共查询到20条相似文献,搜索用时 15 毫秒
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Stöckel S Meisel S Elschner M Rösch P Popp J 《Angewandte Chemie (International ed. in English)》2012,51(22):5339-5342
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Due to the dangerous nature of anthrax, the development of a cost-effective, sensitive and field-portable sensor for the anthrax biomarker--calcium dipicolinate (CaDPA)--is of exceptional significance for both military and civilian use. Herein, a flexible polymer-film-based ratiometric sensor for detecting CaDPA was demonstrated. A reference dye and a probe ligand were covalently immobilized onto the film surface through a highly selective and efficient "click chemistry" reaction. The reference dye, whose fluorescence intensity does not change with varying amounts of CaDPA, offers a non-interfering internal calibration. The ethylenediaminetetraacetic acid (EDTA)-based ligand binds with Eu(III) and serves as the probe. In the absence of CaDPA, the film sensor exhibited almost no red fluorescence because the Eu(III) ions themselves give no emission without sensitization by CaDPA owing to the small molar absorption coefficients of Eu(III) ions. The presence of CaDPA induces a significantly enhanced emission intensity of the sensor, and thereby enables the film as a ratiometric sensor for CaDPA. This sensor can selectively detect CaDPA in water with a detection limit of 100 nM. Moreover, this sensor exhibited strong anti-interfering capability, it can not only be used in milieus that contain various amino acids and some biologically-abundant cations, but can also be usable in some biological fluids such as urine and serum. This test-paper-like film sensor is suitable for portable field analysis and needs no extra protective measures during transport due to its flexibility, and it can easily be separated from the analyte solution after the detection. 相似文献
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Zhang X Young MA Lyandres O Van Duyne RP 《Journal of the American Chemical Society》2005,127(12):4484-4489
A rapid detection protocol suitable for use by first-responders to detect anthrax spores using a low-cost, battery-powered, portable Raman spectrometer has been developed. Bacillus subtilis spores, harmless simulants for Bacillus anthracis, were studied using surface-enhanced Raman spectroscopy (SERS) on silver film over nanosphere (AgFON) substrates. Calcium dipicolinate (CaDPA), a biomarker for bacillus spores, was efficiently extracted by sonication in nitric acid and rapidly detected by SERS. AgFON surfaces optimized for 750 nm laser excitation have been fabricated and characterized by UV-vis diffuse reflectance spectroscopy and SERS. The SERS signal from extracted CaDPA was measured over the spore concentration range of 10(-14)-10(-12) M to determine the saturation binding capacity of the AgFON surface and to calculate the adsorption constant (Kspore=1.7 x 10(13) M(-1)). At present, an 11 min procedure is capable of achieving a limit of detection (LOD) of approximately 2.6 x 10(3) spores, below the anthrax infectious dose of 10(4) spores. The data presented herein also demonstrate that the shelf life of prefabricated AgFON substrates can be as long as 40 days prior to use. Finally, these sensing capabilities have been successfully transitioned from a laboratory spectrometer to a field-portable instrument. Using this technology, 10(4) bacillus spores were detected with a 5 s data acquisition period on a 1 month old AgFON substrate. The speed and sensitivity of this SERS sensor indicate that this technology can be used as a viable option for the field analysis of potentially harmful environmental samples. 相似文献
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Dipicolinic acid (DPA) is an excellent marker compound for bacterial spores, including those of Bacillus anthracis (anthrax). Surface-enhanced Raman spectroscopy (SERS) potentially has the sensitivity and discrimination needed for trace DPA analysis, but mixing DPA solutions with citrate-reduced silver colloid only yielded measurable SERS spectra at much higher (>80 ppm) concentrations than would be desirable for anthrax detection. Aggregation of the colloid with halide salts eliminated even these small DPA bands but aggregation with Na2SO4(aq) resulted in a remarkable increase in the DPA signals. With sulfate aggregation even 1 ppm solutions gave detectable signals with 10 s accumulation times, which is in the sensitivity range required. Addition of CNS- as an internal standard allowed quantitative DPA analysis, plotting the intensity of the strong DPA 1010 cm(-1) band (normalised to the ca. 2120 cm(-1) CNS- band) against DPA concentration gave a linear calibration (R2 = 0.986) over the range 0-50 ppm DPA. The inclusion of thiocyanate also allows false negatives due to accidental deactivation of the enhancing medium to be detected. 相似文献
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Raghu K. Chitta Don L. Rempel Michael L. Gross 《Journal of the American Society for Mass Spectrometry》2009,20(10):1813-1820
We describe the use of H/D amide exchange and electrospray ionization mass spectrometry to study, in organic solvents, the
pentadecapeptide gramicidin as a model for protein self association. In methanol-OD, all active H’s in the peptide exchange
for D within 5 min, indicating a monomer/dimer equilibrium that is shifted towards the fast-exchanging monomer. H/D exchange
in n-propanol-OD, however, showed a partially protected gramicidin that slowly converts to a second species that exchanges nearly
all the active hydrogens, indicating EX1 kinetics for the H/D exchange. We propose that this behavior is the result of the
slower rate of unfolding in n-propanol compared with that in methanol. The rate constant for the unfolding of the dimer is the rate of disappearance of
the partially protected species, and it agrees within a factor of two with a value reported in literature. The rate constant
of dimer refolding can be determined from the ratio of the rate constant for unfolding and the affinity constant for the dimer,
which we determined in an earlier study. The unfolding activation energy is 20 kcal mol−1, determined by performing the exchange experiments as a function of temperature. To study gramicidin in an even more hydrophobic
medium than n-propanol, we measured its H/D exchange kinetics in a phospholipids vesicle and found a different H/D amide exchange behavior.
