Arabian Journal of Chemistry最新文献

The pervasive presence of mercury in water and cosmetics poses significant health risks, necessitating the development of a method for the in-situ monitoring and extraction of mercury ions. This study introduces a novel approach utilizing Mesoporous Silica Nanotubes (MSNTs) with a unique worm-like structure, providing an expansive surface area ideal for the adsorption of a Hg²⁺ ion chromophore, N,N,N,N′-Tetramethyl-4,4′-diaminobenzophenone. This configuration enables rapid and visible detection of toxic mercury, with a color transition from yellow to green that is easily discernible by the naked eye. The sensitivity of the Mercury nano-sensor (MNS) is remarkably high, with a detection limit of 1.9 × 10^-8 M as determined by digital image analysis, and 4.9 × 10^-8 M via spectrophotometric methods—both well below the WHO guidelines for drinking water. The MNS’s low detection threshold, coupled with its reusability after simple regeneration, positions it as an effective tool for preliminary water testing. The findings suggest that the MNS, requiring only 10 mg for measurements, offers a promising solution for the real-time visualization of mercury ions, enhancing safety measures in water and cosmetic products.

To prevent and control the methane/coal dust compound explosion disaster, the APP-diatomite composite powder inhibition of methane/coal dust compound explosion experiments were carried out in the self-constructed pipe network. The composite powder was characterized by scanning electron microscopy and X-ray photoelectron spectroscopy. The change rules of methane/coal dust composite explosion pressure and flame propagation velocity were analyzed using different compounding ratios of powders in several monitoring points. The results show that the composite powder exhibited irregular morphology and the APP powder is uniformly distributed on the diatomite porous mesh structure. When the APP loading on the surface of diatomite is 40 wt%, composite powder has the best effect on explosion suppression, with the peak maximum explosion overpressure and the peak maximum flame propagation velocity reduced by 71.5 % and 92.2 %, respectively. The explosion suppression mechanism is revealed through pyrolysis properties, explosion products, and chain reaction.

This study evaluates the application of supercritical carbon dioxide chelation extraction technology for treating heavy metal ions (Zn²⁺ and Cr³⁺) in drilling fluid waste. Through a combination of experimental and molecular dynamics simulation methods, the influence of extraction parameters (temperature, pressure, duration, and chelating agents) on the extraction efficiency are investigated. Findings show that increased duration and pressure significantly improve extraction efficiency, while temperature has a complex effect, initially increasing efficiency but plateauing and slightly decreasing at higher temperatures. The optimum extraction condition with pressure of 220 bar, temperature 348.15 K and an extraction duration of 70 min using ethylene diamine tetraacetic acid (EDTA) as the chelating agent has been determined. Importantly, molecular simulation analysis revealed that citric acid outperforms EDTA in terms of Zn²⁺ and Cr³⁺ aggregation by forming larger aggregates with greater numbers of molecules while reducing overall aggregate count. Furthermore, optimization of extraction pressure in the EDTA system shows potential benefits. These results suggest that supercritical carbon dioxide chelation extraction technology has strong potential for environmentally friendly and reliable waste management in the drilling industry. This study represents a significant step forward in developing sustainable solutions for heavy metal removal from drilling fluid waste.

Protein fibrillation is a crucial process in the onset of several neurodegenerative and retinal disorders due to the formation of cytotoxic species. Because of their capacity to prevent protein aggregation, small molecules have the potential to be appointed as therapeutic agents. Here, we examined the inhibitory impacts of the piperonal as a carbaldehyde-derived compound on the fibrillation process of α-synuclein and underlying cytotoxicity against neuron-like (PC12) and human retinal pigment epithelial (RPE) (ARPE-19) cells. The results showed that the values of k_app and lag time of α-synuclein were modulated with piperonal. Moreover, ANS fluorescence intensity analysis indicated that piperonal can inhibit the formation of a molten global (misfolded) state of α-synuclein, which is a necessary step in the formation of protein amyloid fibrils. Congo red absorption and circular dichroism spectroscopy also verified the inhibition of β-sheet structure formation after treatment of α-synuclein with piperonal. Furthermore, theoretical studies displayed that piperonal interacts with VAL40:HN, GLU35:O, VAL40, and LYS43 amino acid residues and forms a complex. In addition, cytotoxicity assays demonstrated that piperonal as a safe small molecule could mitigate the induced cytotoxicity by α-synuclein amyloids in PC12 and ARPE-19 cells through reduction of ROS and Bax/Bcl2 mRNA overexpression. Taken together, these outcomes showed that piperonal as a natural aldehyde compound can inhibit α-synuclein fibrillation and underlying cytotoxicity which may be developed for potential therapeutic applications in vivo.

