Characterization, hazard identification, and risk assessment of volatile organic compounds in Poly(butylene adipate-co-terephthalate)-based food contact articles.

The chemical safety of poly (butylene adipate-co-terephthalate) (PBAT) based food contact articles (FCAs) has aroused increasing toxicological concerns in recent years, but the chemical characterization and associated risk assessment still remain inadequate as it fails to elucidate the distribution pattern and discern the potential genotoxic and carcinogenic hazards of the identified substances. Herein, the volatile organic compounds (VOCs) in 50 batches of PBAT-based FCAs of representative categories and 10 batches of PLA and PBAT pellets were characterized, by which 237 VOCs of 10 chemical categories were identified and exhibited characteristic distribution patterns in the chemical spaces derived from their molecular descriptors. Chemical hazards associated with the identified VOCs were discerned by a hazard-driven classification scheme integrating hazard-related knowledge from multiple publicly available sources, and 34 VOCs were found to bear genotoxic or carcinogenic hazards and to feature higher average molecular weight than the other VOCs. Finally, the Risk and hazard quotient (HQ) calculated as the metrics of risk suggested that all identified VOCs posed acceptable risks (Risk<10-4 or HQ < 1), whereas oxolane, butyrolactone, N,N-dimethylacetamide, 2-butoxyethanol, benzyl alcohol, and 1,2,3-trichloropropane posed non-negligible (Risk>10-6) genotoxic or carcinogenic risk and thus should be of prioritized concern to promote the chemical safety of PBAT-based FCAs.

[Spherical amino-functionalized covalent organic frameworks: Synthesis and adsorption performance toward perfluorinated compounds].

Perfluorinated compounds (PFCs) are widely used in textiles, fire protection, metal electroplating, and semiconductor production owing to their hydrophobic and oil-repellent characteristics. However, they are also persistent organic pollutants. The uncontrolled discharge of PFCs into the environment has led to serious global pollution. PFCs pose severe reproductive, neural, immune, and other threats to human health by accumulating through the food chain. Thus, the development and application of high-performance extraction materials has become a research hotspot in efforts to achieve the accurate detection of trace PFCs in environmental waters. Most traditional PFC adsorbents present a number of disadvantages, such as low adsorption selectivity, slow diffusion, and poor reusability. Covalent organic frameworks (COFs) are crystalline polymers with ordered porous structures, large specific surface areas, and high chemical and thermal stability. These frameworks can easily be functionalized for the desired purpose. In this paper, spherical amino-functionalized COFs (denoted COF-NH2) were fabricated via a two-step method to effectively enrich/remove PFCs from water. First, vinyl covalent organic framework (Vinyl COF) was synthesized at room temperature using 1,4-diradical-2,5-divinylbenzene (Dva) and 1,3,5-tris(4-aminophenyl)benzene (Tab) as building blocks. Then, thioether-bridged aromatic amine-functionalized spherical COF-NH2 was synthesized through a thiol-alkenyl click reaction using 4-aminothiophenol as the functional monomer. COF-NH2 showed good dispersion in water owing to its abundant amino groups, forming multiple hydrogen bonds with the F atoms of PFCs. The synergistic hydrophobic interactions between the organic skeleton of the COF and alkyl carbon chains of the PFCs led to enhanced adsorption efficiency. The produced Vinyl COF and COF-NH2 were characterized by Fourier transform infrared spectroscopy (FT-IR), field-emission scanning electron microscopy (SEM), powder X-ray diffraction (PXRD), thermogravimetric analysis (TGA), and Brunner-Emmet-Teller (BET) measurements. The results confirmed that spherical COF-NH2 materials with a homogeneous size distribution were successfully fabricated. The obtained COF-NH2 microspheres had a diameter of approximately 500 nm and exhibited high thermal stability as well as a large specific surface area and pore volume. The adsorption kinetics, isotherm adsorption models, pH effects, and regeneration properties of COF-NH2 were also investigated, and the results indicated that the adsorption of PFCs by COF-NH2 conformed to the pseudo-second-order kinetic and Langmuir isotherm adsorption models. The obtained COF-NH2 microspheres can be applied over a wide pH range, and the best adsorption effect was achieved in neutral and alkaline environments. After five cycles of regeneration and reuse, the COF-NH2 microspheres retained their good adsorption efficiency for PFCs. The adsorption mechanism was mainly attributed to the synergistic effect of hydrogen bonding and hydrophobic interactions between COF-NH2 and the PFCs. The extraction efficiencies of the microspheres toward five PFCs (perfluorobutyric acid, perfluorovaleric acid, perfluorohexanoic acid, perfluorooctanoic acid, and perfluorononanoic acid) in tap and Pearl River water samples were between 91.76% and 98.59%, with relative standard deviations (RSDs) (n=3) varying from 0.82% to 3.8%; these findings indicate that the obtained COF-NH2 is promising for the extraction of PFCs from complex water samples. Given their uniform size distribution, high thermal stability, good adsorption performance, and reusability, the novel spherical COF-NH2 materials developed in this study may be used as solid-phase extraction materials or filled into liquid chromatographic columns for the enrichment, separation, and detection of PFCs in complex samples.

