A fluorometric and colorimetric dual-modal nanoprobe (denoted as Fe
2+
-Phen/SiNPs) has been developed for selective and sensitive determination of nitrite (NO
2
−
). The mechanism is based on ...fluorescence quenching between silicon nanoparticles (SiNPs) and Fe(II)-phenanthroline complex (Fe
2+
-Phen) via inner filter effect and redox. With the addition of increasing NO
2
−
, Fe
2+
is oxidized to Fe
3+
, recovering the fluorescence of SiNPs. Meanwhile, the color of the system gradually changes from orange-red to colorless, which enables colorimetric measurement. The NO
2
−
concentration shows a wide linear relationship with fluorescence intensity from 0.1 to 1.0 mM (
R
2
= 0.9955) with a detection limit of 2.4 μM in the fluorometric method (excitation wavelength: 380 nm). By contrast, the linear range of the colorimetric method ranges from 0.01 to 0.35 mM (
R
2
= 0.9953) with a limit of detection of 6.8 μM (proposed selective absorbance: 510 nm). The probe has been successfully applied to nitrite determination in water, salted vegetables, and hams demonstrating broad application prospects for the determination of nitrite in complicated matrices.
Graphical Abstract
A new detection platform based on a hydroxylated covalent organic framework (COF) integrated with liquid chromatography–tandem mass spectrometry (LC–MS/MS) was constructed and used for detecting ...adrenergic receptor agonists (ARAs) residues in milk. The hydroxylated COF was prepared by polymerization of tris(4-aminophenyl)amine and 1,3,5-tris(4-formyl-3-hydroxyphenyl)benzene and applied to solid-phase extraction (SPE) of ARAs. This hydroxylated COF was featured with hierarchical flower-like morphology, easy preparation, and copious active adsorption sites. The adsorption model fittings and molecular simulation were applied to explore the potential adsorption mechanism. This detection platform was suitable for detecting four α
2
- and five β
2
-ARAs residues in milk. The linear ranges of the ARAs were from 0.25 to 50 µg·kg
−1
; the intra-day and the inter-day repeatability were in the range 2.9–7.9% and 2.0–10.1%, respectively. This work demonstrates this hydroxylated COF has great potential as SPE cartridge packing, and provides a new way to determine ARAs residues in milk.
Graphical Abstract
In this paper, we propose a decentralized adaptive control scheme for a class of interconnected nonlinear systems without
a priori
knowledge of subsystems’ control directions and unknown actuator ...failure. To address this problem, a novel Nussbaum-type function is proposed and a key theorem is drawn which involves quantifying the interconnections of multiple Nussbaum-type functions of the subsystems with different control directions in a single inequality. The effect of actuator failures is successfully compensated. Global stability of the closed-loop system and asymptotic stabilization of subsystems’ output are proved and a simulation example is given to illustrate the effectiveness of the proposed control scheme.
In the intrinsic pathway of apoptosis, stresses of mitochondrial reactive oxygen species （mitoROS） might be sensed as more effective signals than those in cytosol, as mitochondria are the major ...sources of reactive oxygen species （ROS） and pivotal components during cell apoptosis. Mitochondrial superoxide dismutase （SOD2） takes the leading role in eliminating mitoROS, and inhibition of SOD2 might induce severe disturbances overwhelming the mitochondrial oxidative equilibrium, which would elevate the intracellular oxidative stresses and drive cells to death. Herein, we report a general strategy to kill cancer cells by targeted inhibition of SOD2 using 2-methoxyestradiol （2-ME, an inhibitor for the SOD family） via a robust mitochondria-targeted mesoporous silica nanocarrier （mtMSN）, with the expected elevation of mitoROS and activation of apoptosis in HeLa cells. Fe304@MSN was employed in the mitochondria-targeted drug delivery and selective inhibition of mitochondrial enzymes, and was shown to be stable with good biocompatibility and high loading capacity. Due to the selective inhibition of SOD2 by 2-ME/mtMSN, enhanced elevation of mitoROS （132% of that with free 2-ME） was obtained, coupled with higher efficiency in initiating cell apoptosis （395% of that with free 2-ME in 4 h）. Finally, the 2-ME/mtMSN exhibited powerful efficacy in targeted killing of HeLa cells by taking advantage of both biological recognition and magnetic guiding, causing 97.0% cell death with only 2 Dg/mL 2-ME/mtMSN, hinting at its great potential in cancer therapy through manipulation of the delicate mitochondrial oxidative balance.
Regional anesthesia has anti-proliferative and pro-apoptotic effects in various cancers. Therefore, the purpose of this study was to investigate the effects of ropivacaine on the proliferation, ...migration, invasion, and apoptosis of glioma cells
.
Under ropivacaine stimulation conditions, proliferation, apoptosis, migration, and invasion of glioma cells were determined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2
-tetrazol-3-ium bromide (MTT), flow cytometry, and transwell assays, respectively. Western blot assay was employed to measure the protein expression levels in glioma cells. The expression levels of small nucleolar RNA host gene 16 (SNHG16) and miR-424-5p were assessed by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The interaction relationship between SNHG16 and miR-424-5p was predicted and confirmed using a bioinformatics database and dual-luciferase reporter, RNA immunoprecipitation (RIP) and RNA pull-down assays.
