查看更多>>摘要：Insufficient acetylcholine (ACh) can cause cognitive and memory dysfunction, clinically known as, Alzheimer's disease (AD). Acetylcholinesterase (AChE) can hydrolyze ACh into acetic acid and inactivate choline. Therefore, inhibiting the activity of AChE would help to improve the effectiveness of AD treatment. Currently, the methods for rapid screening of AChE inhibitors are limited. This study reports the application of AChE-immobilized magnetic nanoparticles as a drug screening tool to screen AChE inhibitors for natural products. First, AChE was immobilized on a surface of amino-modified magnetic nanoparticles using covalent binding and the AChE concentration, and the pH as well as time was optimized to obtain the maximum enzyme immobilization yield (61.4 mu g/mg), and the kinetic model indicated that AChE-immobilized magnetic nanoparticles and the substrate had the high affinity and specificity. Then, a ligand fishing experiment was carried out using a mixed model of tacrine (an inhibitor of AChE) and caffeic acid (a non-inhibitor of AChE) to verify the specificity of the immo-bilized AChE, and the conditions for ligand fishing were further optimized. Finally, the optimized immobilized AChE was combined with UPLC-MS to screen for AChE inhibitors in Selaginella doederleinii Hieron extracts. Four compounds were confirmed to be potent AChE inhibitors. Among the four compounds, amentoflavone had a stronger AChE inhibitory effect than tacrine (positive control) with an IC50 of 0.73 +/- 0.009 mu mol/L. The results showed that AChE-functionalized magnetic nanoparticles can be used in the discovery of target drugs from complex matrices.
查看更多>>摘要：The analysis of toxic and harmful substances in food has attracted significant attention. In this work, a molecularly imprinted column coupled to gas chromatography-triple quadrupole tandem mass spectrometry method (MIC-GC-MS/MS) method for the determination of 16 polycyclic aromatic hydrocarbons (PAHs) in takeaway meal boxes was established by comparing the extraction results of 16 PAHs with 5 different sample pretreatment techniques, and the effects of food types and storage conditions on the migration of PAHs was studied by migration test. The conditions of extraction and chromatography-mass spectrometry were optimized. The results showed that the linear ranges were in the wide range of 1-100 ng mL(-1) for 16 PAHs, with the correlation coefficients (R) higher than 0.9983; the detection limits (LODs) and the limits of quantification (LOQs) were in the range of 0.08-0.42 mu g kg(-1) and 0.24-1.26 mu g kg(-1), respectively; the spiked recoveries at three levels of 10, 20, 30 mu g kg(-1) were in the range of 86.2%-107.7% with the relative standard deviation (RSD) less than 7.8%. Therefore, this method had high sensitivity and good reproducibility and was suitable for the determination of 16 PAHs in food contact materials. The migration test of PAHs showed that the migration amount of PAHs in takeaway meal boxes was closely related to food types, and the migration amount was positively correlated with contact temperature and contact time in a certain range.
查看更多>>摘要：Mass spectrometry is uniquely suited to identify and quantify environmentally relevant molecules and molecular clusters. Mass spectrometry alone is, however, not able to distinguish between isomers. In this study, we demonstrate the use of both an experimental set-up using a differential mobility analyser, and computational ion mobility calculations for identification of isomers. In the experimental set-up, we combined electrospray ionisation with a differential mobility analyser time-of-flight mass spectrometer to separate environmentally relevant constitutional isomers, such as catechol, resorcinol and hydroquinone, and configurational isomers, such as cyclohexanediols and fatty acids (i.e., oleic and elaidic acids). Computational ion mobility predictions were obtained using the Ion Mobility Software (IMoS) program. We find that isomer separation can be achieved with the differential mobility analyser, while for catechol, resorcinol and hydroquinone, the computational predictions can reproduce the experimental order of the ion mobilities between the isomers, confirming the isomer identification. Our experimental set-up allows analysis both in the gas and liquid phase. The differential mobility analyser can, moreover, be combined with any mass spectrometry set-up, making it a versatile tool for the separation of isomers.
Duque, AlaineGrau, JoseBenede, Juan L.Alonso, Rosa M....
