Sulphur dioxide and fluoride co-exposure cause enamel damage by disrupting the Cl-/HCO3- ion transport.

OBJECTIVE: Although there is growing evidence linking the exposure to sulphur dioxide (SO2) and fluoride to human diseases, there is little data on the co-exposure of SO2 and fluoride. Moreover, literature on SO2 and fluoride co-exposure to enamel damage is insufficient. In this work, we concentrate on the concurrent environmental issues of excessive SO2 and fluoride in several coal-consuming regions. METHOD: To identify the toxicity of SO2 and fluoride exposure either separately or together, we used both ICR mice and LS8 cells, and factorial design was employed to assess the type of potential combined action. RESULT: In this study, co-exposure to SO2 and fluoride exacerbated enamel damage, resulting in more severe enamel defects of incisor and the damage occurred earlier. Cl-/HCO3- exchanger expression is increased by SO2 and fluoride in mouse incisor. Consistent with in vivo results, co-exposure of SO2 and fluoride decreased pHi and increased [Cl-]i level by increasing the expression of the Cl-/HCO3- exchanger in LS8 cells. Furthermore, SO2 and F may increase merlin protein expression, and merlin deficiency causes AE2 expression to decrease in vitro. CONCLUSION: Overall, these results indicate that co-exposure to SO2 and fluoride may result in more toxicity both in vitro and in vivo than a single exposure to SO2 and fluoride, suggesting that residents in areas contaminated with SO2 and fluoride may be more likely to suffer enamel damage.

Sodium Fluoride and Sulfur Dioxide Derivatives Induce TGF-ß1-Mediated NBCe1 Downregulation Causing Acid-Base Disorder of LS8 Cells.

The aim of the present work was to assess whether the combination of sodium fluoride (NaF) and sulfur dioxide derivatives (SO2 derivatives) affects the expression of the electrogenic sodium bicarbonate cotransporter NBCe1 (SLC4A4), triggering an acid-base imbalance during enamel development, leading to enamel damage. LS8 cells was taken as the research objects and fluorescent probes, quantitative real-time polymerase chain reaction (qRT-PCR), western blot, and factorial analysis were used to clarify the nature of the fluoro-sulfur interaction and the potential signaling pathway involved in the regulation of NBCe1. The results showed that exposure to fluoride or SO2 derivatives resulted in an acid-base imbalance, and these changes were accompanied by inhibited expression of NBCe1 and TGF-ß1; these effects were more significant after fluoride exposure as compared to exposure to SO2 derivatives. Interestingly, in most cases, the toxic effects during combined exposure were significantly reduced compared to the effects observed with fluoride or sulfur dioxide derivatives alone. The results also indicated that activation of TGF-ß1 signaling significantly upregulated the expression of NBCe1, and this effect was suppressed after the Smad, ERK, and JNK signals were blocked. Furthermore, fluoride and SO2 derivative-dependent NBCe1 regulation was found to require TGF-ß1. In conclusion, this study indicates that the combined effect of fluorine and sulfur on LS8 cells is mainly antagonistic. TGF-ß1 may regulate NBCe1 and may participate in the occurrence of dental fluorosis through the classic TGF-ß1/Smad pathway and the unconventional ERK and JNK pathways.

Electrochemical and Photoelectrochemical Detection of Hydrogen Peroxide Using Cu2O/Cu Nanowires Decorated with TiO2-x Deriving from MXenes.

H2O2 is a major transmitter of redox signals in electrochemical processes, whose detection is relevant for various industries. Herein, we developed a new fabrication method for a Cu2O/Cu nanowire-based nonenzymatic H2O2 electrochemical sensor that was decorated with irregular TiO2-x nanoparticles deriving form Ti3C2 MXene. The TiO2-x/Cu2O/Cu-NW electrodes possess excellent selectivity, stability, and reproducibility for H2O2 detection in both EC and PEC operational modes. In the EC detection of H2O2, the TiO2-x/Cu2O/Cu-NW electrode shows a linear relationship in the range from 10 µM to 42.19 mM and a low detection limit of 0.79 µM (S/N = 3), which has a similar sensitivity but a much broader linear range compared with the commercial H2O2 analyzer (0-5.88 mM, Q45H/84, US-QContums). It also shows excellent recovery in detecting H2O2 in the real orange juice and milk samples with the recovery ranging from 96.9 to 105%, indicating the potential for practical applications. In the PEC detection of H2O2, the TiO2-x/Cu2O/Cu-NW electrode shows a lower detection limit of 59 nM (S/N = 3), which is 13 times more sensitive than the EC electrode. The enhanced PEC performance can be attributed to the formation of p-n heterojunction between TiO2-x and Cu2O, which improves light utilization and inhibits the recombination of photo-induced electrons and holes. This work illuminates the extraordinary potential of MXene-derived TiO2 in electrochemical and photoelectrochemical applications.

