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A sensor based on graphite nanosheets was fabricated through the electrochemical expansion of a graphite electrode in dimethyl sulfoxide for the sensitive electrochemical determination of enrofloxacin. The modified electrode surface exhibited a distinctive structure of nanoplates, characterized by layer thickness ranging from a few nanometers to ten nanometers. The developed electrode displayed notable electrochemical properties, including a faster charge transfer rate and a larger electrochemically active surface area, which was 1.3 times greater compared to the unmodified electrode. As a result, the sensor improved square wave voltammetric signals for enrofloxacin, exhibiting a 2.4-fold enhancement compared to the unmodified electrode. By optimizing the experimental parameters such as electrode fabrication conditions, pH of analytical solution, and adsorption time for enrofloxacin, the sensor demonstrated good reproducibility and a strong linear correlation over two ranges of enrofloxacin concentrations from 0.05–0.15 μM and 0.1–20 μM. The limit of detection was determined to be 0.002 μM. The sensor was successfully employed for the determination of enrofloxacin in spiked surface water samples before and after treating enrofloxacin by a photocatalytic method. The obtained results exhibited consistency with those obtained using a liquid chromatography-tandem mass spectrometry reference method, and a high recovery rate of 105.5% further confirmed the reliability of the proposed method for enrofloxacin detection. [ABSTRACT FROM AUTHOR]

Hierarchically bimetallic Zr-Cu metal–organic framework combined with 1,3,5-benzenetricarboxylic acid (Zr-CuBTC MOFs) was synthesized using hydrothermal reaction and used as modifier for investigation of non-electroactive glyphosate. These MOFs were dropcasted on a glassy carbon electrode (GCE) and non-electroactive glyphosate were tested by cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and differential pulse voltammetry (DPV). Glyphosate in water was recognized by the difference of currents in spiked and non-spiked glyphosate samples. At the same time, CuBTC and Fe-CuBTC were investigated for the best material for sensor development. The results showed the bimetallic Zr-CuBTC MOF is the most promising for the determination of glyphosate. Morphological and structural studies showed the coordination of Cu2+ with the presence of Zr4+ ions with BTC ligands provided a highly porous framework with active surface area up to 1337 m2 g−1. The pore diameter and pore volume increased to 1.75 nm and 0.687 cm3 g−1, respectively. Under optimal conditions, Zr-CuBTC modified on GCE (Zr-CuBTC/GCE) sensor is able to indirectly detect glyphosate in a water environment at a detection limit as low as 9 × 10−13 M. The developed sensor was employed to determine glyphosate in the surface water samples collected from the Red River, North Vietnam. The results showed good recoveries (94.6–107.1%) which were in agreement with liquid chromatography coupled tandem mass spectrometry (LC-MS/MS) measurements. These results demonstrate the possibility of using this MOF material in sensor applications to determine trace pesticides in the contaminated water. [ABSTRACT FROM AUTHOR]

Cancer is a global concern and the potential targeting of cancer stem cells (CSCs) has gained major attention in anticancer drug discovery research. Various natural compounds have shown promising effects in suppressing cancer, prompting scientific interest. In this study, we investigated the anti-CSC properties of schisandracaurin C, a novel compound derived from the Vietnamese plant Schisandra cauliflora. To evaluate its anti-CSC efficacy, we employed the MTT assay, flow cytometry analysis, the caspase-3 assay and a three-dimensional cell culture method, focusing on the teratocarcinoma NTERA-2 cells. Our findings revealed that schisandracaurin C inhibited the growth of NTERA-2 cells with an IC50 value of 16.61±0.13 μM, which was significantly lower than that on HEK-293A healthy embryonic kidney cells (22.72±0.02 μM) (P<0.05). Schisandracaurin C was toxic to NTERA-2 cells within three-dimensional tumorspheres (IC50: 33.47±1.45 μM). The anti-CSC effects of schisandracaurin C on NTERA-2 cells were mediated through apoptosis, as evidenced by increased caspase-3 activity. Schisandracaurin C induced cell cycle arrest at the S phase in NTERA-2 cells. These findings highlight the potential of schisandracaurin C as a promising anti-CSC compound, which warrants further mechanistic and clinical investigations. [ABSTRACT FROM AUTHOR]

