查看更多>>摘要：A novel dicyanoisophorone-based red-emissive fluorescence probe (YT) with large Stokes shift (230 nm) was synthesized for rapid (<20 s) and selective detection of hypochlorite ions in nearly 100% aqueous medium. YT responded to hypochlorite ions via the ClO--promoted oxidative deprotection of thioacetal, leading to a red shift in its fluorescence maximum from 590 nm to 640 nm accompanied by naked-eye color change from orange to red. The emission response of the probe toward ClO- presented a good linear relationship in the 5-160 mu M concentration range, with the LOD of 4.64 mu M. Further, the probe YT was successfully employed in exogenous and LPS-induced endogenous imaging of ClO- in live cells and zebrafish, demonstrating its potential applications in biological science.
查看更多>>摘要：A flexible dual functional electrochemical sensor based on macroscopic polyaniline (PANI) film is reported. The PANI film is prepared by interfacial synthesis without any additional templates and surfactants, and is easily transferred from the water surface to any substrate. The surface of PANI film is flat and has a certain degree of crystallization. The PANI film exhibits good electrochemical properties, which is attributed to the order structure of PANI. The flexible sensor based on PANI film exhibits good electrochemical performances to pH and lactate. And the flexible PANI sensor has good reproducibility, selectivity and long-term stability. Meanwhile, the PANI sensor is also applied to detect the actual sample (such as food and human sweat), and the results are in accordance with the commercial pH meter, indicating the reliability of the PANI sensor.
查看更多>>摘要：Recently, there has been growing interest in short-chain fatty acids (SCFA) and ketone bodies (KB) due to their potential use as biomarkers of health and disease. For instance, these diet-related metabolites can be used to monitor and reduce the risk of immune response, diabetes, or cardiovascular diseases. Given the interest in these metabolites, different targeted metabolomic methods based on UPLC-MS/MS have been developed in recent years to detect and quantify SCFA and KB. In this case study, we discovered that applying an existing validated, targeted UPLC-MS/MS method to mouse plasma, resulted in a fragment ion (194 m/z) being originally misidentified as acetic acid (a SCFA), when its original source was 3-hydroxybutyric acid (a KB). Therefore, we report a modified, optimized LC method that can separate both signals. In addition, the metabolite coverage was expanded in this method to detect up to eight SCFA: acetic, propanoic, butyric, isobutyric, 2-methylbutyric, valeric, isovaleric, and hexanoic acids, two KB: 3-hydroxybutyric, and acetoacetic acids, and one related metabolite: 3-hydroxy-3-methylbutyric acid. The optimization of this method increased the selectivity of the UPLC-MS/MS method towards the misidentified compound. These findings encourage the scientific community to increase efforts in validating the original precursor of small molecule fragments in targeted methods.
查看更多>>摘要：Virus surveillance and discovery are crucial for virus prediction and outbreak preparedness. Virus samples are frequently bulky and complicated so that effective virus detection remain challenging. Herein, we develop an 3D electrostatic microfluidic platform to rapidly and label-free enrich viruses from bulky samples at low concentrations. The platform consists of double microchannels for streamlining large volume processing and electrodes for enriching viruses by electrostatic interaction. The trajectories of simulation show that particle is successfully enriched under different forces of electrostatic field and different sample flow rates. We demonstrate that the electrostatic microfluidic platform can increase the limit of detection in 100-fold higher based on real-time PCR quantified analysis. Our design thus provides a simple, rapid, label-free and high-throughput viruses concentration platform and would thus have significant utility for various viral detection.
查看更多>>摘要：This paper reports the non-targeted analysis of unknown volatile components in scented stationery based on headspace gas chromatography-Orbitrap high-resolution mass spectrometry. The volatiles released from the samples (22 scented erasers and 17 scented pens) under specific headspace conditions were analyzed. A qualitative analysis of unknown substances was carried out according to four identification steps (step 1: comprehensive score and retention index, step 2: identification of molecular ion peaks by chemical ionization, step 3: fragment ion detail comparison for distinguishing isomers, step 4: verification by chemical standards). A total of 101 volatile substances were identified in the scented erasers, and 86 volatile substances were identified in the scented pens. The identified substances were divided into eight categories. Aliphatic hydrocarbons, aromatic hydrocarbons, esters, and alcohols were the top four groups of substances identified in scented erasers and pens. The identified substances were further filtered and screened according to their detection rate, toxicity, and response intensity. Finally, 14 high-risk volatile chemicals in scented stationery were listed. This study can be used as a reference for identifying unknown substances and as a guide for monitoring volatile chemicals in products and assessing their possible risks to consumers.
查看更多>>摘要：Electronically driven micromanipulation (EDM) with microscopic control was used as a novel tool for sample preparation prior to direct (matrix assisted) laser desorption/ionization mass spectrometric ((MA)LDI-MS) analysis of mature pea seed coat composition in defined layers. Microscissors were used for seed coat fragment shape adjustment, microtweezers for sample holding and "microjackhammer" Milling Pro for precise mechanical removing of cell layers in defined depths (2, 5 or 10 mu m). These procedures circumvent the application of embedding media or enzymatic digestion of seed coat that would complicate mass spectra interpretation (presence of matrix signals, analyte signals enhancement or attenuation) and represent alternative for 3D metabolites profiling. In addition, microinjector was used to apply a solution on intact or micropeeled seed coat surface in nano-volumes, i.e. MALDI matrix and/or lithium salt, that provide improvement of signal of sugars. Utilization of EDM enabled optimization of matrix composition on a single small fragment of seed coat overcoming thus problems with biological (seed to seed) variability. LDI-MS data were studied by multivariate statistical analysis and significant metabolites in particular layers of seed coats were identified. Normalized intensities of signals (NS) of long-chain hydroxylated fatty acids (HLFA) on intact dormant pea genotype (JI64) seed coats were significantly higher than in their counterparts treated by micropeeling confirming HLFA accumulation in outermost layers (cutin). Fatty acids distribution differences between dormant and non-dormant genotypes were explored in detail. On the other hand, NS of sugar chains and particular polyphenols were significantly higher in micropeeled seed coats of studied dormant and non-dormant genotypes than in intact seed coats. Furthermore, combination of EDM with mass spectrometry imaging (MSI) allowed vertical profiling of metabolites in hilum (a place of former attachment of seed to maternal plant) and comparison of its composition with surrounding tissues. The obtained results contribute to the understanding of relations between seed coat chemical composition and physical seed dormancy.
