查看更多>>摘要：Ultra-sensitive detection of 2,4,6-trinitrotoluene (TNT) plays an important role in society security and human health. The Raman probe molecule p-aminothiophenol (PATP) can interact with TNT in three ways to form a TNT-PATP complex. In this paper, a 'sandwich' structure was developed to detect TNT with high sensitivity. Au nano-pillar arrays (AuNPAs) substrates modified by low-concentration PATP through Au-S bonds were acted as capture probe for TNT. Meanwhile, Ag nano-particles (AgNPs) modified by PATP at higher concentration were employed as tags for surface-enhanced Raman scattering (SERS). The formation of the TNT-PATP complex is not only the means by which AuNPAs substrates recognize and capture TNT, but also links the SERS tags to TNT, forming an AuNPAs-TNT-AgNPs 'sandwich' structure. The Raman signal of PATP was greatly enhanced mainly because novel 'hot spots' formed between the AuNPAs and AgNPs of the 'sandwich' structure. The Raman signal of PATP was further amplified by the chemical enhancement effect induced by the TNT-PATP complex formation. Based on this mechanism, the limit of detection (LOD) of TNT was determined from the Raman signal of PATP. The LOD reached 10(-9) mg/mL (4.4 x 10(-12) M), much lower than that suggested by the US Environmental Protection Agency (88 nM). Moreover, TNT was selectively detected over several TNT analogues 2,4-dinitrotoluene (DNT), p-nitrotoluene (NT) and hexogen (RDX). Finally, the 'sandwich' structure was successfully applied to TNT detection in environmental water and sand.
Hassanain, Waleed A.Theiss, Frederick L.Izake, Emad L.
7页
查看更多>>摘要：We present a sensitive label-free surface enhanced Raman spectroscopy (SERS) method for the discrimination between the recombinant and endogenous human Erythropoietin (EPO) isoforms. The proposed methodology comprises a lectin-functionalised extractor chip for the extraction of the recombinant human EPO (rhuEPO) and the endogenous EPO (enEPO) from blood plasma. The disulfide bond molecular structure of the purified isoforms was modified to chemisorb the biomolecules onto a SERS substrate in a unified orientation, thus maximizing the reproducibility and sensitivity of the SERS measurements. The acquired SERS spectra of the EPO isoforms showed diagnostic Raman bands that allowed for the discrimination between rhuEPO and enEPO. The method was also used for the SERS quantification of rhuEPO and enEPO down to 0.1 pM and 0.5 pM, respectively. The SERS determination of the protein isoforms was cross validated against ELISA. The new SERS method has strong potential for the rapid screening of rhuEPO doping in athletes and for the therapeutic drug monitoring of rhuEPO treatment in cancer patients.
查看更多>>摘要：Enrofloxacin (ENR) is a broad-spectrum fungicide that has been largely applied in pharmacy and animal-specific medicine. In this paper, a simple, novel and highly sensitive molecularly imprinted electrochemiluminescence (MIP-ECL) sensor based on mercaptopropionic acid-functionalized copper nanoclusters (MPA-Cu NCs) was developed to selectively detect enrofloxacin (ENR). MPA-Cu NCs prepared by a one-step method were used to modify the glassy carbon electrode. A molecularly imprinted polymer film containing the cavity was constructed after electropolymerization and elution. Under optimized conditions, the MIP-ECL sensor could detect ENR in the range of 0.1 nM(-1) mu M (R-2 = 0.9863) with a low limit of detection of 27 pM, and the recovery rates of ENR in biological and lake water samples were 88.20-105.0%. The MIP-ECL sensor provided path to improve the stability issues of Cu NCs, which might open promising avenues to develop new ECL systems for biological analysis and environmental water monitoring.