"Two-in-one" dual-function luminescent MOF hydrogel for onsite ultra-sensitive detection and efficient enrichment of radioactive uranium in water.

In consideration of the severe hazards of radioactive uranium pollution and the growing demand of uranium resources, the novel sensor/adsorbent composite was creatively developed to integrate the dual functions for on-site detection of uranium contamination and efficient recovery of uranium resources. By hybridizing the luminescent 3D terbium (III) metal-organic framework (Tb-MOF) with sodium alginate (SA) gel using terbium (III) as cross-linker, the Tb-MOF/Tb-AG was fabricated with multi-luminescence centers and sufficient binding sites for uranium. Notably, the ultra-high sensitivity with detection limit as low as 1.2 ppt was achieved, which was 4 orders of magnitude lower than the uranium contamination standard in drinking water (USEPA) and even comparable to the sensitivity of the ICP-MS. Furthermore, the very wide quantification range (1.0 ×10-9-5.0 ×10-4 mol/L), remarkable adsorption capacity (549.0 mg/g) and outstanding anti-interference ability have been achieved without sophisticated sample preparation procedures. Applied in complex natural water samples from Uranium Tailings and the Pearl River, this method has shown good detection accuracy. The ultra high sensitivity and great adsorption capacity for uranium could be ascribed to the synergistic coordination, hydrogen bonding and ion exchange between uranium and Tb-MOF/Tb-AG. The mechanisms were explored by infrared spectroscopy, batch experiments, X-ray photoelectron studies and energy dispersive spectroscopic studies. In addition, the Tb-MOF/Tb-AG can be reused for uranium adsorption.

Novel biocompatible and sensitive visual sensor based on aggregation-induced emission for on-site detection of radioactive uranium in water and live cell imaging.

In consideration of the severe hazards of radioactive uranium pollution, the rapid assessment of uranium in field and in vivo are urgently needed. In this work a novel biocompatible and sensitive visual fluorescent sensor based on aggregation-induced emission (AIE) was designed for onsite detection of UO22+ in complex environmental samples, including wastewater from Uranium Plant, river water and living cell. The AIE-active sensor (named as TPA-SP) was prepared with a "bottom-up" strategy by introducing a trianiline group (TPA) with a single-bond rotatable helix structure into the salicylaldehyde Schiff-base molecule. The photophysical properties, cytotoxicity test, recognition mechanism and the analytical performance for the detection of UO22+ in actual water samples and cell imaging were systematically investigated. TPA-SP exhibited high sensitivity and selectivity toward UO22+ as well as outstanding anti-interference ability against large equivalent of different ions in a wide effective pH range. A good linear relationship in the UO22+ concentration range of 0.05-1 µM was obtained with a low limit of detection (LOD) of 39.4 nM (9.38 ppb) for uranium detection. The prepared visual sensor showed great potential for fast risk assessment of uranium pollution in environmental systems. In addition, our results also indicated that the TPA-SP exhibited very low cytotoxicity in cells and demonstrated great potential for uranium detection in vivo.

Paternal exposure to microcystin-LR induces fetal growth restriction partially through inhibiting cell proliferation and vascular development in placental labyrinth.

