查看更多>>摘要：Simple and accurate testing tools for SARS-CoV-2 viral RNA detection are essential for the prevention of the spread of the virus and timely governmental actions. Herein, we present a reverse transcription loop-mediated isothermal amplification (RT-LAMP) assay for the simultaneous detection of ORF1ab and N gene fragments of SARS-CoV-2 in one pot. Using two primer sets and two molecular beacon (MB) probes respectively labelled with different fluorophore, positive results were obtained with a limit of detection of 20 and 2 copies/mu L for ORF1ab and N gene fragments, respectively. Moreover, the RT-LAMP based assay was applied to detect single-site differences in S genes using two one-step displacement (OSD) probes targeting wild-type and mutant (P681R mutation was chosen as model) genes. Through that, the wild type strain and P681R mutant variant were well distinguished from each other, and a preliminary observation was also made on other mutations at this site such as P681H. The proposed method has high sensitivity for quantification and high specificity for mutation differentiation. In addition, it does not require accurate sophisticated thermal cycler instrumentation and can be used in clinical settings in resource-limited regions.
查看更多>>摘要：Accurate and automated determination methods for silicate and phosphate are in high demand to improve understanding of biogeochemistry and ecology in dynamic and complex estuarine-coastal ecosystems. Here, a portable automated analyzer is reported for the simultaneous determination of silicate and phosphate in water samples with varying salinity. After comprehensive optimization of the chemical reactions and flow manifold, the system demonstrated limits of detection of 0.09 and 0.05 mu mol L-1 for silicate and phosphate, respectively, exhibiting linearity at concentrations up to 400 and 200 mu mol L-1 with automated dilution, achieving relative standard deviations (n = 11) of 0.27% (20 mu mol L-1 silicate), 0.51% (5 mu mol L-1 phosphate) and 0.80% (1 mu mol L-1 phosphate). Compared with similar automated flow analyzers, the system exhibited advantages, such as low consumption of reagents (10-20 mu L/sample), portability (4.8 kg), rapid start-up (5 min), reliability (automated analysis of quality control sample) and applicability within a broad salinity range (from 0 to 35) allowing analysis of dynamic estuarine and seawater samples. The system was successfully applied to a routine monitoring program by a national marine station and is potentially suitable for installation on different observation platforms for on-line and real-time underway analysis of nutrients in coastal areas.
查看更多>>摘要：Rapid, highly sensitive, and high-throughput detection of biomarkers at low concentrations is invaluable for early diagnosis of various diseases. In many highly sensitive immunoassays, magnetic beads are used to capture fluorescently labeled target molecules. The target molecules are then quantified by detecting the fluorescent signal from individual beads, which is time consuming and requires a complicated and expensive detection system. Here, we demonstrate a high-throughput optical modulation biosensing (ht-OMB) system, which uses a small permanent magnet to aggregate the beads into a small detection volume and eliminates background noise by steering a laser beam in and out of the cluster of beads. Shortening the aggregation, acquisition, and well-to-well scanning transition times enables reading a 96-well plate within 10 min. Using the ht-OMB system to detect human Interleukin-8, we demonstrated a limit of detection of 0.14 ng/L and a 4-log dynamic range. Testing 94 RNA extracts from 36 confirmed RT-qPCR SARS-CoV-2-positive patients (C-t <= 40) and 58 confirmed RT-qPCR SARS-CoV-2-negative individuals resulted in 100% sensitivity and 100% specificity.
查看更多>>摘要：In this work, a brief electrochemical aptasensor was developed for highly sensitive detection of SARS-CoV-2 antigen utilizing an aptamer-binding induced multiple hairpin assembly strategy for signal amplification. In the presence of SARS-CoV-2, a pair of aptamers was brought in a close proximity according to the aptamerprotein antigen binding, which initiated strand displacement reaction thereby triggering a multiple hairpin assembly to obtain long linear DNA concatemers on the electrode surface. As the fabricated hairpin probes were labeled with biotin, massive streptavidin-alkaline phosphatases (ST-ALP) could be further introduced on the electrode interface via biotin-streptavidin interaction thus generating strong electrochemical signal in electrolyte solution containing 1-naphthol phosphate. Benefiting from the non-enzymatic multiple hairpin assembly signal amplification strategy, the designed aptasensor for SARS-CoV-2 spike protein detection exhibited the wide linear range from 50 fg.mL(-1 )to 50 ng.mL(-1 ) and low detection limit of 9.79 fg.mL(-1 ). Meaningfully, this proposed electrochemical assay provided a potential application for the point of care analysis of viral diseases under ambient temperature.
查看更多>>摘要：In clinical practice, sera creatinine level is regarded as a crucial biomarker for the diagnosis, staging and monitoring of kidney disease. An amperometric biosensor is rapid, accurate, and cost-effective, with a portability and a simple operation. Herein, we report for the firsttime a disposable, printed amperometric biosensor for the clinical evaluation of creatinine in renal function detection. The sensor is constructed based on Prussian blue/ carbon-graphite paste as the working electrode and the immobilization of creatinine amidohydrolase, creatine amidinohydrolase and sarcosine oxidase. The creatinine biosensor shows a linear detection range from 0.05 to 1.4 mM with a detection time of about 3 min. In addition, the sensor shows a high stability that can maintain above 86% of the initial activity after being stored for over 4 months. Moreover, the sensor shows almost the same results as those with the Jaffe method for measuring the real blood samples. We anticipate that the creatinine biosensor could be widely used in the medical and healthcare areas, especially for at-home testing and onsite medical examinations.
