Bisphenol A and bisphenol AF co-exposure induces apoptosis in human granulosa cell line KGN through intracellular stress-dependent mechanisms

Bisphenol A (BPA) is a chemical substance used in large amounts in the production of epoxy resins, phenolic resins and polycarbonate plastics. Although its toxicity to the female reproductive system has been extensively studied, little is known about the combined toxicity of BPA and its analogues. In this study, the human granulosa cell line KGN was co-exposed to BPA and bisphenol AF (BPAF), and we subsequently examined the effect of these chemicals on cell apoptosis and their mechanism. We found that co-exposure to BPA and BPAF induced intracellular stress in KGN cells, including significantly elevated levels of reactive oxygen species (ROS) and calcium ions (Ca²⁺). Then, apoptosis and its associated biological events, including increased caspase-3 activity, and decreased Bcl-2/Bax protein expression ratio, were measured under the combined exposure. Notably, we confirmed that the intracellular stress and activation of the signaling axis of the downstream ASK1-JNK signaling pathway involved in the apoptosis of KGN cells was induced by the mixture of BPA and BPAF. In addition, we verified with pretreatment inhibitors that the BPA and BPAF mixture promoted the co-induction of KGN cell apoptosis via this stress pathway. Our work provides novel insights into the combined cytotoxicity and molecular toxicity mechanism of bisphenol mixtures.     

The effects of hydrogen peroxide on the sonochemical degradation of phenol and bisphenol A

This report describes the effects of H₂O₂ concentration (0.01, 0.1, 1, and 10 mM) on the sonochemical degradation of phenol and bisphenol A (BPA) using an ultrasonic source of 35 kHz and 0.08 W/mL. The concentration of the target pollutants (phenol or BPA), total organic carbon (TOC), and H₂O₂ were monitored for each input concentration of H₂O₂. The effects of H₂O₂ on the sonochemical degradation of phenol was more significant than that of BPA because phenol has a high solubility and low octanol–water partition coefficient (K_ow) value and is subsequently very likely to remain in the aqueous phase, giving it a greater probability of reacting with H₂O₂. The removal of TOC was also enhanced by the addition of H₂O₂. Some intermediates of BPA have a high K_ow value and subsequently have a greater probability of pyrolyzing by the high temperatures and pressures inside of cavitation bubbles. Thus the removal efficiency of TOC in BPA was higher than that of phenol. The removal efficiencies of TOC were lower than the degradation efficiencies of phenol and BPA. This result is due to the fact that some intermediates cannot readily degrade during the sonochemical reaction. The H₂O₂ concentration decreased but was not completely consumed during the sonochemical degradation of pollutants. The initial H₂O₂ concentration and the physical/chemical characteristics of pollutants were considered to be important factors in determining the formation rate of the H₂O₂. When high concentration of H₂O₂ was added to the solution, the formation rates were relatively low compared to when low concentrations of H₂O₂ were used.     

On-line solid phase extraction fast liquid chromatography–tandem mass spectrometry for the analysis of bisphenol A and its chlorinated derivatives in water samples

In this study an on-line column-switching fast LC–MS/MS method was developed to analyze bisphenol A (BPA) and its chlorinated derivatives in water. Fast liquid chromatographic separation was performed on a C18 reversed phase column based on fused-core particle technology (2.7 μm particle size) providing analysis times shorter than 3 min and high peak efficiencies. The main benefit of this LC system is that it can easily be hyphenated to a conventional on-line preconcentration device allowing the direct analysis of water samples without any pretreatment at concentrations levels down to 60 ng L⁻¹ and preventing contaminations frequently reported in the analysis of BPA. This on-line SPE fast LC system was coupled to a triple quadrupole mass spectrometer operating in enhanced mass resolution mode (Q1 FWHM = 0.7 Th, Q3 FWHM = 0.1 Th) in order to minimize interferences and chemical noise. This highly sensitive and selective method was successfully employed to analyze BPA and its chlorinated derivatives in water samples.     

Effect of asymmetrical flow field-flow fractionation channel geometry on separation efficiency

The separation efficiencies of three different asymmetrical flow field-flow fractionation (AF4) channel designs were evaluated using polystyrene latex standards. Channel breadth was held constant for one channel (rectangular profile), and was reduced either linearly (trapezoidal profile) or exponentially (exponential profile) along the length for the other two. The effective void volumes of the three channel types were designed to be equivalent. Theoretically, under certain flow conditions, the mean channel flow velocity of the exponential channel could be arranged to remain constant along the channel length, thereby improving separation in AF4. Particle separation obtained with the exponential channel was compared with particle separation obtained with the trapezoidal and rectangular channels. We demonstrated that at a certain flow rate condition (outflow/inflow rate = 0.2), the exponential channel design indeed provided better performance with respect to the separation of polystyrene nanoparticles in terms of reducing band broadening. While the trapezoidal channel exhibited a little poorer performance than the exponential, the strongly decreasing mean flow velocity in the rectangular channel resulted in serious band broadening, a delay in retention time, and even failure of larger particles to elute.     