查看更多>>摘要：Glucagon-like peptide (GLP)-1 and the glucose-dependent insulinotropic peptide (GIP) are incretin hormones that regulate the nutrient-stimulated insulin secretion from pancreatic 13-cells. Their low plasma concentrations and rapid clearance pose certain methodological challenges for their detection and quantification. The currently available immunomediated techniques to monitor these hormones overestimate, to some extent, their actual concentration. Hence, the present study is aimed at developing a robust and reliable methodology for the identification and quantification of active and inactive forms of the incretins GLP-1 and GIP, in human plasma, by UHPLC-ESI-QqQ-MS/MS. A comparative study of different SPE cartridges was carried out, being identified OASIS HLB as the most efficient one, with recoveries up to 80%. The method provides adequate linearity, from 4.88 to 1250 nM, and low intervals of LOD and LOQ for each analyte (ranges from 0.01 to 3.42 nM and from 0.10 to 34.17 nM, respectively). The methodology described was validated upon a clinical trial with overweight subjects (n = 20) (ClinicalTrials.gov NCT 04016337), showing the capacity of the newly developed methodology to detect the augment of the plasma concentration of both GLP-1(7-36) and GLP-1(9-36) between 30 and 60 min after the consumption of a sucrose sweetened fruit-based beverage, while the plasma concentration of GIP remained in levels lower than the LOQ. The proposed methodology provides further insights into the mechanisms of action of bioactive compounds and food components in the frame of the glycemic control and would contribute to the assessment of the efficacy of antidiabetic drugs.
查看更多>>摘要：Cryptococcal meningitis (CM) is a global threat with significant attributable morbidity and mortality. Information on microfluidic detection for CM diagnosis is still limited. We developed a multifunctional microfluidic module that integrated the pathogen enrichment and on-chip nucleic acid extraction. The module adopted a simple filtration membrane to effectively capture Cryptococcus cells and simplify the process, and combined lyticase digestion, alkaline lysis and heating methods to optimize the strategy to achieve nucleic acid extraction. The entire process was operated in the module, which reduced the exposure risk of directly processing cryptococcal samples. A portable one-pot lyophilized LAMP reagent bead with no temperature limit was developed, which improved the flexibility of operation. This module did not require any additional instrument, and is promising to develop a simple, rapid, and efficient approach to realize the "sample in and answer out" detection of real CSF samples. This microfluidic module had practical prospects and is expected to replace LFA for efficacy evaluation and follow-up in the middle and late stages of CM treatment, and could be used as an auxiliary method to confirm cases with questionable LFA results in the early diagnosis of CM.
查看更多>>摘要：Rheumatoid arthritis (RA), an autoimmune and chronic inflammatory disorder, is an incurable disease. We developed a peptide-based electrochemical sensor using electrochemical impedance spectroscopy that can be used to detect autoantibodies for RA diagnostics. We first validated that the developed peptide showed high sensitivity and could compliment the current gold standard method of an anti-cyclic citrullinated peptide antibody (anti-CCP) ELISA. The developed peptide can be modified on the nanogold surface of the working electrode of sensing chips through the method of a self-assembling monolayer. The sensing process was first optimized using a positive control cohort and a healthy control cohort. Subsequently, 10 clinically confirmed samples from RA patients and five healthy control samples were used to find the threshold value of the impedance between RA and healthy subjects. Furthermore, 10 clinically confirmed samples but with low values of anti-CCP autoantibodies were used to evaluate the sensitivity of the present method compared to the conventional method. The proposed method showed better sensitivity than the current conventional anti-CCP ELISA method.
查看更多>>摘要：Phenolic compounds are an interesting class of natural products because of their proposed contribution to health benefits of foods and beverages and as a bio-source of organic (aromatic) building blocks. Phenolic extracts from natural products are often highly complex and contain compounds covering a broad range in molecular properties. While many 1D-LC and mass spectrometric approaches have been proposed for the analysis of phenolics, this complexity inevitably leads to challenging identification and purification. New insights into the composition of phenolic extracts can be obtained through online comprehensive two-dimensional liquid chromatography (LC x LC) coupled to photodiode array and mass spectrometric detection. However, several practical hurdles must be overcome to achieve high peak capacities and to obtain robust methods with this technique. In many LC x LC configurations, refocusing of analytes at the head of the 2D column is hindered by the high eluotropic strength of the solvent transferred from the 1D to the 2D, leading to peak breakthrough or broadening. LC x LC combinations whereby a purely aqueous mobile phase is used in the 1D and RPLC is used in the 2D are unaffected by these phenomena, leading to more robust methods. In this contribution, the combination of temperature-responsive liquid chromatography (TRLC) with RPLC is used for the first time for the analysis of phenolic extracts of natural origin to illustrate the potential of this alternative combination for natural product analyses. The possibilities of the combination are investigated through analysis of wine extracts by TRLC x RPLC-DAD and TRLC x RPLCESI-MS.
