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.

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.

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.

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.

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.

Scattered Light Imaging Enables Real-Time Monitoring of Label-Free Nanoparticles and Fluorescent Biomolecules in Live Cells.

Simultaneously monitoring label-free nanoparticles (NPs) and fluorescent biomolecules inside the live cell in real time is challenging because both imaging methods require different instrumentation and measuring principles. Here we report a novel scattered light imaging (SLi) technique that allows label-free NPs to be monitored using a conventional confocal microscope. The method shows a high spatial resolution and can distinguish label-free silver nanoparticles (AgNPs) with a 10 nm size difference in live cells. We performed SLi to observe the uptake, movement, distribution, and transformation of AgNPs in live cells at a single-particle level. The method is applicable to accurately track the localization of a variety of nanomaterials inside the cell. With this approach, label-free NP and fluorescent-labeled biomolecules are imaged simultaneously making it possible to real-time monitor nanobio interactions.

Ultralong AgNWs-induced toxicity in A549 cells and the important roles of ROS and autophagy.

Safety concerns have been raised with regard to silver nanowires (AgNWs) because of their extensive applications. Recently, ultralong AgNWs have shown physical properties superior to those of short AgNWs. However, little is known about their toxicity and potential risks. In this study, we demonstrated a series of ultralong AgNWs-induced biological effects in human lung cancer epithelial cells (A549). Ultralong AgNWs treatments induced ROS generation, mitochondria-mediated apoptosis, and self-protective autophagy at nonlethal concentrations. In contrast to some previous reports, apoptosis was found not to correlate with the reduction of intracellular ROS. Measuring the processing of ROS generation, apoptosis and autophagy, we demonstrated that ROS not only enhance mitochondrial damage, but also raise protective autophagic flux in ultralong AgNW-treated cells. Moreover, ultralong AgNWs were found to be internalized into the cytoplasm of the epithelial cells. This study not only investigates ultralong AgNWs-induced cytotoxicity but also pinpoints ROS as a key signal in mechanisms of their toxicity.

Effects of environmental contaminants on fertility and reproductive health.

Recent research indicates that the human infertility rate is increasing. Although various reasons have been hypothesized for the growing infertility rate, environmental contaminants are potentially important causal agents associated with this change. Chemical contaminants are widespread throughout our environment and human exposure is virtually unavoidable. The overall contribution of environmental exposure to infertility is unknown, but studies involving occupational exposure, together with results from animal experiments, suggest that environmental contaminants may adversely affect fertility. We reviewed the adverse effects of environmental exposure on fertility and related reproductive outcomes. Environmental contaminants covered in this review include heavy metals, organic solvents, pesticides and endocrine disrupting chemicals. It is hoped that this review will highlight the need for further research in this area.

Oxidative stress and cytotoxicity induced by tetrachlorobisphenol A in Saccharomyces cerevisiae cells.

Tetrachlorobisphenol A (TCBPA), which is widely used as flame retardant, can be released into various environments, thereby being absorbed by wildlife or human beings through food chain's bio-magnification and causing some adverse influences on wildlife or human beings. However, limited data are currently available on TCBPA-associated cytotoxicity and related mechanisms. Here, the cytotoxicity induced by different concentrations of TCBPA (i.e., 5, 10 and 20 µM) was studied using Saccharomyces cerevisiae, a simple eukaryotic model organism. TCBPA treatment inhibited the growth and survival rate of yeast cell in a dose-dependent manner. Moreover, TCBPA promoted the increasing of intracellular oxidative stress by enhancing accumulation of intracellular reactive oxygen species (ROS). Meanwhile, lipid peroxidation degree (represented by malondialdehyde (MDA) content) and DNA damage degree (represented by 8-hydroxy deoxyguanosine (8-oxodG) content) in yeast cell also increased after TCBPA treatment. However, yeast cell mitochondrial membrane potential (Δψm) decreased after TCBPA treatment. It was noteworthy that there was no significant inhibitory effect on yeast cell growth or survival rate in 5 µM TCBPA-treated cells, but the intracellular MDA content and Δψm level changed significantly, suggesting the potential cell damage secondary to the relative low dose of TCBPA exposure. Results presented here would highlight our knowledge about TCBPA-associated cytotoxicity in organisms.

Determining the Cytotoxicity of Rare Earth Element Nanoparticles in Macrophages and the Involvement of Membrane Damage.