Sunlight assisted photocatalytic degradation of organic pollutants using g-C3N4-TiO2 nanocomposites

The photocatalytic degradation of environmentally non-benign, toxic organic pollutants such as bisphenol A (BPA), brilliant green (BG), or mixture of dyes have been carried out using g-C₃N₄-TiO₂ (GNT) nanocomposites. The GNT nanocomposites were synthesized by using hydrothermal method with different compositions and these nanocomposites were characterized using the different techniques. X-ray diffraction revealed that the anatase phase of TiO₂ has been retained in composites; while characteristic reflection of g-C₃N₄ at 27.07° (d = 3.22 Å) is not observed due to its lower content in the nanocomposites. Raman spectra confirms the formation of composites between TiO₂ with g-C₃N₄. Furthermore nano-scale dimensions of the bare or composites have been proved by FE-SEM and HR-TEM analysis. X-ray photoelectron spectroscopy (XPS) shows the presence of C, N, Ti and O as a constituents, with peaks due to CC, NCN of g-C₃N₄. Among the different nanocomposites, g-C₃N₄-TiO₂ catalyst having 30% g-C₃N₄ and 70% TiO₂ in molar proportion (i.e. 30-GNT) is exhibiting the highest efficiency for degradation of the different dyes in correlation to its higher surface area, lower optical band gap as well as more visible-light absorption (i.e., λ > 400 nm) in the electromagnetic spectrum.     

Photodegradation of bisphenol A polycarbonate with different types of stabilizers

When unstabilized bisphenol A polycarbonate is exposed to outdoor weathering conditions, it degrades due to irradiation, humidity and other parameters. To overcome this undesired degradation process BPA-PC can be stabilized. In this study the influence of different types of stabilizers (i.e. UV-absorbers and hindered amine stabilizers) on the photodegradation of BPA-PC were compared. It is shown that the best way to stabilize BPA-PC is to keep the harmful UV light out. Almost all stabilizers caused a decreased degradation rate. The UVAs showed the best results, although radical scavengers cause a decrease in degradation too. By applying a layer of UVA-stabilized BPA-PC on top of unstabilized BPA-PC led to a decreased degradation rate of the unstabilized BPA-PC, which can quantitatively be explained by a reduction of the irradiation intensity.     

Photodegradation of bisphenol A polycarbonate

When bisphenol A polycarbonate is subjected to weathering conditions this polymer shows two different degradation mechanisms depending on the used irradiation wavelengths, i.e. photo-oxidation and photo-Fries rearrangement. The relative importance of these mechanisms in outdoor exposure conditions is still unknown. In this study bisphenol A polycarbonate is exposed to simulated weathering conditions. Different analysing techniques show that photo-oxidation is the most dominant degradation reaction. However, fluorescence spectroscopy shows that small amounts of photo-Fries rearrangement products are formed. With model compounds blended in polypropylene it is shown that the photo-Fries reaction increases the photo-oxidation rate, thus in PP the photo-Fries reaction can proceed through radical intermediates. However, this is not the case in PC, ageing at condition causing an increased photo-Fries reaction rate did not result in a higher oxidation rate. This implies that in PC the photo-Fries reaction does not initiate its oxidation and thus does not proceed through radicals.     

The Rohlin property for shifts of finite type

We show that an automorphism of a unital AF C^*-algebra with a certain approximate Rohlin property has the Rohlin property. This generalizes a result of Kishimoto. Using this we show that the shift automorphism on the bilateral C^*-algebra associated with an aperiodic irreducible shift of finite type has the Rohlin property.     

Electrochemical impedance spectroscopy of diluted solutions of Bisphenol A

The electrochemical oxidation of bisphenol A was carried out using platinum, glassy carbon, titanium dioxide and polypyrrole modified working electrodes. Acetonitrile and water were evaluated as solvents; however, passivation could not be avoided due to the formation of insoluble oxidation products that adhere to the surface. The use of ultrasound did not show any improvement either. Finally, by using electrochemical impedance spectroscopy measurements at the open circuit potential it was possible to obtain a steady response of one of the components of the equivalent circuit proposed. This response is only dependent on the concentration of bisphenol A. At the same time it was demonstrated that the adsorption is a fundamental process that occurs more easily in water than in acetonitrile, this fact is reflected in the impedance spectra.     

“Orange alert”: A fluorescent detector for bisphenol A in water environments

Due to the prevalent use of polycarbonate plastics and epoxy resins in packaging materials and paints for ships, there has been a widespread global contamination of environmental water sources with bisphenol A (BPA). BPA, an endocrine disruptor, has been found to cause tremendous health problems. Therefore, there is an urgent need for detecting BPA in a convenient and sensitive manner to ensure water safety. Herein, we develop a fluorescent turn-on BPA probe, named Bisphenol Orange (BPO), which could conveniently detect BPA in a wide variety of real water samples including sea water, drain water and drinking water. BPO shows superior selectivity toward BPA and up to 70-fold increase in fluorescence emission at 580 nm when mixed with BPA in water. Mechanistic studies suggest a plausible water-dependent formation of hydrophobic BPA clusters which favorably trap and restrict the rotation of BPO and recover its inherent fluorescence.