Ladefogedcarstensen0462

Point-of-care (POC) diagnostic devices play significant roles in delivering vital surveillance information and providing proper and timely care to patients. There is a challenge in the development of new diagnostic tools to overcome their current shortcomings in terms of cost issues, accuracy and performance. Herein, a highly efficient paper-based analytical device based on a 2D metal-organic framework (MOF) has been reported for the colorimetric/fluorometric monitoring of glucose. Because of the inherent bifunctional activity of cobalt-terephthalate MOF (CoMOF) nanosheets, great improvements were made to the stability and performance of glucose oxidase (GOX) and to its catalytic effect on the reaction of o-phenylenediamine (OPD) and H2O2. The exceptional behavior of 2D CoMOF, along with a precise smartphone readout, led to the rapid and sensitive colorimetric/fluorometric detection of glucose in biological samples. Paper modified by CoMOF and GOX was stable for a long time, and a yellow-brown color and a high fluorescence emission were observed after the addition of a low volume of sample and OPD solutions. selleck chemicals The probe showed a wide linear effectiveness range of 50 μM-15 mM, with colorimetric and fluorometric detection limits of 16.3 and 3.2 μM, respectively. Despite its great simplicity, the developed probe showed high performance and accuracy for the quantification of glucose.We present an approach for the elucidation of C=C bond position and cis/trans isomers, which is achieved by the reaction of ambient water radical cations and double bonds, followed by the fragmentation of epoxide radical cations to generate diagnostic ions in tandem mass spectrometry. Hexenol double bond positional isomers and cis/trans isomers which exhibit different properties and biological functions are characterized as a proof of concept. The merits of the approach include the simplicity of experimental setup, rapid derivatization (within seconds), the obviation of organic solvents, as well as easy spectral interpretation.The detection of Salmonella Typhimurium (S.typhimurium) is of great importance in food safety field. Colorimetric strategy is particularly appealing for S. typhimurium identification because of its user-friendliness and instrument-free. However, the existing colorimetric strategies still meet the challenges of low sensitivity, tedious nucleic acid extraction and expensive labeling processes. Herein, a high sensitivity and label-free colorimetric sensing strategy for S. typhimurium detection without nucleic acid extraction is constructed. Specifically, the proposed strategy is based on three-way junction (3WJ) DNA branched structure combined with nicking enzyme signal amplification (NESA). In the presence of target, cascaded signal amplification is initiated through a series of toehold-mediated strand displacement reactions (TSDRs) to recycle the trigger DNA causing formation of the numerous 3WJ DNA branched structures (3WJ-TSDRs). Then, the branches of 3WJ-TSDRs are fully utilized to hybridize with the DNAzyme signal probes to initiate NESA in the presence of Nt. BbvCI, which making every branch has a function of signal amplification. Finally, DNAzyme signal probes (green) were completely split into two fragments (colorless). The application of NESA in the branches of 3WJ-TSDRs offers a highly sensitive detection of S. typhimurium with a low limit of detection of 42 CFU mL-1. Besides, the colorimetric sensing strategy also shows strong anti-interference. The capability of the colorimetric sensing strategy in spiked samples was also investigated, showing a more intuitive results and fast detection in compare with the traditional plate counting method. With these characteristics, the proposed sensing strategy based on 3WJ-TSDRs and NESA is a promising tool for new point-of-care (POC) applications in food safety.We demonstrate a new electroanalytical technique using nanoemulsions (NEs) as a nanoextractor combined with single entity electrochemistry (SEE) to separate, preconcentrate analytes from bulk media, and even detect them in situ, enabling ultratrace level analysis. This approach is based on our hypothesis that the custom-designed NEs would enable to effectively scavenge compounds from bulk media. Herein, we use Pluronic F-127 functionalized NEs to extract, preconcentrate target analytes e.g., ferrocene derivatives as a model aromatic toxicant dissolved in the water, and employ SEE to in situ detect and quantitatively estimate analytes extracted in individual NEs. Extraction was markedly efficient to reach ∼8 orders of magnitude of preconcentration factor under the true equilibrium, thereby enabling ultratrace level analysis with a detection limit of ∼0.2 ppb. The key step to attain high sensitivity in our measurements was to modulate the total amount of added NEs respect to the total volume of bulk solution, thereby controlling the extracted amount of analytes in each NE. Our approach is readily applicable to investigate other aromatic toxicants dissolved in the water, thus detecting hazardous carcinogen, 2-aminobiphenyl in the water up to ∼0.1 ppb level. Given the excellent detection performance as well as the broad applicability for ubiquitous aromatic contaminants, the combination of NEs with SEE offers great prospects as a sensor for environmental applications.Several novel non-typical nucleoside analogs were examined as potential fluorescent indicators of purine-nucleoside phosphorylase (PNP) activity in human blood. The substrates included N7-riboside of 8-aza-2,6-diaminopurine, N6-riboside of 1,N6-etheno-adenine and N2-riboside of N2,3-etheno-2-aminopurine. Reaction rates and apparent Michaelis' constants were determined in 1000-fold blood lysates and compared with those for reference compounds, guanosine and 7-methylguanosine. It was concluded that the most promising for assaying human PNP in biological material was N6-riboside of 1,N6-etheno-adenine and N2-riboside of N2,3-etheno-2-aminopurine was optimal for the E. coli PNP, both offering at least 10-fold improvement in sensitivity relative to conventional assays. Other potential applications of this approach are discussed.