Ciprofloxacin (Cip), a fluoroquinolone antibiotic, was determined by linear sweep adsorptive stripping voltammetric method using multilayer reduced graphene oxide electrode (m-rGO). The m-rGO electrode was fabricated directly, simply and promptly from graphite platform by potentiostatic technique without further modification. The produced electrode exhibited excellent performance for ciprofloxacin (Cip) determination with a much higher signal of Cip than that on the initial graphite electrode (13.4 times). This dominance of the m-rGO electrode resulted from the large electrochemically active surface area, electrochemical catalysis, suitable functional groups on the electrode surface. Experimental conditions such as the electrode fabrication time, the supporting solution, and accumulation time were optimised to obtain the Cip highest signal. A Cip analytical method established under the optimal conditions had a good linear relationship between the Cip signal with its concentration range from 0.5 to 20 µM (R2 = 0.9953). The method showed a low detection limit (LOD = 0.078 µM), satisfactory reproducibility (RSD = 1.50%), and high accuracy. Cip concentration in a spiked lake water sample determined by the proposed method with acceptable precision (RSD = 5.59%) and trueness (recovery = 94.2–106.3%) was comparable with LC-MS/MS method. [ABSTRACT FROM AUTHOR]

Vibrio spp. cause vibriosis in many saltwater and freshwater aquatic species, such as fish, crustaceans, and mollusks. Vibrio parahaemolyticus and Vibrio alginolyticus are among the few Vibrio species commonly found in infections in fish. This study aimed at investigating the chemical composition and evaluating the antibacterial activities of Salix babylonica L. The ethyl acetate (LL2) and methanolic (LL3) extracts were used to evaluate the resistance of strains as V. parahaemolyticus LBT6 and VTCC 12233, and two strains of V. alginolyticus, NG20 and ATCC 17749, and compared their efficacy with cefotaxime in order to find an alternative to antibiotics in the treatment of vibriosis. The obtained results show that the LL2 extract, with its major components identified as chrysoeriol, luteolin, and β-sitosterol, exhibited a bacteriostatic effect against all the tested strains. In parallel, the LL3 extract, with the four major compounds luteolin-7-O-β-D-glucopyranoside, salicin, p-hydroxy benzoic acid, and β-sitosterol-3-O-β-D-glucopyranoside, showed significant bactericidal activity against these four strains; the minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) varied from 2.0 to 3.0 μg/mL and from 3.5 to 5.0 μg/mL, respectively. Moreover, the LL3 extract could effectively increase the survival rate of the challenged fish at a dose of 5% (w/w) for the zebrafish (Danio rerio) and 3% (w/w) for the sea bass (Lates calcarifer). The LL3 extract showed a potential application of S. babylonica L. in the prevention and treatment of vibriosis in fish. [ABSTRACT FROM AUTHOR]

A new approach for fabricating high-performance electrochemical sensors for lead ion detection using the square-wave anodic stripping voltammetry method was developed. The sensor consisted of a working electrode fabricated from silver nanowires (AgNWs) and graphene oxide (GO) on polyethylene terephthalate substrates. The morphological, electrochemical properties and operational parameters of the electrode were investigated. Owing to the combination of the pressing method and overcoated GO layer, the electrode possessed good conductivity and high stability, suitable for the fabrication of electrochemical sensors for detecting Pb(II). Under the optimum experimental conditions, the calibration curve exhibited a good linear relationship over a wide range of Pb(II) concentrations (0.2–60 µg L−1), with a correlation coefficient of 0.9983. The detection limit of the sensor for Pb(II) is 0.067 µg L−1, which is significantly less than the safety limit for drinking water defined by the World Health Organization. The electrochemical sensor exhibited good repeatability and high stability after sixty days of storage. In addition, the prepared electrochemical sensor possesses low cost, simplicity, easy to use, and the large production ability. This study contributes to the application of AgNW/GO hybrid electrodes for Pb(II) detection. [ABSTRACT FROM AUTHOR]