10页
查看更多>>摘要：In this work, a low toxicity deep eutectic solvent-based ferrofluid is presented for the first time as magnetic fluid to be used as an efficient solvent in liquid-based microextraction techniques. This ferrofluid is made of a hy-drophobic deep eutectic solvent, composed by menthol and thymol in a 1:5 molar ratio as carrier solvent, and oleic acid-coated cobalt ferrite (CoFe2O4@oleic acid) magnetic nanoparticles. This material was characterized via magnetism measurement, scanning electron microscopy, infrared spectroscopy and density measurement. The determination of UV filters in environmental water samples was selected as model analytical application to test the extraction performance of this new ferrofluid by employing stir bar dispersive liquid microextraction, prior to liquid chromatography-tandem mass spectrometry analysis. The response surface methodology was used as a multivariate optimization method for extraction step. Under the optimized conditions, good analytical features were obtained, such as low limits of detection between 7 and 83 ng L-1, good repeatability (relative standard deviations, RSD (%) below 15%), enrichment factors between 46 and 101 and relative recoveries be-tween 80 and 117%, proving the good extraction capability of this ferrofluid. Finally, the method was successfully applied to three environmental waters (beach and river waters), finding trace amounts of the target UV filters. The presented low toxicity deep eutectic solvent-based ferrofluid results to be a good alternative to conventional solvents used in liquid-phase microextraction techniques.
查看更多>>摘要：Based on hybridization chain reaction (HCR) and fluorescence synergism, a novel aptasensor for tobramycin was successfully constructed. Tobramycin competed with cDNA-FAM to bind aptamers immobilized on magnetic beads. After magnetic separation, the released cDNA-FAM acted as initiator to trigger HCR amplification, thus the fluorescence was significantly enhanced due to binding of SYBR Green I (SGI) to the formed long doublestranded DNA and the synergistic fluorescence of FAM. In the absence of tobramycin, the initiator was magnetically separated and no HCR occurred, more importantly, graphene oxide can quench the fluorescence of excessive hairpins/SGI and cDNA-FAM, so almost no background signal was detected. This aptasensor can monitor tobramycin in the range of 0.3-50 mu M with low detection limit of 17.37 nM. Due to the potential generality of structure-switching aptamers and effectiveness of fluorescence synergism, this enzyme-free amplification strategy can be extended to other applications by rational design of nucleic acid sequences.
查看更多>>摘要：Helicobacter pylori infections are threats to public health due to their high infection rate and drug resistance. Identification of single-nucleotide variants (SNVs) in H. pylori is crucial for both diagnosis and therapy. Yet the clinical testing of resistant H. pylori mutants is still facing some challenges, such as the selectivity is not good enough for SNVs in abundant wild-type DNA, the lack of clinical validation and the economical burden on patients. Herein, an X-shaped DNA probe with a toehold initiator was designed, which could specifically hybridize with certain genotype DNA due to the thermodynamically driven reaction. A competitive reaction was developed to amplify the thermodynamic difference between wild-type DNA and SNVs, diminishing the interference of wild-type DNA. By this means, multiple SNVs in H. pylori were successfully identified and two SNVs related to clarithromycin resistance are chosen as model targets. A paper strip was fabricated for visual, fast screening of SNVs. Furthermore, the approach was validated using clinical samples, and a point-of-care (POCT) testing diagnosis was executed on saliva samples, demonstrating its potential for the prevention and cure of H. pylori infections.
查看更多>>摘要：Carbamazepine (CBZ) and its metabolite carbamazepine-10,11-epoxide (CBZEP) play vital role in the treatment of epilepsy. It is of great importance to develop a method for rapid and sensitive monitoring of CBZ and CBZEP due to their narrow therapeutic index. Herein, an imine-linked-based covalent organic framework was synthesized by using 1,3,5-tris (4-aminophenyl) benzene (TPB) and 1,3,5-triformylbenzene (TFB) (denoted as TPB-TFBCOF),and applied as a solid-phase microextraction (SPME) probe for extracting CBZ and CBZEP. The TPB-TFBCOF showed large surface areas (371 m(2) g(-1)), high regular porosity (1.23 nm) and extraordinary stability, which rendered it an ideal adsorbent for highly efficient enrichment of CBZ and CBZEP. Accordingly, an attractive strategy of the combination of the TPB-TFB-COF-based SPME probe and electrospray ionization mass spectrometry system (ESI/MS) was proposed for rapid screening and sensitive monitoring of CBZ and CBZEP. Under the optimized parameters, the developed method exhibited good linearity for CBZ and CBZEP in the range of 4-1000 mu g Lg(-1) with correlation coefficient (r) no less than 0.9953, and the corresponding limits of detection (LODs) were 0.4 and 2.5 mu g Lg(-1), respectively. Moreover, high enrichment factors (EFs, 202-351 folds) and satisfactory relative standard deviations (RSDs) of one probe (3.3-5.1%) and probe-to-probe (4.8-5.6%) were obtained. By using the proposed method, sensitive screening and quantitative evaluation of CBZ and CBZEP in mice whole blood and tissue homogenates were successfully achieved, indicating the promising applicability of the TPB-TFB-COF-SPME-AMIS as a powerful tool for drug monitoring.