Rare earthelement nanomaterials (REE NPs) hold considerable promise, with high availability and potential applications as superconductors, imaging agents, glass additives, fertilizers additives and feed additives. These results in potential REE NP exposure to humans and the environment through different routes and adverse effects induced by biological application of these materials are becoming an increasing concern. This study investigates the cytotoxicity of REE NPs: nLa2O3, nEu2O3, nDy2O3 and nYb2O3 from 2.5 to 80 µg/mL, in macrophages. A significant difference was observed in the extent of cytotoxicity induced in macrophages by differential REE NPs. The high-atomic number materials (i.e., nYb2O3) tending to be no toxic whereas low-atomic number materials (nLa2O3 and nEu2O3 and nDy2O3) induced 75.1%, 53.6% and 20.7% dead cells. With nLa2O3 as the representative material, we demonstrated that nLa2O3 induced cellular membrane permeabilization, through the sequestration of phosphates from membrane. The further mechanistic investigation established that membrane damage induced intracellular calcium increased to 3.0- to 7.3-fold compared to control cells. This caused the sustained overload of mitochondrial calcium by approximately 2.4-fold, which regulated cell necrosis. In addition, the injury of cellular membrane led to the release of cathepsins into cytosol which also contributed to cell death. This detailed investigation of signaling pathways driving REE NP-induced toxicity to macrophages is essential for better understanding of their potential health risks to humans and the environment.

Experimental and computational insights on the recognition mechanism between the estrogen receptor α with bisphenol compounds.

Certain bisphenols (BPs) have been regarded as endocrine-disrupting chemicals due to their structural similarities to bisphenol A (BPA), a well-known weak estrogenic chemical. However, very limited data are currently available on the relationship between estrogenic activity and the structure of BP analogs. Therefore, we systematically investigated the estrogenic potency of 14 selected BP analogs with typical structures using experimental and computational methods. Most of the tested BP analogs exhibited weak estrogenic activities in both cell proliferation and MVLN assays with the exception of TBBPA, TCBPA and TBBPS. Molecular modeling techniques have been performed to investigate the dynamic structural characteristics of recognition processes between BPs and estrogen receptor α (ERα) at the atomic level. Thr347 was identified as the key residue responsible for the recognition of TBBPA, TCBPA and TBBPS by means of induced-fit H-bonding interactions in the binding pocket of ERα, whereas other BPs, in turn, rely on the alternative formation of H-bonds with His524. Subsequent allosteric modulation interferes significantly with the stability of helix 12 that is crucial for the transcriptional activity of ERα. These structural perturbations that are induced by the three compounds were further confirmed to reduce the recruitment potency of co-activators more than other BPs based on calculations of binding free energies, which is in line with observed experimental transcriptional activities. Our findings may help to elucidate the estrogenic potency of BPs with different molecular structures.

Tetrachloro-1,4-benzoquinone induces apoptosis of mouse embryonic stem cells.

Pentachlorophenol (PCP) is a widespread, persistent environmental contaminant, and it is enzymatically activated to form a reactive metabolite, tetrachloro-1,4-benzoquinone (TCBQ). To our knowledge, there is no information about TCBQ toxicity on embryonic stem cells. Here, we demonstrated that TCBQ induced significantly apoptosis of mouse embryonic stem cells in a concentration-dependent manner. We also showed that TCBQ elevated genomic 5-hydroxymethylcytosine (5hmC) by affecting ten-eleven translocation (Tet) dioxygenases in mouse embryonic stem cells. We further investigated whether Tet dioxygenases were implicated in TCBQ-induced apoptosis. By depleting all three dioxygenases (Tet1-3), we found that Tet dioxygenases slightly inhibited both early and late apoptosis induced by TCBQ at a low concentration (30µmol/L). Meanwhile, treated by TCBQ at higher concentrations (40 and 50µmol/L), the total percentage of apoptotic cells was not affected by Tet dioxygenases. However, Tet dioxygenases tended to arrest mouse ES cells to be at early apoptotic stage and to reduce the cells to enter later apoptotic stage. These results indicate that Tet dioxygenases play a role in shaping TCBQ-induced apoptosis in mouse embryonic stem cells. Our study provides new insights into the toxicology of PCP and its reactive metabolite TCBQ.

Co-exposure of carboxyl-functionalized single-walled carbon nanotubes and 17α-ethinylestradiol in cultured cells: effects on bioactivity and cytotoxicity.