查看更多>>摘要：A new oxime compound, 4-(benzimidazolisonitrosoacetyl)biphenyl (BIBP) was synthesized and used as a complexing agent in this study to preconcentrate trace amounts of Pb(II) ions with vortex-assisted restricted access based supramolecular solvent microextraction (RA/SUPRAS-LPME) method. The new complexing agent was characterized by a combination of elemental analyses, Proton Nuclear Magnetic Resonance (H-1-NMR), Carbon 13 Nuclear Magnetic Resonance (C-13 NMR) and Fourier Transform Infrared spectroscopy (FT-IR) and techniques. Extraction of the complex which was formed at pH 8.0 was done by using a supramolecular solvent phase of tetrahydrofuran (THF) and 1-decanol. A microsampling flame atomic absorption spectrophotometer was used to measure the lead ion concentrations of the extract. The method optimized and the optimum experimental conditions were found as; pH = 8, amount of the ligand 2,25 mg, supramolecular solvent volume 50 mu L, sample volume 20 mL and vortex time 3 min. The limit of detection (LOD), limit of quantification (LOQ) were calculated as 0.69 mu g L-1 and 2.29 mu g L-1, respectively. Linear range was found between 15.1 mu g L-1 and 606 mu g L-1. The developed method was applied to Pb(II) determination in real samples after evaluating the accuracy by using the TMDA-53.3 fortified environmental water sample as certified reference material.
查看更多>>摘要：Sorbitol is known as a biomarker for the evaluation of the progress of diabetic complications. We have developed a sorbitol biosensor using an optical fiber for rapid diagnosis and pathological evaluation of diabetic complications. In this paper, we measured blood sorbitol in diabetic rats using an improved biosensor, and discussed the effectiveness of the developed biosensor and the significance of sorbitol measurement. In order to investigate the effectiveness of the developed biosensor, the blood sorbitol level of type II diabetic rats prepared by streptozotocin administration was measured with the developed sensor. The values of sorbitol were highly correlated with the values measured by the F-kit of food analysis and that we confirmed the sorbitol concentration could be quantified using the developed biosensor. Furthermore, the aldose reductase inhibitor "eparlrestat", which is a therapeutic drug that suppresses the accumulation of sorbitol, was administered to diabetic rats, and the blood sorbitol level was measured with the developed biosensor. As a result, the blood glucose level was high in both the treated group and the non-treated group, but the blood sorbitol level in the treated group decreased. The results suggest that the measurement of the sorbitol level with the developed biosensor in addition to the blood glucose level enables evaluation of complications like diabetic neuropathy. In the future, we expected that the developed sorbitol biosensor will be miniaturized, the pretreatment method for blood samples will be simplified, and it will be applied to the development of therapeutic agents for diabetic complications and personalized medicine.
查看更多>>摘要：There is an urgent need to develop fast and sensitive detection methods for foodborne pathogens. But the conventional culture method that typically requires 2-3 days is not ideal for the rapid analysis. Food samples demonstrate a great challenge for direct detection due to the complex matrix. Hence, we present a new method based on the phage long-tail-fiber proteins (LTF4-a) immobilized magnetic nanoparticles (MNPs) for specific separation and concentration of Salmonella. The LTF4-a-MNP was prepared via the coupling of recombinant LTF4-a with MNPs and used to isolate and enrich Salmonella cells from contaminated food samples. The captured material was further integrated with the direct PCR program for accurate detection of Salmonella. Our study successfully established a new method for detecting contaminated food samples of Salmonella, the overall approach took no more than 3 h, which allowed a detection limit of 7 CFU/mL, demonstrating a promising alternative to the immunomagnetic separation method by replacing antibodies or aptamers, that is compatible with downstream analysis.
查看更多>>摘要：A new method that simultaneously alters multicolor upconversion luminescence (UCL) and improves overall UCL intensity, predominantly in red-emission bands, is presented here. Remarkedly enhanced temperature sensitivity at ultralow temperatures was also observed in Yb/Cu co-doped NaErF4 through transition metal Cu2+-doping. Varying the dopant (Cu2+) concentration in NaErF4:Yb effectively controlled the structure, allowing for blue, green, and red UCL output. Large enhancement across the entire UCL spectrum was observed for Cu2+-doped upconversion nanoparticles (UCNPs) compared to UCNPs not doped with Cu2+, resulting from non-radiative energy transfer between Cu2+ and Er3+. The rapid response of the NaErF4:Yb/Cu complex allowed for bioimaging of heart tissue within 1 h. Moreover, the relative sensitivity of UCNPs increased from 0.91% K-1 to 1.48% K-1 with metal Cu2+ doping at an ultralow temperature, which significantly impacts biomarker dependence on UCNPs.
Solihat, Nissa NurfajrinSon, SeungwooWilliams, Elizabeth K.Plante, Alain F....
8页
查看更多>>摘要：This study assessed the applicability of artificial neural networks (ANNs) as a tool to identify compounds contributing to compositional differences in coal-contaminated soils. An artificial neural network model was constructed from laser desorption ionization ultrahigh-resolution mass spectra obtained from coal contaminated soils. A good correlation (R-2 = 1.00 for model and R-2 = 0.99 for test) was observed between the measured and predicted values, thus validating the constructed model. To identify chemicals contributing to the coal contents of the soils, the weight values of the constructed model were evaluated. Condensed hydrocarbon and low oxygen containing compounds were found to have larger weight values and hence they were the main contributors to the coal contents of soils. In contrast, compounds identified as lignin did not contribute to the coal contents of soils. These findings were consistent with the conventional knowledge on coal and results from the conventional partial least square method. Therefore, we concluded that the weight interpretation following ANN analysis presented herein can be used to identify compounds that contribute to the compositional differences of natural organic matter (NOM) samples.
NSTL
Elsevier