查看更多>>摘要：? 2022 Elsevier B.V.Here, based on the design of rational primers and copper nanoclusters (CuNCs), we present a method for the accurate detection of the SARS-CoV-2 Delta variant, which is capable of distinguishing the Delta variant with its single nucleotide polymorphism from the ‘wild type’ coronavirus (NC_045512.2), and realizing visualization signal out. Speci?cally, we show that dual priming oligonucleotide (DPO) primers and AT primers can be used to distinguish between wild types and mutations of this virus by polymerase chain reaction (PCR) analysis and that visualization can be achieved via the red fluorescence of CuNCs in ultraviolet radiation. Among the results, it was found that the R-1-down (DPO)-6I and F-1-30 AT, with the single nucleotide deletion site designed at the 3′ end of the downstream primer, showed the best specificity towards the Delta variant. Moreover, the use of AT primers increased the AT contents of the PCR products, thus meeting the template requirements generated by the CuNCs. It was also found that the AT primers could assist with improving detection specificity. Finally, we demonstrate that the visualization of the CuNCs-based detection assay exhibited a linear relationship in 0.5 pg μL?1–50 ng μL?1, with a limit of quantitation (LOQ) of 0.5 pg μL?1.
查看更多>>摘要：? 2021Recent advances in microelectronics and electrochemical sensing platforms have preceded the development of devices for personal monitoring and managing physiological and metabolic information that exploit sweat as a noninvasive, convenient approach for providing information about underlying health conditions, such as glucose level monitoring. Although most sweat glucose sensors have targeted applications during exercise and other active stimulation induced-sweat, natural sweating offers an attractive alternative with minimal effect on users that can be accessed during routine and sedentary activities without impeding personal lifestyle and preserves the correlation between blood and sweat glucose. Here, we present a noninvasive sweat glucose sensor with convenient hydrogel patches for rapid sampling of natural perspiration without external activities that stimulate sweating. The wearable hydrogel patch rapidly takes up natural sweat from the hand and serves as a medium for electrochemical sensing. A prussian blue-doped poly(3,4-ethylenedioxythiophene nanocomposite (PB-PEDOT NC) electrode provides cost-effective, stable and excellent electrocatalytic activity in sweat glucose measurements. We demonstrated sweat glucose sensor functionality by long-term measurements of glucose in sweat from human subjects consuming food and drinks. By enabling the analysis of sweat glucose during routine and sedentary activities, the sweat glucose sensor shows great promise for clinical-grade glucose management and enlarges the scope of next-generation noninvasive sensing systems.
查看更多>>摘要：? 2022 Elsevier B.V.The proliferation of harmful cyanobacterial algal blooms is of concern due to the associated release of toxins affecting ecosystems and human health. The paralytic shellfish poison saxitoxin (STX) is a small polar alkaloid that can occur in inland and marine aquatic environments. Here, we optimized a fast and sensitive analytical method for the determination of STX, neosaxitoxin (NeoSTX), and their decarbamoyl analogues in surface waters. The method involves a simple filtration, addition of isotope-labelled internal standard (ILIS), and analysis by on-line solid-phase extraction coupled to hydrophilic interaction liquid chromatography high-resolution mass spectrometry (on-line SPE–HILIC-HRMS). Except glass fiber filters, other tested materials (e.g., nylon, nitrocellulose) provided suitable filtration performance. Time-dependent adsorptive losses occurred during the LC-MS batch sequence if glass autosampler vials were used, while no such effect was observed for polypropylene autosampler vials. Matrix effects were evaluated for 4 different quantification scenarios, including external vs. internal curves and neat reagent water vs. matrix-matched curves. Matrix-matched calibration with ILIS correction (NeoSTX-15N7) provided the best performance overall. The analytical method was validated in freshwater lake water and estuarine brackish water (30‰ salinity), with suitable determination coefficients (R2 > 0.9975), matrix spike accuracy (90–107%), and intraday/interday precision (RSD of 0.61–16%). Method limits of detection (LOD in lake water: 0.72–3.9 ng/L) are also improved over most of the recent literature. The method was applied to a set of 302 surface water samples collected in Canada, France, and the United Kingdom, and positive detections were reported for STX (max: 98 ng/L), decarbamoyl-STX (max: 15 ng/L), and NeoSTX (max: 87 ng/L).