Gramicidin is an unusual peptide dimer that can exhibit both EX1 and EX2 mechanisms for its H/D exchange, depending on the
solvent. 相似文献
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Stephenson J;AOAC 《Journal of AOAC International》2005,88(1):202-203
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The development of a miniaturized ammonia sensor made using microsystem technology is described. Gas is sampled in a sampler comprising two opposite channels separated by a gas permeable, water repellent polypropylene membrane. Subsequently, the acid sample solution is pumped into a selector where an alkaline solution is added to ionize all sampled ambient acid gasses, resulting in an enhanced selectivity. In the selector, the ammonia can diffuse through a second membrane into a purified water stream where an electrolyte conductivity sensor quantifies the resulting ammonium concentration. The realized system is shown to be selective enough not to be influenced by normal ambient carbon dioxide concentrations. Experiments with a gas flow of 3 ml/min, containing ammonia concentrations ranging from 9.8 to 0.3 ppm in a nitrogen carrier flow, into a 15 μl/min sample solution flow and finally into a 5 μl/min purified water stream have been carried out and show that the system is sensitive to ammonia concentration below 1 ppm. 相似文献
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Microwave-accelerated metal-enhanced fluorescence: application to detection of genomic and exosporium anthrax DNA in <30 seconds 总被引:1,自引:0,他引:1
We describe the ultra-fast and sensitive detection of the gene encoding the protective antigen of Bacillus anthracis the causative agent of anthrax. Our approach employs a highly novel platform technology, Microwave-Accelerated Metal-Enhanced Fluorescence (MAMEF), which combines the use of Metal-Enhanced Fluorescence to enhance assay sensitivity and focused microwave heating to spatially and kinetically accelerate DNA hybridization. Genomic and exosporium target DNA of Bacillus anthracis spores was detected within a minute in the nanograms per microliter concentration range using low-power focused microwave heating. The MAMEF technology was able to distinguish between B. anthracis and B. cereus, a non-virulent close relative. We believe that this study has set the stage and indeed provides an opportunity for the ultra-fast and specific detection of B. anthracis spores with minimal pre-processing steps using a relatively simple but cost-effective technology that could minimize casualties in the event of another anthrax attack. 相似文献
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Zampolli S Betti P Elmi I Dalcanale E 《Chemical communications (Cambridge, England)》2007,(27):2790-2792
Micromachining technology is coupled to a selective pre-concentration material for the development of a portable sub-ppb level monitoring system for aromatic volatile organic compounds (VOC); the high sensitivity of Metal Oxide (MOX) gas sensors is combined with a supramolecular concentration unit to increase selectivity and reduce the detection limits. 相似文献
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Christina M. McGraw 《Talanta》2007,71(3):1180-1185
Miniaturization of analytical devices through the advent of microfluidics and micro total analysis systems is an important step forward for applications such as medical diagnostics and environmental monitoring. The development of field-deployable instruments requires that the entire system, including all necessary peripheral components, be miniaturized and packaged in a portable device. A sensor for long-term monitoring of phosphate levels has been developed that incorporates sampling, reagent and waste storage, detection, and wireless communication into a complete, miniaturized system. The device employs a low-power detection and communication system, so the entire instrument can operate autonomously for 7 days on a single rechargeable, 12 V battery. In addition, integration of a wireless communication device allows the instrument to be controlled and results to be downloaded remotely. This autonomous system has a limit of detection of 0.3 mg/L and a linear dynamic range between 0 and 20 mg/L. 相似文献
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Moazzez A. Fattahpour Najafi G. Ghobadian B. Hoseini S. S. 《Journal of Thermal Analysis and Calorimetry》2020,139(4):2553-2563
Journal of Thermal Analysis and Calorimetry - Efficient air-conditioning inside the cars is a challenge in automobile industry. Thermoelectric is one of the new methods for air cooling. It has many... 相似文献
