查看更多>>摘要：? 2022 Elsevier B.V.pH homeostasis is essential for alkaliphiles, given their widespread use in biotechnological applications. However, quantitative monitoring of alkaline pH in alkaliphiles remains challenging. Here, we synthesized for the first time, a thermally activated delayed fluorescent (TADF) pH probe: NI-D-OH. Our probe exhibits a good linear relationship between fluorescence intensity and pH in the neutral to alkaline range (pH 7.0–8.6), as well as long-lived TADF emission. We further show that NI-D-OH can be used to monitor intracellular pH in living organisms, and evaluate the effect of Na+ on the pH homeostasis, demonstrating the potential for alkaline pH monitoring and time-resolved fluorescence imaging.
查看更多>>摘要：? 2022 Elsevier B.V.Recent advances in CRISPR/Cas biosensing have led to impressive performance in sensitivity, specificity, and speed for nucleic acid detection. However, the remarkable advantages (such as universality, ultralow, attomolar detection limits) of CRISPR/Cas biosensing systems are limited in testing non-nucleic acid targets. Herein, by synthesizing a functional hybrid conjugate of antibody and single strand DNA oligonucleotide, we had successfully demonstrated the capability to integrate CRISPR/Cas12a-based signal amplification into different types of immunoassay schemes without the need for any additional recognition molecule or molecular synthesis during the detection process, thus providing a simple but generally applicable approach to improve the conventional immunoassays with attomolar sensitivity for small protein detections, referred as the CRISPR-based Universal Immunoassay Signal Enhancer (CRUISE). CRUISE is capable of being integrated into various immunoassays either through the primary antibody or the secondary antibody, with sensitivity down to 1 fg mL?1 (～50 aM) and 6 logs of linear range for detecting cytokines, such as IFN-γ and EGFR, under 3–4 h. It has a 103 times higher sensitivity compared to a commercial IFN-γ ELISA kit, but uses the same experimental scheme. The same 1 fg mL?1 sensitivity along with 6 logs of linear range was realized for IFN-γ detection in human plasma samples. We are expecting that our CRUISE provides an alternative but simple, user-friendly and effective strategy for those who rely on the use of immunoassays, while struggling with the limits of their sensitivity or detection ranges.
查看更多>>摘要：? 2022 Elsevier B.V.The separation of boron in nuclear fuels by cloud point extraction (CPE) has been a challenge due to high acidity of digested sample solutions. High acidity hampers the coacervation of micelles. As a result, the cloud point temperature increases and thus could cause the inevitable loss of boron as volatile species. Herein we have proposed a novel CPE-assisted colorimetric method for the quantification of traces of boron (B) in uranium-based fuels. A 1:1 mixture of 2-ethyl hexane-1,3-diol (EHD) and curcumin dispersed in Triton X-114 surfactant was used in the proposed CPE process. We had investigated several compounds to act as micelle surface modifiers. Among them, only bromine water (Br2) was found not only to lower the cloud point temperature (CPT, from 80 °C to 42 ± 2 °C) but also resulted in the quantitative recovery of boron (≥95%). The CPE of boron from uranium matrix in a 2.0 mol L?1 HCl medium was suitable for direct chemical quality assurance of routine uranium-based fuels. The molar extinction coefficient of the boron-EHD-curcumin complex was found to be 4.75 × 105 L mol?1 cm?1 (λmax at 458 nm) in N,N-dimethyl formamide medium. The linear dynamic range and detection limit of the proposed analytical procedure were calculated to be 10–150 ng mL?1 and 0.8 ng mL?1 respectively. The proposed analytical methodology was validated by analysis of three in-house working reference materials of uranium. Determination of traces of boron in two uranium dioxide and two metallic uranium samples were found to demonstrate the applicability of the method. The relative standard deviation of the proposed method was found to be of 3–5%.