This work presents an advanced automated monolithic C18 pipette-tip solid-phase extraction (PT-SPE) method seamlessly integrated with liquid chromatography-tandem mass spectrometry (LC-MS/MS) for precise therapeutic drug monitoring of eleven tyrosine kinase inhibitors (TKIs) in biological samples. Commercially available MonoTip C18 columns facilitate superior extraction efficiency and selectivity from complex biological matrices owing to their large surface areas and enhanced mass transfer capabilities. The sample preparation process, conducted by aspirating and dispensing solutions using a pipettor, completes the overall extraction process within 3 min. The method validation demonstrated excellent linearity within the range of 0.2/0.5/0.8 to 200 ng/mL, with detection limits ranging from 0.049 to 0.206 ng/mL. The method exhibited outstanding accuracy and precision, with intraday relative recovery rates ranging from 96.3 % to 115.0 % and interday recovery rates ranging from 95.0 % to 115.7 %, with coefficient of variation values consistently below 13.8 %. The proposed method is distinguished by its exceptional efficiency, reduced solvent use, enhanced environmental sustainability, and streamlined automation—key advantages in the realm of clinical therapeutic drug monitoring of TKIs. Overall, the MonoTip C18 PT-SPE technique, coupled with LC-MS/MS, offers a formidable, eco-friendly, and effective strategy for the TDM of TKIs, marking a significant advancement in the field.

The utilization of renewable solar energy for the photocatalytic transformation of carbon dioxide (CO₂) into valuable chemical substances is considered an optimal strategy to simultaneously address climate challenges and tackle energy scarcity. Herein, we prepared heterojunction photocatalysts UiO-66-NH₂/ZnIn₂S₄, which were successfully applied in the photocatalytic reduction of CO₂. The yield of the main product CO, for the optimal UiO-66-NH₂/ZnIn₂S₄-2 sample could reach up to 57 μmol g⁻¹h⁻¹ when converting CO₂ under the visible light irradiation, which was approximately 3.35 and 2.71 times higher than that achieved by the individual UiO-66-NH₂ and ZnIn₂S₄ samples, respectively. The better photocatalytic performance of the UiO-66-NH₂/ZnIn₂S₄-2 composites can be attributed to its synergistic effect resulting from tight interfacial contacts, special charge transfer pathways and excellent CO₂ adsorption capacity. Furthermore, the intimate contact between UiO-66-NH₂ and flower-like ZnIn₂S₄ accelerates electron transmission while effectively suppressing the quenching of photogenerated carriers. This research provides vital knowledge for the rational design of heterostructures aimed at enhancing the efficiency of CO₂ photocatalysis for solar fuel production.

A novel bio-covalent organic framework (COF: TpPa-SO₃H/Lignin) based on TpPa-SO₃H and lignin from lignocellulose was synthesized for chromium (Cr(VI)) remediation in this study. Results showed that TpPa-SO₃H/Lignin had a highest adsorption capacity at the range of 5 ∼ 75 mg/L Cr(VI) under 10 mg/L dosage, in which 100 % Cr(VI) could be removal within 120 min. Likewise, the introduction of lignin improved the visible light response range, charge separation and photogenerated carriers, thereby improving the photocatalytic efficiency of Cr(VI) by TpPa-SO₃H/Lignin. The highest photocatalytic efficiency of TpPa-SO₃H/Lignin (98.56 %) was observed at the acidic conditions. ESR result shows that e- and ·O₂^– are generated and played an important role during the photocatalytic reaction, while the contribution of ·OH to Cr(VI) photoreduction is negligible. This study presents a sustainable and efficient approach to mitigating Cr(VI) pollution. It opens up avenues for further exploration of lignocellulose-derived materials in environmental applications and highlights the potential of COFs in addressing heavy metal contaminants.