After treatment with ropivacaine, proliferation, migration, and invasion were repressed while apoptosis was enhanced in glioma cells in a dose-depended manner. In addition, ropivacaine impeded SNHG16 expression in glioma cells. Importantly, overexpression of SNHG16 abolished the ropivacaine-induced effects on glioma cells. Analogously, knockdown of miR-424-5p counteracted the function of ropivacaine in glioma cells. We also found that SNHG16 bound to miR-424-5p and negatively regulated miR-424-5p expression in glioma cells. The rescue experiments indicated that ropivacaine might regulate glioma progression by targeting the SNHG16/miR-424-5p axis.
Our findings revealed the anti-tumor effects of ropivacaine in glioma by targeting the SNHG16/miR-424-5p axis. These data might extend the understanding of regulatory mechanisms by which ropivacaine could suppress glioma development.
•TAPA-TFPB-COFs was simply synthesized at room temperature.•TAPA-TFPB-COFs were explored as sorbents for the SPE of PCAs.•The established SPE-HPLC-MS/MS method was sensitive and accurate.•This method ...satisfied the analyzation of PCAs in environmental water samples.
The determination of traces levels of pesticide residue in water is crucial for monitoring water quality. In this study, covalent organic frameworks (COFs), namely TAPA-TFPB-COFs were prepared at room temperature (25 °C) and applied as adsorbents for the solid phase extraction (SPE) of phenoxy carboxylic acid herbicides (PCAs). The extraction was followed by analyzation using liquid chromatography-tandem mass spectrometry (LC-MS/MS). Under the optimal conditions, ultrasensitive and specific analysis of PCAs in water samples was achieved. The method exhibited high sensitivity with low limits of detection (0.08–0.28 ng L−1), good linearity in the range of 1.00 to 200 ng L−1 and satisfactory repeatability (intra-day: 3.72–5.30%; inter-day: 2.02–4.04%). The method was successfully applied to the analyzation of trace PCAs in tap, well, and river water and the spiked recoveries were in the range of 81.1–112%. These results indicate that the SPE-LC-MS/MS technique with TAPA-TFPB-COFs as the SPE adsorbent is a promising technique for the detection of trace levels of PCAs in environmental water samples.
•A novel magnetic covalent organic framework (NH2–Fe3O4@COF) was synthesized and used as a MSPE adsorbent.•Adsorption mechanism of benzoylurea insecticides (BUs) on NH2–Fe3O4@COF was elucidated by ...DFT study.•Low limits of detection, good precision, and wide linearities were obtained by the proposed MSPE–LC–MS/MS method.
A novel magnetic covalent organic framework (NH2–Fe3O4@COF) was prepared using a simple room-temperature synthesis in this study. These magnetic particles exhibited high adsorption performance with short adsorption time (10 min) for six benzoylurea insecticides (BUs) as magnetic solid-phase extraction (MSPE) adsorbents. Quantum chemistry calculation demonstrated that adsorption mechanism was primarily attributed to strong halogen bonds between electronegative O atoms of COF and electropositive F atoms of BUs as well as potential hydrophobic effect. Wide linearities (10–1000 ng·L−1) and low limits of detection (0.06–1.65 ng·L−1) for six analytes were obtained via liquid chromatography–tandem mass spectrometry. Applicability of the proposed method was further evaluated by analyzing four kinds of original tea beverages. Recoveries of six BUs in spiked samples ranged from 80.1% to 108.4%.
In recent years, graphene-based magnetic composites have attracted tremendous research interest owing to its exceptional properties, such as huge surface area, large delocalized π-electron system, ...strong magnetic responsiveness, and excellent mechanical/thermal stability. These promising properties together with the ease of processibility and functionalization render graphene-based magnetic composites to be ideal adsorbents in magnetic solid-phase extraction. In this review, we outline the state of the art on the preparation approaches for different graphene-based magnetic composites and its application as adsorbents in preconcentrating organic compounds, biological macromolecules, and metal ions. In addition, future research directions of this type of magnetic materials are identified as well.
•Graphene-based magnetic solid-phase extraction (MSPE) was discussed.•The synthesis of different graphene-based magnetic composites (GMC) were reviewed.•Application of GMC as adsorbents for MSPE were summarized.•Future research directions of GMC were identified.
The facile fabrication of covalent organic frameworks (COFs) is significant for exploring and promoting their application. In this study, TAPA-TFPB-COFs with flower-shaped morphology, good ...crystallinity, and high surface area was prepared via a facile room-temperature method. The as-synthesized TAPA-TFPB-COFs exhibited great adsorption capacity towards quinolone antibiotics (QAs) and satisfying reusability. Utilizing the TAPA-TFPB-COFs as solid-phase extraction cartridge packing and liquid chromatography-tandem mass spectrometry as detector, a reliable and ultrasensitive method for the assay of QAs was developed. The linearity ranges of QAs extended from 0.5 to 200 ng L−1 with correlation coefficients higher than 0.9974, and the limits of detection varied from 0.02 to 0.11 ng L−1. The intra-day and inter-day precision were lower than 10.8% and 6.7%, respectively. The applicability of the developed method was evaluated through analyzing of tap water, spring water, chicken, and fish samples. The recoveries of QAs in spiked water and food samples varied from 80.0% to 107.6%. The reliability of the developed method was further verified by the accurate detection of QAs in a fish certified reference material.
•TAPA-TFPB-COFs was prepared by a facile room-temperature method.•TAPA-TFPB-COFs exhibited good extraction ability for quinolone antibiotics.•The developed SPE-LC-MS/MS method was reliable and ultrasensitive.•This method was suitable for analysis of quinolone antibiotics in water and meat.
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