Farias, Marcos E.Correa, N. MarianoSosa, LucasNiebylski, Ana M....
6页
查看更多>>摘要：Soybean is the most produced crop in Argentina, and 99 % corresponds to genetically modified soybean. One of the main produced varieties is Roundup Ready (R) soybean (RR), which was modified to express the enzyme CP4 5-enolpyruvylshikimate 3-phosphate synthase (CP4 EPSPS), which confers resistance to glyphosate, the main herbicide worldwide used. The possible impact of genetically modified organisms (GMO) has generated public concerns, thus increasing interest in the development of GMOs detection devices. In this work, an electrochemical immunosensor for CP4 EPSPS detection in soybean seeds was obtained, by using a gold electrode modified with an anti-CP4 EPSPS polyclonal antibody produced in our laboratory. The presented immunosensor resulted in a simple, low-cost, fast, and reproducible device. Also, labeling and/or signal amplification system was not necessary, since the sensor showed high sensibility with a low detection limit (lower at 0,038 % RR soybean, 38 ng mL(-1) CP4 EPSPS).
查看更多>>摘要：Nucleic acid extraction and purification before amplification is considered an essential step for nucleic acid amplification testing. However, this may cause losses or introduce errors that can lead to inaccurate results, especially when using samples with a small nucleic acid concentration. Here, we developed a direct digital chip that enabled us to detect nucleic acid without DNA extraction and purification. We have developed a self-priming liquid-dispensing digital PCR chip that does not require any external power. This is a robust anti-evaporation digital PCR chip with fast sampling and accurate quantification performance. Using this chip, we have estab-lished an on-chip direct nucleic acid amplification method that does not require nucleic acid extraction and purification for liquid biopsy samples. In order to verify the feasibility of this chip for clinical samples, we detected the EGFR T790M mutation from plasma. Results showed that EGFR T790M mutation could be detected with an accuracy of 100% and a sensitivity of 0.01%. Without nucleic acid extraction and purification, the assay avoids complex pre-processing, thus saving time and achieving precise quantification. We expect our direct digital PCR chip to have practical applications in diagnosis, screening, and research, especially in resource-deprived regions.
查看更多>>摘要：Antibiotic residues in aquatic environments have attracted wide attention. Considering the impacts on the ecosystem and human health, it is urgent to develop a rapid method for detecting antibiotic residues in the environment. In this work, a nanoscale lanthanide metal-organic framework Eu(TATB) with a stable red luminescence in aqueous solution is synthesized by the microemulsion method. Sulfamethazine (SMZ) is frequently most used in veterinary medicine as one of sulfonamides. Eu(TATB) can be used for sensitively and rapidly specific recognition of SMZ with low detection limit (0.67 mu M) and eminent recyclability. In addition, a paperbased visual system for point-of-care (POC) monitoring SMZ is devised by both using filter paper embedded with Eu(TATB) and our developed portable smartphone-involved imaging cassette. The naked eyes can observe that the red luminescence of the paper sensor gradually fades away at the presence of SMZ. This provides a reliable and effective method for on-site detection of sulfonamide antibiotics in the field of environmental monitoring.
查看更多>>摘要：Diazepam (DZP) was routinely prescribed to a large population troubled with anxiety disorders. However, due to the overuse and misuse, DZP and its chlorination disinfection byproduct 2-methylamino-5-chlorobenzophenone (MACB) caused environmental pollution and can be detected ubiquitously in drinking water in Beijing, China. However, little information is known about the metabolic dynamics of MACB. Here, we established desorption electrospray ionization mass spectrometry (DESI-MS) imaging method to visually and quantitatively assess the distribution and metabolism of MACB in zebrafish. The results showed that MACB specifically accumulated in spinal cord particularly in female zebrafish. Meanwhile, the accumulation of MACB could pass through the blood-brain barrier (BBB) and induced microglial phagocytosis of neurons. Therefore, the intervention strategies should be explored to restrict the release of such substances, eliminating the potential risks for both human beings and the eco-environment.
查看更多>>摘要：Cardiac troponin-I (CTnI) is one of the most popular biomarkers which can be utilized for the diagnosis and control of acute myocardial infarction in clinical practice. Here, a sandwich-type electrochemical immunosensor has been established using the zinc-based metal-organic framework/Fe3O4-COOH/thionine labeled anti-CTnI monoclonal antibody (Ab1-Zn-MOF/Fe3O4-COOH/Thi) nanocomposite as signaling molecule and a polymer film of cetyltrimethylammonium bromide (pCTAB) in the presence of choline chloride-urea deep eutectic solvent (DES) and anti-CTnI polyclonal antibody (Ab2) as immobilization substance of detecting surface. The porous ultrathin layers of Zn-MOF nanosheets successfully prepare a well-defined structure for Fe3O4-COOH electrocatalyst and Thi within a certain two dimensional (2D) regions, which enhances electrochemical reduction of Thi. The Ab1-Zn-MOF/Fe3O4-COOH/Thi nanocomposites were introduced to CTnI in the specimen and on the surface of pCTAB/DES-Au-SPE quantitative determination of CTnI was achieved using differential pulse voltammetry after sandwiching the CTnI target between Ab1-nanocomposite and Ab2 which was encapsulated into the pCTAB/DES-Au-SPE. This immunosensor indicated the appropriate assay performance for CTnI with the detection range of 0.04 ng mL-1 to 50 ng mL-1 and the limit of detection of 0.0009 ng mL-1. This study provides convenient plan for sensitive detection of bioanalytes and opens a path for the establishment of user-friendly and cost-effective device.