Selective reduction of nitrate into N2 by novel Z-scheme NH2-MIL-101(Fe)/BiVO4 heterojunction with enhanced photocatalytic activity.

Nitrate and its metabolites as common pollutants in water had attracted widespread attentions. Converting nitrate to nontoxic and harmless nitrogen via photocatalysis was a promising approach. In this study, a novel Z-scheme NH2-MIL-101(Fe)/BiVO4 heterojunction was successfully prepared. As-prepared Z-scheme heterojunction along with built-in electric field facilitated the charge separation and enhanced the photocatalytic activity in nitrate reduction. The results showed that 0.10-MBiVO photocatalyst exhibited the highest nitrate removal rate of 94.8% (initial concentration 100 mgN/L) and final selectivity to N2 of 93.4% in 50 min under ultraviolet irradiation. Moreover, formic acid was proved as better hole scavenger compared with methanol and oxalic acid. And the concentration of formic acid had significant influence on the process of nitrate photocatalytic reduction. 0.10-MBiVO photocatalyst exhibited excellent reusability in the recycling tests, indicating its great potential in practical application of nitrate photocatalytic removal. The mechanism of the enhancement as well as reaction pathways for nitrate photocatalytic reduction on NH2-MIL-101(Fe)/BiVO4 were comprehensively explored and described at the end.

Three-dimensionally ordered macro-mesoporous CoMo bulk catalysts with superior performance in hydrodesulfurization of thiophene.

The introduction of surfactants during the fabrication of hydrodesulfurization catalysts could not only tune the microstructure but also promote the dispersion of active components. In this work, CoMo bulk catalysts with the hierarchical structure of three-dimensionally ordered macro-mesopores were successfully fabricated by using a colloidal crystal template with the addition of PEG 400 and/or F127 surfactants. The obtained samples were characterized by various techniques, and the possible mechanism of the structure formation was also discussed. The characterization and evaluation results reveal that the addition of surfactants can promote the formation of the mesopores (3-4 nm) inside the macroporous walls of these bulk catalysts, which is essential for the increase of catalyst surface area, and the active sites for reaction. The CoMo-PF-1 catalyst displayed superior catalytic performance for thiophene hydrodesulfurization with the thiophene conversion of 99.4% under 1 MPa at 360 °C, which is much higher than that (77.8%) at 0.1 MPa. This result is even comparable to our previous report with the thiophene conversion of 99.2% over the 3DOM CoMo catalyst under 3 MPa.

Carbon dots functionalized by organosilane with double-sided anchoring for nanomolar Hg2+ detection.

Surface functional groups on carbon dots (CDs) play a critical role in defining their photoluminescence properties and functionalities. A new kind of organosilane-functionalized CDs (OS-CDs) were formed by a low temperature (150°C) solvothermal synthesis of citric acid in N-(ß-aminoethyl)-γ-aminopropylmethyl-dimethoxysilane (AEAPMS). Uniquely, the as-synthesized OS-CDs have dual long chain functional groups with both NH2 and Si(OCH3)3 as terminal moieties. Double sided anchoring of AEAPMS on CDs occurs, facilitated by the water produced (and confined at the interface between CDs and solvent) when citric acid condenses into the carbon core. The resultant OS-CDs are multi-solvent dispersible, and more significantly, they exhibit excellent selectivity and sensitivity to Hg(2+) with a linear detection range of 0-50 nM and detection limit of 1.35 nM. The sensitivity and selectivity to Hg(2+) is preserved in highly complex fluids with a detection limit of 1.7 nM in spiked 1 M NaCl solution and a detection limit of 50 nM in municipal wastewater effluent. The results show that the OS-CDs synthesised by the solvothermal method in AEAPMS may be used as an effective Hg(2+) sensor in practical situations.

Graphene oxide membranes with tunable permeability due to embedded carbon dots.

In this communication, we fabricated graphene oxide membranes with tunable permeation by embedding carbon nanodots of controllable sizes.

Hierarchical branched Cu2O nanowires with enhanced photocatalytic activity and stability for H2 production.

Hierarchical branched Cu2O nanowires were synthesized under mild conditions and exhibit remarkable performance for photocatalytic H2 generation from water. The obtained results open appealing perspectives for converting solar energy into storable chemical energy.