查看更多>>摘要：As a new type of carbon nanomaterial, graphdiyne (GDY) has unique sp hybridized carbon atom, which makes it possible to develop new nitrogen-doped configurations. In this paper, sp-hybridized nitrogen atom doped ultrathin graphdiyne (NUGDY) was prepared based on graphdiyne oxide and melamine by carbonization at high temperature. NUGDY not only preserves the typical folded and wrinkled two-dimensional morphology of GDY, but also presents a three-dimensional porous network structure, which provides sufficient interface and capacity for the loading of target analyte. Meanwhile, N doping increases the GDY defects with more active sites and higher conductivity. Then, NUGDY was modified on the surface of carbon ionic liquid electrode and the modified electrode was applied to 6,7-dihydroxycoumarin (6,7-DHC) analysis. Cyclic voltammetry, electrochemical impedance spectroscopy and chronocoulometry results show that NUGDY has good promotive effect to the electrode performances. Differential pulse voltammetric experiments show that this electrochemical sensor has a low detection limit as 2.3 nM (3S(0)/S) for 6,7-DHC with high sensitivity. In addition, the modified electrode has the characteristics of excellent anti-interference ability and stability, and been successfully used in the real samples determination, which provides a promising method for the sensitive detection of drug molecules.
查看更多>>摘要：Circulating miR-195-5p has been proposed as a promising peripheral biomarker for the diagnosis, prognosis and severity assessment of various diseases. However, the demand for its sensitive and convenient quantification has not been met yet. Herein, we proposed a one-pot isothermal approach, in which the target signal acquisition, amplification and conversion (fluorescence read-out) system was integrated by a triple strand displacement amplification (SDA) cascade. Using this triple SDA strategy, miR-195-5p can be at least detected at 1 aM, and the linear dynamic range (from 100 aM to 1 pM) is wide enough to meet the detection needs of clinical miRNA level. A proof-of-principle study, using this novel methodology to directly analyze the spiking serum samples with different levels of miR-195-5p, demonstrated the potential of circulating miR-195-5p detection for clinical point of-care assay. This one-pot isothermal triple SDA approach, we believe, will be a simple and feasible tool for ultrasensitive quantification of circulating miR-195-5p, and may promote the wide application of this potential biomarker in non-invasive clinical diagnosis.
查看更多>>摘要：Duplex specific nuclease (DSN) that can precisely cleave DNA portion in double-stranded DNA or DNA-RNA hybrid has engrossed immense attention owing to its great potential in emerging bioanalytical applications. Here, we present a novel approach to extend DSN sensing application by coupling RNA aptamer. Specially designed RNA ligand sequences are used to capture the target and simultaneously provide complementary sequences of DNA for DSN aided fluorescent signal enhancement. A clotting enzyme, thrombin, has been used as a model analyte. One RNA aptamer combined with the target molecule can generate fluorescent signals through cleavage of hybridized TaqMan DNA probe (P2) by DSN. The proposed assay has achieved the lowest detection limit of 0.039 pM. The assay has been applied for real-time detection of thrombin release from live cells and other biotic media for early disease diagnosis. The developed method is versatile and can detect various other targets by choosing the relevant aptamer and probe sequences. This method is promising to be applied to medical diagnosis, biosensing, food safety, environmental monitoring, and other fields.
查看更多>>摘要：Matrix-assisted laser desorption ionization mass spectrometry (MALDI MS) and imaging mass spectrometry (IMS) are being increasingly recognized for the detection and visualization of various organic species including lipids and fatty acids. Nevertheless, most MALDI matrices perform optimally in one ionization mode. This study investigates the performance of cyano derivative of graphene (G-CN) as a matrix in two polarities of MALDI MS and IMS for the detection of oil binders and fatty acids in artworks, and compares it with classical MALDI matrices (2,5-dihydroxybenzoic acid, 9-aminoacridine). Results revealed the ability of G-CN to provide high quality positive and negative mass spectra of oils and fatty acids, respectively, with lowest matrix-induced interferences among tested matrices and minimal effects of the presence of inorganic pigments. The newly developed approach makes both oil and fatty acid identifiable in a single spot simply by covering the sample surface with one matrix and switching the polarity in MALDI without any sample manipulation. G-CN offers effective matrix to analyte energy transfer, ability to detect components in less than 100 ng of oil at a MALDI spot and lesser analyte fragmentation than the compared conventional matrices. Furthermore, it enables direct mapping of specific m/z features corresponding to triacylglycerol (TAG), products of TAG oxidation and deprotonated acids using one nanoparticle matrix in MALDI IMS. This research shows potential for technical innovations in the study of art micro-environments and degradation phenomena of historical artworks.
NSTL
Elsevier