17α-Ethinylestradiol (EE2) is the representative of environmental estrogens. Although EE2 can interact with some engineered nanoparticles (NPs), little is known about the bioactivity of NP-associated EE2 in organisms. In this study, we investigated the combined effects of the co-exposed carboxyl-functionalized single-walled carbon nanotubes (cf-SWCNTs) and EE2 in the human breast adenocarcinoma cell line (MCF-7 cells), focusing on the cytotoxicity and bioactivity. There were no significant differences in mitochondrial activity, membrane damage, and cell apoptosis when exposed to cf-SWCNTs with and without adsorbed EE2. However, the bioactivity of adsorbed EE2 on cf-SWCNTs was significantly inhibited. The calculated effective concentration of EE2 in cultured cells showed that less than 0.2% of the total adsorbed EE2 was released, indicating that most EE2 was retained on the cf-SWCNTs during cellular exposure. Furthermore, there were no obvious changes in the bioactivity of adsorbed EE2 in the culture medium containing 5-20% fetal bovine serum (FBS), even up to 10 days of incubation, indicating that the adsorbed EE2 on cf-SWCNTs is highly stable in the cell culture medium. These results mark a promising possibility for EE2 to be adsorbed by cf-SWCNTs in environmentally relevant settings and thereby influenced its toxicity and biological fate. This is also tempting for future studies involving risk assessment ways for association between NPs and contaminants in the environment.

Effects of oilfield-produced water discharge on the spatial patterns of microbial communities in arid soils.

Recently intensified oil exploitation has resulted in the discharge of large amounts of wastewater containing high concentrations of organic matter and nutrients into the receiving aquatic and soil environments; however, the effects of oilfield-produced water on the soil microbiota are poorly understood. In this study, we conducted a comprehensive analysis to reveal the composition and diversity of the microbial community at horizontal and vertical scales in a typical arid soil receiving oilfield-produced water in Northwest China. Oilfield-produced water caused an increase in microbial diversity at the horizontal scale, and the communities in the topsoil were more variable than those in the subsoil. Additionally, the microbial taxonomic composition differed significantly between the near- and far-producing water soils, with Proteobacteria and Halobacterota dominating the water-affected and reference soil communities, respectively. Soil property analysis revealed that pH, salt, and total organic content influenced the bacterial communities. Furthermore, the oil-produced water promoted the complexity and modularity of distance-associated microbial networks, indicating positive interactions for soil ecosystem function, but not for irrigation or livestock watering. This is the first detailed examination of the microbial communities in soil receiving oilfield-produced water, providing new insights for understanding the microbial spatial distributions in receiving arid soils.

Chronic exposure to polystyrene microplastics increased the chemosensitivity of normal human liver cells via ABC transporter inhibition.

Microplastics (MPs) are ubiquitous in environmental compartments and consumer products. Although liver is frequently reported to be a target organ of MP accumulation in mammals, few studies have focused on MP hepatoxicity in humans. In this study, we used normal human liver cells, THLE-2, to assess the acute and chronic toxicity of polystyrene (PS) MPs with sizes of 0.1 and 1 µm. The results showed that after 48 h of exposure, both kinds of PS MPs could enter THLE-2 cells and cause no obviously acute cytotoxicity at <20 µg/mL. In contrast, metabolomic analysis revealed that 90 days of PS MPs exposure at environmentally relevant dose (0.2 µg/mL) could significantly alter the metabolic profiles of the cells, especially the nanosized MPs. KEGG pathway analysis showed that the ATP-binding cassette (ABC) transporter pathway was the most significantly changed pathway. Cell functional tests confirmed that chronic PS MP treatment could inhibit the activity of the ABC efflux transporter and further increase the cytotoxicity of arsenic, indicating that the PS MPs had a chemosensitizing effect. These findings underline the chronic risk of MPs to human liver.

Special Distribution of Nanoplastics in the Central Nervous System of Zebrafish during Early Development.

There is growing concern about the distribution of nanoplastics (NPs) in the central nervous system (CNS), whereas intrusion is poorly understood. In this study, fluorescent-labeled polystyrene NPs (PS-NPs) were microinjected into different areas of zebrafish embryo to mimic different routes of exposure. PS-NPs were observed in the brain, eyes, and spinal cord through gametal exposure. It indicated that maternally derived PS-NPs were specially distributed in the CNS of zebrafish during early development. Importantly, these NPs were stranded in the CNS but not transferred to other organs during development. Furthermore, using neuron GFP-labeled transgenic zebrafish, colocalization between NPs and the neuron cells revealed that NPs were mostly enriched in the CNS surrounded but not the neurons. Even so, the intrusion of NPs into the CNS induced the significant upregulation of some neurotransmitter receptors, leading to an inhibited effect on the movement of zebrafish larvae. This work provides insights into understanding the intrusion and distribution of NPs in the CNS and the subsequent potential adverse effects.

