS. Children exposed to SHS had greater interventricular septum thickness (p = 0.005) and left ventricular mass index (p = 0.008) than nonexposed children. Urinary norcotinine levels were associated with increased ascending aorta diameter (ß = 0.10, 95%CI 0.02-0.17) and decreased left ventricular end systolic diameter (ß = -0.10, 95%CI -0.19 to -0.01). The effects of SHS exposure on cardiovascular function: norcotinine levels associated with lower left ventricular mass index (ß = -0.32, 95%CI -0.59 to -0.05), left ventricular end diastolic volume index (ß = -0.43, 95%CI -0.85 to -0.02), and left ventricular end systolic volume index (ß = -0.20, 95%CI -0.37 to -0.03). Moreover, there no no significant associations of nicotine, cotinine, and trans-3'-hydroxycotinine with cardiovascular health. Overall, SHS exposure in children remains prevalent in Beijing and may affect children's cardiovascular development, in both structure and function. It suggests that stricter and practical measures are needed toward the elimination of tobacco use in children's environments.

Effect-Directed Analysis Based on the Reduced Human Transcriptome (RHT) to Identify Organic Contaminants in Source and Tap Waters along the Yangtze River.

Since a large number of contaminants are detected in source waters (SWs) and tap waters (TWs), it is important to perform a comprehensive effect evaluation and key contributor identification. A reduced human transcriptome (RHT)-based effect-directed analysis, which consisted of a concentration-dependent RHT to reveal the comprehensive effects and noteworthy pathways and systematic identification of key contributors based on the interactions between compounds and pathway effects, was developed and applied to typical SWs and TWs along the Yangtze River. By RHT, 42% more differentially expressed genes and 33% more pathways were identified in the middle and lower reaches, indicating heavier pollution. Hormone and immune pathways were prioritized based on the detection frequency, sensitivity, and removal efficiency, among which the estrogen receptor pathway was the most noteworthy. Consistent with RHT, estrogenic effects were widespread along the Yangtze River based on in vitro evaluations. Furthermore, 38 of 100 targets, 39 pathway-related suspects, and 16 estrogenic nontargets were systematically identified. Among them, diethylstilbestrol was the dominant contributor, with the estradiol equivalent (EEQ) significantly correlated with EEQwater. In addition, zearalenone and niclosamide explained up to 54% of the EEQwater. The RHT-based EDA method could support the effect evaluation, contributor identification, and risk management of micropolluted waters.

A single-cell survey unveils cellular heterogeneity and sensitive responses in mouse cortices induced by oral exposure to triphenyl phosphate.

Triphenyl phosphate (TPhP) is a non-halogenated organophosphorus flame retardant, and there is a higher exposure risk in children. TPhP has been found to be neurotoxic upon developmental exposure, yet the specific mechanism remains unclear. To characterize the cellular responses underlying TPhP-induced developmental neurotoxicity, we administered TPhP (0.5, 5 or 50 mg/kg/day) to neonatal mice from postnatal day 10 (P10)-P70. A total of 17,229 cells and 26,338 genes were identified in cortical samples from control and low-dose (the internal doses of metabolite DPhP comparable to human exposure level) groups using single-cell RNA sequencing (scRNA-seq). TPhP exposure led to heterogeneous transcriptional alterations and intercellular crosstalk among neurons, neural stem/progenitor cells (NSPCs), endothelial cells, and immunocytes. Deprivation of NSPCs, loss of mature neurons, and concomitant neuroinflammation mediated by extrinsic and intrinsic immunocytes were found in TPhP-exposed cortices. In addition, we observed blood-brain barrier destruction prior to the anxiety/depression-like neurobehavioral changes. These results reveal the distinctive cellular processes in TPhP's neurodevelopmental toxicity and uncover that the impeded neurogenesis, disrupted vascular barrier, and concomitant neuroinflammation are the sensitive responses to TPhP exposure. Our study paves the way for the application of scRNA-seq in toxicity assessments for emerging neurotoxic pollutants.

In situ High-Throughput Single-Cell Analysis Reveals the Crosstalk between Nanoparticle-Induced Cell Responses.

Nanomaterials are widely used in a variety of industrial, biological, and medical applications. Therefore, high concerns about their possible impact on human and environmental health have been raised. Here, we describe a high-throughput single-cell imaging method to reveal the crosstalk among quantum dot (QDot)-induced ROS generation, apoptosis, and changes in nucleus size in macrophages. In triple marker combinations, we assessed the correlations of three QDot-induced cellular responses via divided subsets based on single-cell analysis. In contrast to the results obtained from the cell population, we demonstrated that the change in nucleus size was positively correlated with ROS generation. We found that QDot exposure induced ROS generation, which led to cell apoptosis, followed by a change in nucleus size. In general, these observations on crosstalk of cellular responses provide detailed insights into the heterogeneity of nanoparticle exposure.

Dark Reduction of Mercury by Microalgae-Associated Aerobic Bacteria in Marine Environments.

Redox transformation of mercury (Hg) is critical for Hg exchange at the air-sea interface and it can also affect the methylation of Hg in marine environments. However, the contributions of microalgae and aerobic bacteria in oxic seawater to Hg2+ reduction are largely unknown. Here, we studied the reduction of Hg2+ mediated by microalgae and aerobic bacteria in surface marine water and microalgae cultures under dark and sunlight conditions. The comparable reduction rates of Hg2+ with and without light suggest that dark reduction by biological processes is as important as photochemical reduction in the tested surface marine water and microalgae cultures. The contributions of microalgae, associated free-living aerobic bacteria, and extracellular substances to dark reduction were distinguished and quantified in 7 model microalgae cultures, demonstrating that the associated aerobic bacteria are directly involved in dark Hg2+ reduction. The aerobic bacteria in the microalgae cultures were isolated and a rapid dark reduction of Hg2+ followed by a decrease of Hg0 was observed. The reduction of Hg2+ and re-oxidation of Hg0 were demonstrated in aerobic bacteria Alteromonas spp. using double isotope tracing (199Hg2+ and 201Hg0). These findings highlight the importance of algae-associated aerobic bacteria in Hg transformation in oxic marine water.