查看更多>>摘要：? 2022 Elsevier B.V.A data fusion approach for the rapid extraction of core scaffold information that can be used to facilitate structure determination for new psychoactive substance (NPS) tryptamines is described. The method involves the screening of DART-HRMS data of new tryptamines against a partial least squares-discriminant analysis (PLS-DA) model that predicts the core tryptamine structure class into which the compound can be grouped. The PLS-DA prediction model was created and trained using neutral loss spectra derived from collision-induced dissociation (CID) DART mass spectral analysis of 50 tryptamine structures acquired at 60 V and 90 V, in which the sample groups were revealed by hierarchical clustering analysis (HCA). HCA of the fused neutral loss data clustered the 50 tryptamines into 10 groups based on the identities of the neutral fragments lost during fragmentation. “Leave-one-structure-out” validation of the PLS-DA model gave 100% accuracy, precision, sensitivity, and specificity. For external validation, the ability of the model to classify four compounds that were unfamiliar to it was tested, and the model was found to correctly predict the skeletal framework in each case. The results show proof of concept for how this approach can aide in the identification of new emerging psychoactive compounds.
查看更多>>摘要：? 2022 Elsevier B.V.The rigorous and reasonable evaluation of uncertainty is crucial for the reliability of the results of a reference measurement procedure. A new uncertainty budget is proposed for uncertainty evaluation of a reference measurement procedure for total thyroxine in human serum based on isotope dilution liquid chromatography-mass spectrometry. In this work, a measurement model for uncertainty evaluation of triple isotope dilution-mass spectrometry was established. The propagation of uncertainties assigned to various input quantities was expressed in strict accordance with the measurement model. A detailed description of the uncertainty evaluation process for the measurement result of a specific serum is given, including the estimate of the input quantities and the determination of the combined standard uncertainty. The expanded uncertainty of the specific human serum (at coverage probability of 95%) was 4.8 nmol/L at the concentration level of 113.6 nmol/L.
查看更多>>摘要：? 2022 Elsevier B.V.SPR is a mature optical biosensor technology for detecting biomolecular interactions without fluorescence or enzyme labeling. In this paper, we acquire a sensitive SPR biosensor based on ZnO@Au nanomaterial, and the classical sandwich strategy using biotin-streptavidin for secondary signal amplification system was used to detect human IgG (hIgG). Nano-zinc oxide (ZnO) has the dual characteristics of nanocomposite and traditional zinc oxide, with large specific surface area and high chemical activity. Besides, the gold-coated ZnO nanocrystals improve the optical properties of ZnO and enlarge the loading capacity with better biocompatibility. Therefore, a sensing platform based on PDA-ZnO@Au nanomaterial was constructed on gold film modified with mercaptan. Meanwhile, the biotin-avidin system in SPR sensor field has been rapidly developed and applied. Due to the highly selection of streptavidin (SA) and biotin interact with each other, GNRs-SA-biotin-Ab2 (GSAB-Ab2) were constructed to obtain the secondary enhancement of SPR signal. The influences of experimental conditions were also discussed. With optimal experimental conditions, introducing GSAB-Ab2 conjugate combined with a sandwich format, the resulting SPR biosensor provides a favourable range for hIgG determination of 0.0375–40 μg mL?1. The minimum detection concentration of hIgG that can be obtained by this method is approximately 67-fold lower than the conventional SPR sensor based on gold film. The sensitivity of SPR biosensor is significantly improved in a certain range.
查看更多>>摘要：? 2022We developed a flexible laser scribed graphitic carbon based lactate biosensor fabricated using a low cost 450 nm laser. We demonstrated a facile fabrication method involving electrodeposition of platinum followed by two casting steps for modification with chitosan and lactate oxidase. The biosensor demonstrated chronoamperometric lactate detection within a linear range from 0.2 mM to 3 mM, (R2 > 0.99), with a limit of detection of 0.11 mM and a sensitivity of 35.8 μA/mM/cm2. The biosensor was successful in performing up to 10 consecutive measurements (one after the other) indicating good working stability (RSD <5%). Concerning storage stability, there was no decrease in signal response after 30 days of storage at 4 °C. Additionally, we demonstrate enzymatic lactate detection whilst the flexible polyimide substrates were fixed at a curvature (K) of 0.14 mm?1. No noticeable change in signal response was observed in comparison to calibrations obtained at a curvature of 0 mm?1, signifying potential opportunities for sensor attachment or integration with oral-care products such as mouth swabs. Both laser scribed graphitic carbon and Ag/AgCl modified-laser scribed graphitic carbon were successful as reference electrodes for chronoamperometric lactate measurements. Furthermore, using a three-electrode configuration on polyimide, lactate detection in both artificial saliva and sterile human serum samples was achieved for two spiked concentrations (0.5 mM and 1 mM).