Uncontrolled activation of c-Kit is closely related to the pathogenesis and progression of leukemia, gastrointestinal cancer, and other malignant diseases. Although there are several inhibitors available, due to the limitation of selectivity and the unfavorable side effects, designing and discovering highly selective inhibitors targeting c-Kit kinase, especially the gain of function mutation (for example c-Kit D816V), is still necessary. To identify novel c-Kit inhibitors, a metastable state-based virtual screening approach, which was successfully implemented in other kinase inhibitors, was employed in the current study. The results from our current study demonstrated the residues adjacent to the DFG motif within the activation loop could fold into short α-helices aside from the random coil, which was commonly found in the crystal structure. By expanding the conformation pool of the activation loop via PyRosetta-based ab initio folding protocol, we constructed a series of structural models of the c-Kit kinase intermediate between the inactive and active states. After evaluation of the thermal stability of the metastable state with molecular dynamics simulation, one structural model showed higher stability of α-helix, and the activation loop was retained. Considering the wild-type and D816V mutated KIT kinase shared similar metastable states during the kinase activation process, we developed a hypothesis that the identified intermediate might hold the potential to identify inhibitors targeting D816V mutations from the compound database. As expected, the intermediate structure showed higher selectivity to KIT D816V selective inhibitors, such as bezuclastinib, avapritinib, BLU-263, and elenestinib, than imatinib or masitinib. The virtual screening of the available KIT kinase inhibitor database further identified vorolanib, semaxanib, henatinib, and pexmetinib may possess potential inhibitory effects against wild type, as well as the mutated c-Kit kinase. The results from our current study not only proposed a novel structural model that could be used for the identification of selective c-Kit D816V inhibitors but also identified several potential inhibitors from available kinase inhibitors, which might shed new light on the design of new therapeutic approaches for c-Kit mutation-driven malignant diseases.

Utilizing synthetic insecticides to control mosquito populations has many adverse side effects as they can cause environmental pollution and insecticide resistance. Therefore, the search for eco-friendly and effective mosquito control agents has led to the exploration of plant extracts with larvicidal efficacy. In this study, we aimed to explore the larvicidal activity of four Egyptian plant extracts: Rosmarinus officinalis, Melissa officinalis, Cichorium intybus, and Beta vulgaris var. cicla against Culex pipiens and to identify the chemical constituents present in the active extracts. The methanolic extracts of the four plants were prepared and tested against the third instar larvae of C. pipiens using a standard method. The lethal concentrations (LC₅₀ and LC₉₀) were calculated using probit analysis. The active extracts were subjected to ultra-performance liquid chromatography-mass spectroscopy (UPLC-MS/MS) analysis and the data were processed using the global natural products social molecular networking (GNPS) platform to generate molecular networks and identify the compounds based on spectral similarity and database matching. The methanolic extracts of R. officinalis L. and M. officinalis L. had the highest larvicidal activity, where LC₅₀ values were 9.795 and 26.505 μg/mL, respectively. Their exposure caused a high mortality rate and disrupted the biochemical and physiological parameters (total carbohydrates, total lipids, total protein, acetylcholinesterase (AChE), and glutathione S-transferase (GST) in the body of C. pipiens when compared with Cichorium intybus (Chicory) and Beta vulgaris var. cicla (Chard). The UPLC-MS/MS analysis with the aid of the GNPS platform, revealed the presence of 23 and 41 metabolites from R. officinalis L. and M. officinalis L., respectively. The identified metabolites may act as larvicidal agents by interfering with the physiological or biochemical processes of the mosquito larvae. Overall, the findings suggest that the methanolic extracts of R. officinalis and M. officinalis are potential sources of natural larvicides for mosquito control.

In this research work, we designed a smart biodegradable PEG-coated MnO₂ nanoparticles conjugated with doxorubicin (PMnO₂-Dox NPs) for dual chemo-photodynamic therapy and magnetic resonance imaging (MRI) application. This highly sensitive pH-responsive PMnO₂-Dox NPs causes effective drug release under acidic pH environment. PMnO₂-Dox NPs not only improves the efficacy of chemo-photodynamic therapy due to synergistic response as well as improved MRI imaging via boosting T₁ MRI contrast. Manifold characterization techniques have been employed for materials investigation. Crystallography of PMnO₂-Dox NPs were performed by using XRD analysis, which confirmed tetragonal crystal structure with an approximate crystallite size of 20–30 nm. Surface morphology was confirmed via SEM analysis, results indicated the spherical and asymmetric agglomerated nanocluster of PMnO₂-Dox NPs. In in vitro bioassay, the anticancer activity of PMnO₂-Dox NPs were tested against breast cancer (MCF-7) cell line using MTT test. Moreover, it can also inhibit the growth of primary and secondary cancers without light exposure. Results suggested that PMnO₂-Dox NPs not only convenient for cancer treatment via combined chemo-photodynamic therapy but also address the way towards a comprehensive strategy for MRI application via bright contrast agent T1 after overcoming the problem of multidrug resistance (MDR) and synergistic response of therapeutic analysis.