查看更多>>摘要：Matrix-assisted laser desorption/ionization mass spectrometry (MALDI-MS) has been widely applied in the analysis of phospholipids in biological samples. However, it remains a challenge to improve the sensitivity and reproducibility and to control the background noise of matrices. In this study, black phosphorus nanomaterial was used as the matrix of MALDI-MS, and microchannel technique was combined. This microchannel-integrated black phosphorus-assisted laser desorption/ionization (BPALDI) MS approach can effectively detect a variety of lipids with a small amount of sample, and has high sensitivity for phosphatidylcholines (PC) and lysophosphatidylcholines (LPC) with a detection limit of 0.2 mu g/mL. Compared with traditional matrices, BPALDI-MS has the advantages of high sensitivity, good reproducibility, and high salt tolerance. This method was successfully applied in the detection of serum PC/LPC ratios in children patients with asthma or bronchopneumonia. This work provides a novel application of black phosphorus matrix and microchannel technique, and gives new insights into method development of rapid screening and identification of disease indicators in biological fluids.
Trindade, Magno A. G.Goncalves, Daniel A.Carmo, Jessica S.Zanon, Layne Taynara S....
6页
查看更多>>摘要：The contamination of water sources by anthropogenic activities is a topic of growing interest in the scientific community. Therefore, robust analytical techniques for the determination and quantification of multiple substances are needed, which often require complex and time-consuming procedures. In this context, we describe a univariate calibration method to determine emerging multi-class contaminants in different water sources. The instrumental setup is composed of a lab-made glass electrochemical cell with three electrodes: Pt counter, Ag/ AgCl reference, and BDD working electrodes. With this system, we were able to simultaneously quantify tertbutylhydroquinone, acetaminophen, estrone, sulfamethoxazole, enrofloxacin, caffeine, and ibuprofen by differential pulse voltammetry. Only two calibration solutions are required for the Single-shot Dilution Differential Pulse Voltammetric Calibration (SSD-DP-VC) method described here, which can significantly improve sample throughput. Two robust univariate calibration strategies were also applied and compared with SSD-DP-VC. The new method is simple, fast, and comparable with traditional calibration methods, showing similar precision and accuracy for all determinations evaluated.
查看更多>>摘要：In the last decade, beta-lactams use in veterinary and human medicine increased to represent today about 15% of the overall consumption. Beta-lactams tend to degrade and metabolize in the environment. Therefore, analytical methods must be sensitive enough to quantify low concentrations of the parent molecules and also allow detection of metabolites. This study presents the development of a modified QuEChERS method for the extraction of seven beta-lactams and one degradation product (Amoxicillin, Ampicillin, Cefapirin, Cefoperazone, Cefquinome, Ceftiofur, Cloxacillin, and Amoxicillin-Diketopiperazine) from sewage treatment plant sludge and their analysis by liquid chromatography coupled with tandem mass spectrometry. Before the QuEChERS extraction, a dispersion step of the sample with EDTA-treated sand was optimized and added, allowing to facilitate the exchanges between the matrix and the extraction solvent. Then, to decrease the interferences present in the extract, a fast and efficient pass-through SPE was implemented. The optimized method was validated and showed satisfactory performances, in adequacy with the analysis of beta-lactams in solid environmental matrices. Limits of quantification lower than 20 ng.g(-1) for all analytes, high accuracy (96%-114% quantification on spiked samples nominal concentration) and interday precision (2%-12% RSD) were obtained. This method was then applied to eight sludge samples. Cefapirin and amoxicillin-diketopiperazine were detected in four samples each, at concentrations of 10.2-53.3 ng.g(-1) and 3.0-9.5 ng. g(-1) respectively. Thus, the developed method is very effective for the extraction of beta-lactams from environmental solid matrices.
查看更多>>摘要：Novel atmospheric pressure glow discharge (APGD) microplasma systems, sustained between a miniaturized flowing anode (FLA) or cathode (FLC) and a He jet, were investigated for the direct determination of Br and Cl, using optical emission spectrometry (OES). The impact of the most crucial operating parameters, i.e., the acid type and its concentration, the discharge current, the gas flow rate, and the sample flow rate, was studied for each of the proposed APGD-based systems. Under the optimized conditions, the analytical figures of merit were determined. The susceptibility to the matrix effects of both developed methods was verified as well. It was found that the mechanism of the analytes transport into the discharge likely relied on the cathode sputtering in the case of FLC-APGD and the formation of the volatile Br and Cl species for FLA-APGD. The DLs of Br and Cl were established to be relatively high, i.e., 0.15 and 1.5 mg L-1 for FLA-APGD and 2.1 and 18 mg L-1 for FLC-APGD. However, both studied methods turned out to be resistant to the presence of foreign ions in a sample, at relatively high concentrations. Hence, the proposed methods could be successfully applied for the determination of Br and Cl in water and juices samples and no major differences between the results obtained using the external standard calibration and the standard addition method were found.
Orduna-Diaz, AbduSalinas, Rafael A.Obregon-Hinostroza, OvierDominguez, Miguel A....
6页
查看更多>>摘要：The fabrication of biosensors has different future applications mainly from the perspective of eco-friendly technologies. Label-free strategies, recyclable materials and low-temperature processing are parameters to consider for the development of a new generation of biosensor devices. In this work, Zinc oxide (ZnO) Thin-film Transistors (TFTs) using recyclable plastic substrates were used for real-time enteropathogenic Escherichia coli detection as an approach for biosensing (bio-TFTs). Fourier Transform Infrared Spectroscopy was used to verify the characteristic absorption peaks at the different steps of the bio-TFT assembly process. The bio-TFTs are ready to observe the bacterial detection by electrical characterization. Finally, detection was validated by a coupled strategy that fuses the genomic DNA extraction from bacteria attached in situ over bio-TFTs surface and, the development of the Polymerase Chain Reaction to amplify specific genes from enteropathogenic Escherichia coli.
NSTL
Elsevier