查看更多>>摘要：? 2022 Elsevier B.V.Spinal cord injury is one of the most devastating complications of spinal surgery, often resulting in numbness, pain or paralysis. Minor injuries in the spinal cord are hard to be identified and existing imaging modalities are unable to provide intraoperative monitoring. Monitoring pathological change at the site of injury is a key factor in staging and treatment decision making as well as prognosis of spinal cord injury. Herein, we offer the fluorescence imaging with intraoperative visualization and detection accuracy for bioimaging to resolve the problem. A novel red fluophore AuNDs caped with glutathione is prepared, which exhibits some advantages such as ultra-small size, negligible biotoxicity, superior water solubility and great biocompatibility. AuNDs fluorophore especially exhibit both of a remarkable photoluminescence stability and high attenuation coefficient to X-rays. In addition, AuNDs can be used as CT contrast agent for spinal cord, which avoid the high toxicity and weak CT signal of traditional iodine contrast. After intradural injection into the spinal cord, AuNDs are transported through the flow of cerebrospinal fluid and bound to the spinal cord parenchyma. not only the bioimage of the entire spinal cord can be achieved as quick as 15 min, but they are also particularly beneficial to long-term imaging of complex physiological environments in vivo, with negligible quenching. Comparing from the bright red fluorescence in adjacent normal spinal cord sites, there is almost no fluorescence in spinal cord at the areas of the injury. We suggest that AuNDs are unable to enter the injury sites of necrosis and ischemia, which promote a different contrast imaging from the normal one. The bright red fluorescence of the AuNDs significantly overcome the restriction of the blue autofluorescence of the biological tissues, providing a clear boundary for observation of the thin spinal cord injury. As a result, we developed the AuNDs with fluorescent and CT dual-mode bioimaging capability to clearly and effectively diagnose spinal cord injury, which are expected to provide a novel visualization imaging regent for clinical use.
查看更多>>摘要：? 2022Cocaine is one of the mainly used illegal drugs in the world. Using the signal amplification elements of terminal deoxynucleotidyl transferase (TdT) and CRISPR-Cas12a, a highly sensitive and simple electrochemical aptasensor was introduced for cocaine quantification. When, no cocaine existed in the sample, the 3′-end of complementary strand of aptamer (CS) was extended by TdT, leading to the activation of CRISPR-Cas12a and remaining of very short oligonucleotides on the working electrode. So, the current signal was remarkably promoted. With the presence of cocaine, CS left the electrode surface. Thus, nothing changed following the incubation of TdT and CRISPR-Cas12a and the Aptamer/Cocaine complex presented on the electrode. Consequently, the [Fe(CN)6]3-/4- could not freely reach the electrode surface and the signal response was weak. Under optimal situations, the biosensor revealed a wide linear relation from 40 pM to 150 nM with detection limit of 15 pM for cocaine. The sensitivity of the analytical system was comparable and even better than other reported methods for cocaine detection. The designed method displayed excellent cocaine selectivity. The aptasensor could work well for cocaine assay in serum samples. So, the aptasensor is expected to be an efficient analytical method with broad applications in the determination of diverse analytes.
查看更多>>摘要：? 2022 Elsevier B.V.Despite their very wide use in various fields, knowledge concerning surfactants in environmental solid matrices is generally poor. One of the difficulties encountered in the analysis of surfactants is their very diverse physicochemical properties which require different extraction techniques. The objective of this work was therefore to develop an extraction method in sediments that allows the simultaneous analysis of anionic, cationic and non-ionic surfactants. Different extraction techniques (salting-out, ultrasound), solvents and additives were compared. The optimized method, followed by analysis by coupling liquid chromatography with tandem mass spectrometry, was then validated and applied to real samples in which the analytes were quantified by matrix matched calibration. Optimization of the extraction parameters showed different trends depending on the surfactant family. However, ultrasound assisted extraction with a 90/10 acetonitrile/water mixture at 1% acetic acid and 0.1 M EDTA showed the best results overall. The quantification limits obtained, between 6.4 μg/kg for linear alkylbenzene sulfonate (LAS) C10 and 158 μg/kg for 1-laureth sulfate, allow the analysis of traces in sediments. Eighteen of the 27 targeted surfactants were thus detected. The highest concentrations were found for LAS and quaternary ammoniums. Strong correlations between concentrations of different homologues of the same families of surfactants were observed.