查看更多>>摘要：? 2022 Elsevier B.V.In this paper, the precursor ZIF-8/NaCl composite material was successfully synthesized by the in-situ synthesis method, and the two-dimensional zinc doped carbon nanosheets (Zn CNs) were obtained after heat treatment of the precursor. Zn CNs were electrodeposited on carboxylated carbon nanotubes (MWCNTs-COOH) modified glass carbon electrode (GCE) to construct an electrochemical sensor for catechins. The materials are characterized using scanning electron microscope, X-ray photoelectron spectroscopy, and nitrogen adsorption-desorption isotherm. Zn CNs/MWCNTs-COOH composite provide the sensor with excellent electrochemical and electrocatalytic performance. Therefore, the sensor has a wide detection range (30.0–738 nM) and a low detection limit (LOD = 10.0 nM) for catechins. The effectiveness of the sensor was also verified in actual sample detection with good stability and accuracy. This study may provide a feasible solution for the detection of catechin.
查看更多>>摘要：? 2022 Elsevier B.V.A novel antibacterial quinolone was prepared with two chiral centers. For medicinal safety purposes, the four stereoisomers of the molecule are separated by HPLC using a Chiral (+)-Crownpack column (25 cm × 0.46 cm, 5.0 μm) with an eluent of 50 mM H2SO4. The values of the retention, separation, and resolution factors of RR-, SS-, RS-, and SR-stereoisomers were in the range of 1.15–7.55, 1.18 to 2.34, and 1.05 to 2.38 at 15, 20, 25, 30 and 35 °C temperatures. The values of the linearity, limits of detection, and limits of quantitation were in the range of 55.6–125, 1.5 to 4.0, and 14.0–37.6 μg mL?1. Chiral HPLC separation was validated properly. The thermodynamics parameters were in the range of 1.96–10.72 kJ mol?1 (ΔΔH), 0.013–0.041 kJ mol?1K?1 (ΔΔS) and ?0.52 to ?1.99 kJ mol?1K?1 (ΔG298). These values confirmed chiral separation as spontaneous and thermodynamically stable. The simulation study was used to understand the mechanism of the chiral separation at the supramolecular level. The binding affinities of the stereoisomers with the chiral stationary phase were in the range of ?3.0 to ?3.5 kcal mol?1. The hydrogen bonding was found responsible for the chiral separation. The reported HPLC conditions are inexpensive and may be used to separate the four stereoisomers successfully in any sample.
查看更多>>摘要：? 2022 Elsevier B.V.An electrochemical immunosensor for the accurate detection of cat neutrophil gelatinase-associated lipocalin (NGAL) in urine samples based on an electrode with a monolayer of gold nanoparticles (AuNPs) was proposed in this study. To fabricate the sensing electrode, a nickel mold with concave micron hemisphere array was prepared and then used to transfer the micron hemispherical structure onto a polyethylene terephthalate (PET) film using the hot embossing technique. A gold thin film was sputtered onto the micron hemispherical structure array, after which 1,6-hexanedithol and AuNPs were uniformly deposited on the PET membrane to form a sensing electrode. The NGAL concentrations were measured by electrochemical impedance spectroscopy after attaching the anti-NGAL. Results revealed that the proposed sensing scheme exhibited a wide dynamic detection range from 1 to 100 ng/mL, which is far enough to distinguish the healthy (NGAL concentration <10 ng/mL) from the damaged kidney. A low limit of detection and high sensitivity of 0.47 ng/mL and 10261.8 Ω ng?1mL, respectively, were also measured. After performing real sample detection using urine samples from cats collected at a veterinary hospital, the results confirmed that the proposed NGAL detection approach in this research could accurately detect the concentration of NGAL in cat urine samples.
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