A new compound, physalucoside A (1), together with seven withanolides (2–8) and three flavonoids (9–11), were isolated from Physalis angulata L. (Solanaceae), a medicinal plant native to Vietnam. The chemical structures of these compounds were elucidated by one- and two-dimensional NMR spectra, high-resolution electrospray ionization mass spectrometry analyses, and chemical reactivity. The anti-inflammatory and cytotoxic activities of isolated compounds were also evaluated. These data suggest that the anti-inflammatory activity of P. angulata is due primarily to its withanolide content. This study demonstrates the potential of withanolides as promising candidates for the development of new anti-inflammatory drugs. [ABSTRACT FROM AUTHOR]

A reduced graphite oxide nanosheet electrode (RGOnS) was prepared as a sensor for amoxicillin (AMX) detection, an antibiotic commonly used in the livestock farm, by the square-wave adsorptive stripping voltammetry technique. Graphite oxide with nanosheet shape was produced from a graphite electrode by a chronoamperometry process at 5 V and then an electrochemical reduction process was carried out to form RGOnS with restored long-range conjugated networks and better conductivity. The electrodes were characterized by SEM, EDX, and FTIR spectroscopy. The RGOnS electrode prepared at an optimal reduction potential of −1 V for 120 s exhibits a larger electrochemical active surface area, and the obtained oxidation signal of AMX is approximately ten times higher than that of the pristine graphite electrode. The analytical conditions such as the pH of electrolyte and accumulation time were optimized. The calibration curve built under the optimal conditions provided a good linear relationship in the range of AMX concentration from 0.5–80 µM with the correlation coefficient of 0.9992. The limit of detection was calculated as 0.193 µM. Satisfactory results are obtained from the detection of the AMX in different samples using the prepared electrode. [ABSTRACT FROM AUTHOR]

The present paper reports the fabrication of inverse opal photonic crystals (IOPCs) by using SiO2 spherical particles with a diameter of 300 nm as an opal photonic crystal template and poly(ethylene glycol) diacrylate (PEGDA) as an inverse opal material. Characteristics and fluorescence properties of the fabricated IOPCs were investigated by using the Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), X-ray diffraction (XRD), reflection spectroscopy, and fluorescence microscopy. The results clearly showed that the IOPCs were formed comprising of air spheres with a diameter of ∼270 nm. The decrease in size led to a decrease in the average refractive indexes from 1.40 to 1.12, and a remarkable stopband blue shift for the IOPCs was thus achieved. In addition, the obtained results also showed a fluorescence enhancement over 7.7-fold for the Fluor® 488 dye infiltrated onto the IOPCs sample in comparison with onto the control sample. [ABSTRACT FROM AUTHOR]

Despite the diverse roles of singlet oxygen (1O2) in plants and animals, simple detection of 1O2 has been limited due to technical difficulties. Here we report a colorimetric method for visualizing the generation and suppression of 1O2 using a protein photo-sensitizer, mini singlet oxygen generator (miniSOG). Upon external light irradiation, miniSOG strongly produced 1O2 and oxidized a universal chromogenic reagent, tetramethylbenzidine, leading to a rapid color change in solution. We used this finding to demonstrate the 1O2 scavenging effects of well-known anti-oxidants and of natural compounds extracted from plants. Owing to its high usability and simplicity, our developed assay platform will be useful for screening potential scavengers for reactive oxygen species and will promote the development of various antioxidants. [ABSTRACT FROM AUTHOR]

We introduce the fabrication and electrochemical application of platinum nanoflower-modified glassy carbon electrode (PtNFs/GCE) for the trace level determination of lead and cadmium using differential pulse anodic stripping voltammetry (DPASV). The modified electrodes have been characterized by EDX, XRD, SEM, and AFM techniques to confirm chemical and physical properties. The effect of potential electrodeposition on the properties of the electrode was investigated. At −0.2 V of potential, platinum developed with a nanoflower shape and dispersed densely all over the glassy carbon surface. In this condition, the highest of lead and cadmium electrochemical signals was clearly observed. The sensor showed wide linearity in the concentration range of 1–100 μg·L−1 with detection limits of 0.408 μg·L−1 and 0.453 μg·L−1 for lead and cadmium ions, respectively. The produced electrodes have good reproducibility with relative standard deviations of 4.65% for lead and 4.36% for cadmium ions. The results demonstrate that this simple, stable, and sensitive sensor is suitable for the simultaneous electrochemical determination of Pb2+ and Cd2+ at trace levels. [ABSTRACT FROM AUTHOR]