查看更多>>摘要：A novel label-free and enzyme-free detection strategy has been developed for the electrochemical biosensor detection of isocarbophos (ICP) using UiO-66-NH2 and aptamer as the signal transducers. In this work, the ICP aptamers were attached to UiO-66-NH2 through physical mixing and chemical combination methods. In the presence of ICP, the aptamers could undergo conformational change and bind to them, which prevent the electron transfer to the surface of electrode. By comparing the two conjunction approaches of aptasensors, these proposed strategies could selectively and sensitively detect ICP with a detection limit of 6 ng mL(-1) (20.74 nM) and 0.9 ng mL(-1) (3.11 nM). Furthermore, we have also demonstrated the capability of this strategy in the detection of ICP in real samples from vegetable and fruit extract, indicating the potential application of this strategy in food safety issues.
查看更多>>摘要：Bimetallic nanoparticles (NPs), including core-shell structure and bimetallic alloy nanoparticles, were synthesized and characterized using flow field-flow fractionation (FlFFF), single particle inductively coupled plasma mass spectrometry (SP-ICP-MS), and transmission electron microscope (TEM) with energy-dispersive x-ray spectroscopy (EDS). For the core-shell particles, a nominal 80 nm commercial core-shell AuAg bimetallic nanoparticle was used to examine the applicability of SP-ICP-MS to determine the core size of Au and shell thickness of Ag. Then, the method was applied to estimate the core size of Au and shell thickness of Ag for the laboratory synthesized particles. The results were compared with those obtained from TEM-EDS. For the alloy nanoparticles, two synthesis protocols, based on the galvanic replacement of Ag seed particles with Au, were used. One was to prepare a hollow AgAu particle by varying the volume of dissolved Au in basic solution (K-gold) to etch some parts of AgNPs to dissolved ionic silver with the formation of AuNPs covering the remaining AgNPs, producing a hole inside the core nanoparticles. Another protocol was to prepare AgAu alloy nanoparticles. SPICP-MS was used in combination with FlFFF to provide information on the changes of particle size with varying volume of K-gold reagent. Hydrodynamic diameter increased with increasing K-gold, as observed by FlFFF. With SP-ICP-MS without prior FlFFF, bimodal distributions were observed in the size distribution of Au and Ag. With prior FlFFF, monomodal distributions were observed by SP-ICP-MS, which allow the use of particle concentration and size to estimate the mass concentration of elements on the fractionated bimetallic nanoparticles. This study illustrates the potential use of SP-ICP-MS for gaining information about particle transformation during the synthesis of bimetallic nanoparticles.
查看更多>>摘要：A molecularly imprinted biosensor for lysozyme based on the polymer nanoparticles self-assembled from watersoluble and electroactive poly (gamma-glutamic acid) modified with 3-aminothiophene copolymer were prepared. The water-soluble copolymer made imprinting of lysozyme in aqueous solution possible and thus facilitated improvement of the activity of LYS. Subsequent electro-polymerization not only locked the recognition site between copolymer and lysozyme but also created a conductive polymer network, which can enhance the electron transfer rate and increase the conductivity of the film. The prepared molecularly imprinted biosensor exhibited a wide linear range from 1 x 10-10 to 1 x 10-5 mg mL-1, and satisfactory selectivity, stability, repeatability for lysozyme detection.
NSTL
Elsevier