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A part of the Zn-Mn-O phase diagram has been studied by using soft synthetic conditions and highly reactive precursors. This procedure allowed us to find and to isolate new single phases in the Zn-rich region. The new compounds are cubic spinels with a nominal composition Mn3−xZnxO4 with x=1.6 and 1.7. These spinels decompose upon heating giving rise to tetragonal distorted spinels. This survey is focused on the low-temperature region (T?700 °C) completing previous reports on the Zn-Mn-O phase diagram.We also report the magnetic properties of the new cubic spinels. These samples behave as paramagnets obeying a Curie-Weiss law in a broad temperature range. The effective paramagnetic moment agrees with the nominal mixture of Mn3+ and Mn4+ ions. However, randomness and competitive interactions give rise to the formation of spin-glass phases at very low temperature. 相似文献
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A new piezoelectric quartz crystal (PQC) sorption detector was developed to monitor carbon monoxide (CO) at sub-ppm level in ambient air. Out of the 28 coating materials studied, the palladium(II) acetamide complex with a 1:10 mole ratio of Pd(II) to acetamide was found to be the best. The detection is based on a non-reversible gas/coating interaction with sensitivity depending on gas flowrate. For 5-15 min exposure at a flowrate of 50 ml/min, the working ranges were found to vary from 0.7 to 40 ppm (total exposure from 8 to 160 μg CO) and detection limits (S/N=2) from 0.7 to 2 ppm CO (total exposure to 8 μg CO). The repeatability at 10 ppm CO was 11.8% (R.S.D. for n=3). The sensor lifetime was found dependent on exposure up to 160 μg CO or not exceeding 1000 Hz accumulative shift of frequency to avoid saturation of active sites at the crystal surface. No interference to CO detection was found for H2, H2S, SO2, NO2, CO2, HCHO, gasoline and water vapors at concentrations much higher than ambient air. Compared to existing CO monitor, the PQC detector developed has advantages of adequate selectivity, high sensitivity, fast response and a much lower detection limit for detecting CO at sub-ppm levels. However, it is limited by the total exposure to a maximum of 160 μg CO that restricts its application to intermittent monitoring of low CO concentration. The present work has demonstrated the advantages of using strong non-reversible interaction to enhance PQC sensitivity, as the total exposure can be adjusted easily by a suitable control of the gas flowrate. 相似文献
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Determination of formaldehyde and acetaldehyde in air by HPLC with fluorescence detection 总被引:4,自引:0,他引:4
Summary Sensitive detection of atmospheric formaldehyde and acetaldehyde can be achieved by use of silica-gel cartridges impregnated
with 2-diphenylacetyl-1,3-indandione-1-hydrazone (DAIH) to form fluorescent DAI hydrazones. The hydrazones are extracted with
acetonitrile and separated by reversed-phase HPLC with fluorimetric detection. The low detection limits achieved (0.25 ppb
CH2O or CH3CHO for sampling periods of 1 h) means that the sensitivity of the method is better than that of the classical dinitrophenylhydrazine
(DNPH) method. Several experimental conditions, such as collection and reaction efficiency, interference by ozone and storage
stability of blank and sampled cartridges have been investigated. There were no significant differences between ambient concentrations
of CH2O and CH3CHO measured concurrently with the DAIH and DNPH techniques (10–20% in the 0–5 ppb range). 相似文献
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An instrumentally simple and cost-effective method for the direct analysis of methyl bromide in ambient air is described. The method is based on the separation of sample components by gas chromatography, the conversion of methyl bromide to methyl iodide by reaction with an inorganic iodide salt, and the detection of the methyl iodide thereby produced by an electron-capture detector. Of the 20 different inorganic salts investigated here for conversion of methyl bromide to methyl iodide, zinc iodide was found to provide the greatest conversion efficiency. In addition, zinc iodide was found to provide high conversion efficiency at a modest reaction temperature, thereby minimizing both the thermal decomposition of compounds within the reaction volume and the level of column bleed introduced to the detector. The reactions of several other brominated and chlorinated organic compounds with zinc iodide have also been characterized. The successful application of this instrument to the quantitative determination of methyl bromide in a local background air sample is then demonstrated. 相似文献