Microcystin-leucine arginine (MC-LR) has reproductive and developmental toxicities. Previous studies indicated that gestational exposure to MC-LR induced fetal growth restriction in mice. The aim of this study was to further evaluate the effect of paternal MC-LR exposure before mating on fetal development. Male mice were intraperitoneally injected with either normal saline or MC-LR (10 µg/kg) daily for 35 days. Male mouse was then mated with female mice with 1:1 ratio. There was no significant difference on the rates of mating and pregnancy between MC-LR-exposed male mice and controls. Body weight and crown-rump length were reduced in fetuses whose fathers were exposed to MC-LR. Despite no difference on relative thickness of labyrinthine layer, cell proliferation, as measured by Ki67 immunostaining, was reduced in labyrinth layer of MC-LR-exposed mice. Moreover, blood sinusoid area in labyrinth layer was decreased in the fetus whose father was exposed to MC-LR before mating. Correspondingly, cross-sectional area of CD34-positive blood vessel in labyrinth layer was lower in fetuses whose fathers were exposed to MC-LR than in controls. These results provide evidence that paternal MC-LR exposure before mating induces fetal growth restriction partially through inhibiting cell proliferation and vascular development in labyrinth layer.

Microcystin-LR inhibits testosterone synthesis via reactive oxygen species-mediated GCN2/eIF2α pathway in mouse testes.

Previous studies demonstrated that microcystin-leucine-arginine (MC-LR) disrupted testosterone (T) synthesis, but the underlying mechanisms are not entirely elucidated. This study aims to explore the role of reactive oxygen species (ROS)-mediated GCN2/eIF2α activation on MC-LR-induced disruption of testicular T synthesis. Male mice were intraperitoneally injected with MC-LR (0 or 20 µg/kg) daily for 5 weeks. Serum T was decreased in MC-LR-exposed mice (0.626 ± 0.122 vs 24.565 ± 8.486 ng/ml, P < 0.01), so did testicular T (0.667 ± 0.15 vs 8.317 ± 1.387 ng/mg protein, P < 0.01). Steroidogenic proteins including StAR, CYP11A1 and CYP17A1 were downregulated in MC-LR-exposed mouse testes and TM3 cells. Mechanistically, p-GCN2 and p-eIF2α were elevated in MC-LR-exposed TM3 cells. GCN2iB attenuated MC-LR-induced GCN2 and eIF2α phosphorylation in TM3 cells. Moreover, GCN2iB attenuated MC-LR-induced downregulation of steroidogenic proteins in TM3 cells. Further analysis found that cellular ROS were elevated and HO-1 was upregulated in MC-LR-exposed TM3 cells. PBN rescued MC-LR-induced activation of GCN2/eIF2α signaling in TM3 cells. Additionally, pretreatment with PBN attenuated MC-LR induced downregulation of steroidogenic proteins and synthases in TM3 cells. These results suggest that ROS-mediated GCN2/eIF2α activation contributes partially to MC-LR-caused downregulation of steroidogenic proteins and synthases. The present study provides a new clue for understanding the mechanism of MC-LR-induced endocrine disruption.

Reactive oxygen species-evoked genotoxic stress mediates arsenic-induced suppression of male germ cell proliferation and decline in sperm quality.

This study aimed to investigate whether genotoxic stress mediates arsenic (As)-induced decline in sperm quality. Mice drank ultrapure water containing NaAsO2 (15 mg/L) for 70 days. The mature seminiferous tubules and epididymal sperm count were reduced in As-exposed mice. Cell proliferation, determined by immunostaining with Ki67, was suppressed in As-exposed seminiferous tubules and GC-1 cells. PCNA, a proliferation marker, was reduced in As-exposed mouse testes. Cell growth index was decreased in As-exposed GC-1 cells. Flow analysis showed that As-exposed GC-1 cells were retarded at G2/M phase. CDK1 and cyclin B1 were reduced in As-exposed GC-1 cells and mouse testes. Additional experiment revealed that p-ATR, a marker of genotoxic stress, was elevated in As-exposed mouse testes and GC-1 cells. Accordingly, p-p53 and p21, two downstream molecules of ATR, were increased in As-exposed GC-1 cells. Excess reactive oxygen species (ROS), measured by immunofluorescence, and DNA-strand break, determined by Comet assay, were observed in As-exposed GC-1 cells. γH2AX, a marker of DNA-strand break, was elevated in As-exposed seminiferous tubules and GC-1 cells. NAC alleviated As-evoked DNA damage, genotoxic stress, cell proliferation inhibition and sperm count reduction. In conclusion, ROS-evoked genotoxic stress mediates As-induced germ cell proliferation inhibition and decline in sperm quality.