查看更多>>摘要：? 2022 Elsevier B.V.This work explores the capability of antithrombin III-functionalized capillary monolithic columns (in-line coupled with MS detection) to selectively capture, release and detect high affinity binders of antithrombin III (AT III) from oligosaccharides mixtures. The in-situ characterization of home-made AT III affinity columns was done by frontal affinity chromatography coupled to MS detection using fondaparinux as model ligand. Three different preparation methods of miniaturized antithrombin III monolithic affinity columns were optimized and compared. Immobilization of antithrombin III onto Concanavalin A functionalized column is the simplest method but leads to lowest protein density. The two other methods, direct grafting on aldehyde preactivated monoliths and immobilization of biotinylated antithrombin III to streptavidin-functionalized columns, require the presence of fondaparinux to protect the heparin binding site during the grafting process. Up to 1.3 ± 0.3 pmol cm?1 of antithrombin III were immobilized with both methods. The direct coupling of such miniaturized affinity columns to MS-detection was made possible by optimization of the elution step. Ammonia (0.1 M) was chosen as an efficient and MS compatible solvent to elute fondaparinux. Finally, the complete analytical workflow (capture/elution/detection) was demonstrated to allow the selective capture and elution of fondaparinux initially contained in a complex oligosaccharide mixture with a limit of detection of 1 pmol.
查看更多>>摘要：? 2022 Elsevier B.V.A label-free electrochemical immunosensor was constructed for cancer antigen 125 (CA125) detection based on multiple-enlargement means of layer-by-layer (LBL) assembly of ordered mesoporous carbon (CMK-3), gold nanoparticles (Au NPs) and MgAl layered double hydroxides containing ferrocenecarboxylic acid (Fc@MgAl-LDH). A CMK-3(Au/Fc@MgAl-LDH)n multilaminate nanocomposites was designed using technology of LBL self-assembly among negatively charged Au NPs, positively charged CMK-3 and Fc@MgAl-LDH nanosheets. The CMK-3(Au/Fc@MgAl-LDH)n multilaminate nanocomposites was used as carriers to increase the immobilization of antibody and the number of loading Fc, conductors to strengthen conductivity and enhancers to amplify signal of Fc step-by-step. Besides, this special and excellent way of LBL assembly can immensely amplify the signal of immunosensor and more immobilize the biomolecules, and label-free method is a more simple the measuring way and the procedure. The immunosensor displayed a wider linear range of 0.01 U ml?1–1000 U ml?1 and a lower detection limit of 0.004 U ml?1. Therefore, the sensor can stablely and accurately be applied for CA125 detection in clinical cancer diagnosis.
查看更多>>摘要：? 2022Detection of ultralow concentration of tetracycline (TC) plays a key role in food safety and human health. Herein, we fabricated an enzyme-free dual-amplification assay for sensitive detection of TC in milk. The sensing system ingeniously combined Mg2+-dependent DNAzyme (MNAzyme) cleavage and catalytic hairpin assembly (CHA). Through the binding of TC and specific aptamer (Apt), DNA1 was released from the Apt-DNA1 complex. Then the separated DNA1 would hybridize with DNA2 to activate the catalytic activity of MNAzyme, which subsequently cleaved the substrate H0 and generated a new unit to trigger the following CHA reaction between H1 and H2, thereby releasing the G-rich sequence of H1 to induce the formation of G-quadruplex–hemin DNAzyme as a colorimetric signal readout. Under optimal conditions, the absorption intensity exhibited a significant linear correlation with the logarithm of the target TC concentration over a range of 4 orders of magnitude dynamic range from 1 pM to 10 nM. The limit of detection was calculated to be 0.89 pM and the method showed high selectivity for TC. More impressively, the proposed method was employed for TC determination in the milk sample.
查看更多>>摘要：? 2022 Elsevier B.V.An ultrasensitive electrochemical detection of the activity and inhibition of T4 polynucleotide kinase (T4 PNK) was developed by using magnetic Fe3O4@TiO2 core-shell nanoparticles, which was triggered by a rolling circle amplification strategy (Fe3O4@TiO2-RCA). We used Fe3O4@TiO2 as a substrate to anchor a DNA primer. DNA S1 with 5′-OH termini was phosphorylated in the presence of T4 PNK and ATP, which was adsorbed on the surface of Fe3O4@TiO2 NPs and served as the primer for subsequent RCA reactions. After adding circular template DNA S2, RCA was initiated in the presence of phi29 DNA polymerase and dNTPs. Then, Fc-labeled DNA S3 (Fc-S3) was hybridized with RCA. The obtained Fe3O4@TiO2-RCA was adsorbed on the surface of a magnetic gold electrode (MGE) by magnetic enrichment, resulting in an enhanced electrochemical signal. The T4 PNK activity can be monitored by measuring the electrochemical signal generated. This electrochemical assay is sensitive to the activity of T4 PNK with a dynamic linear range of 0.00001–20 U/mL and a low detection limit of 3.0 × 10?6 U/mL. The proposed strategy can be used to screen the T4 PNK inhibitors, so it has great potential in the discovery of nucleotide kinase-target drug and early clinical diagnosis of cancer.
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