查看更多>>摘要：Chiral recognition is of highly interest in the areas of chemistry, pharmaceuticals, and bioscience. An effective strategy of enantiomeric determination of amino acids (AAs) was developed in this work. All 19 natural AAs enantiomers can be easily distinguished by ion mobility-mass spectrometry of the non-covalent complexes of AAs with cyclodextrins (alpha-CD, beta-CD and gamma-CD) and Mg2+ without any chemical derivatization. Differences of the mobilities between the enantiomers' complexes is from 0.006 to 0.058 V s/cm(2). In addition, the complex of [beta-CD + Phe + Mg](2+) was selected as an example to study the relative quantification by measuring L/D-Phe at different molar ratio of 10:1 to 1:10 in the mu M range, resulting in a good linearity (R-2 > 0.99) and high sensitivity at 2 mu M. A DFT calculation was also performed to illustrate the detailed molecular structure of the complexes of CDs, Mg2+ and D-or L-Phe. Both experiment and theoretical calculation showed that Mg2+ plays an important role in host/guest interactions, which changed the molecular conformations by non-covalent interaction between Mg2+ and CDs, and resulted in the different collision cross-sections of the complex ions of CDs, Mg2+ and D-or LAAs in the gas phase. This effective and convenient strategy could potentially be utilized in scientific research and industry for routine enantiomeric determination of natural AAs, peptides and some other small chiral biomolecules such as non-natural AAs and carboxylic acid-containing drugs.
查看更多>>摘要：The ability of cyclodextrins to enhance the water solubility of lipophilic compounds is used to modify the water-based Oxygen Radical Absorbance Capacity (ORAC) method to measure antioxidant activity in vitro. However, the use of these solubility enhancers may alter fluorescent readings, which has led to contradictory results being described in the literature. The low specificity of these oligosaccharides and their controlled release effect can result in cyclodextrins forming inclusion complexes with other reagents in the assay, changing the kinetics. In this study, the cause of cyclodextrins' interference in the ORAC method is evaluated through a physicochemical and computational approach. Cyclodextrins showed a clear increase in the fluorescent signal both in the presence and absence of the antioxidant oxyresveratrol, the precise effect being dependent on the type and concentration of cyclodextrin. Although the glucidic nature of cyclodextrins could play a minimal role in this effect, it seems that the main cause was the encapsulation of other substrates in the reaction, fluorescein and AAPH.
查看更多>>摘要：Protein N-phosphorylation is increasingly recognized as a critical post-translational modification in central metabolism and cell signaling. However, other functions of N-phosphorylation in organism are largely unexplored which is attributed to lack high efficient enrichment methods. To address this, Bis(zinc(II)-dipicolylamine) functionalized graphene oxide nanocomposites (Zn(II)-DPA-GO) was designed via loading bis(zinc(II)dipicolylamine) (Zn(II)-DPA) on graphene oxide surface by 7C-7C stacking, with the advantages of large immobilization amount of Zn(II)-DPA, layered structure, excellent solubility and low non-special adsorption. The material was firstly verified excellent enrichment ability for standard proteins and E.coli lysates. By integrating the enrichment method into proteomics workflow, 36 N-phosphoproteins functioned in metabolic process, biological regulation, localization, cellular processes were identified from Bacillus subtilis. Furthermore, motif analysis showed that leucine and isoleucine were enriched near the sites, providing potential clues for the discovery of new sites. The method provides an alternative for the discovery of N-phosphoproteins with significant biological functions.
NSTL
Elsevier