Spatial nanopores promote laccase degradation of bisphenol A and its analogs.

Bisphenol A (BPA) and its analogs are endocrine-disrupting chemicals that are frequently detected in environmental and human samples. However, the effective removal of BPA and its analogs has not yet been extensively studied. Herein, we introduce a novel enzyme reactor for the degradation of BPA and its analogs in water. The influence of pore size on the degradation efficiency of immobilized laccase in the spatial nanopores of hydrogel was investigated using BPA as a representative compound. This showed that nanopores enhance the activity of immobilized laccases in a pore size-dependent manner and increase their stability. Compared with the same amount of free laccase, the 50 mg/L BPA degradation performance of laccase immobilized in 76 nm nanopores increased to 300 %. Taking advantage of magnetic separation, this immobilized laccase can be reused, and its degradation capacity was maintained at over 73.7 % after ten reactions. Moreover, the degradation of seven BPA analogs was 1.03-5.88 times higher using laccase immobilized in nanopores compared with free laccase. Also, the biocatalyst could efficiently degrade BPA analogs in real water matrix. This study opens up a new avenue for the removal of BPA and its analogs by immobilizing laccase in nanopores, overcoming the key limitations introduced by the short enzyme life span and non-reusability.

Microalgae-derived carbon quantum dots mediated formation of metal sulfide nano-adsorbents with exceptional cadmium removal performance.

Metal sulfides are regarded as efficient scavengers for heavy metals. However, the heavy metal adsorption capacity of metal sulfides is far from its theoretical values due to the insufficient exposure of adsorption sites. Surface modification of metal sulfides is considered one of the most effective strategies for improving heavy metal removal performance. Here, microalgae-derived carbon quantum dots (CQDs) were used as a green modifier for mediating nano-MnS/FeS formation to enhance Cd2+ removal. With the addition of 1 wt% CQDs, the Cd2+ adsorption capacity of 1 %CQDs-MnS reached 481 mg/g at 25 °C and 648.6 mg/g at 45 °C, which surpassed most of the previously reported metal sulfides. Furthermore, the CQDs-modified MnS displayed a better Cd2+ removal capacity than the commercial modifier sodium alginate. The mechanism analysis suggested that decreasing the particle size to expose more adsorption sites and providing additional chelating sites derived from the CQDs are two main reasons why CQDs enhance the Cd2+ adsorption capacity of metal sulfides. This study presents an exceptional cadmium nano-adsorbent of 1 %CQDs-MnS and provides a new perspective on the enhancement of heavy metal removal by using CQDs as a promising and universal green modifier that mediates the formation of metal sulfides.

Rapid and simultaneous determination of multiple endocrine-disrupting chemicals and their metabolites in human serum and urine samples.

Bisphenols, parabens, and their metabolites are a group of chemical compounds with a wide range of polarities but similar chemical structures, which presents a challenge for the simultaneous determination of these compounds in complex biological samples. In this study, a rapid and sensitive method for simultaneous quantification of free bisphenol A (BPA), conjugated BPA, bisphenols, and parabens analogs was developed using solid-phase extraction (SPE) tandem liquid-liquid extraction (LLE). We compared the effects of different types of SPE cartridges, diluents, and LLE solvents on the analyte recovery. Utilizing the direct and indirect determination methods (enzyme hydrolysis), we confirmed the accuracy of the direct method for measuring BPA glucuronide and BPA disulfate. The method enabled the analysis of 24 endocrine-disrupting chemicals (EDCs) in one injection through UHPLC-MSMS measurements, with satisfactory recovery (mean: 91.8-98.6% for urine, 80.2%-96.8% for serum) and precision (RSD <15%). The LOD and LOQ values were 0.003 and 0.01 ng/mL for serum, and 0.002 and 0.006 ng/mL for urine samples, respectively. For real sample analysis, the median concentration of analytes in serum and urine samples ranged from 0.04 ng/mL (BPS) to 56.4 ng/mL (4-HB) and 0.11 ng/mL (BPA) to 136 ng/mL (4-HB), respectively. This method provides a new strategy to simultaneously identify compounds with a wide range of polarities from complicated biological matrices.