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Pergamon Press
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Pergamon Press

0039-9140

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    Colorimetric ELISA based on urease catalysis curcumin as a ratiometric indicator for the sensitive determination of aflatoxin B1 in grain products

    Dai H.Huang Z.Liu X.Bi J....
    5页
    查看更多>>摘要：? 2022There is an urgent need to measure aflatoxin B1 (AFB1) in food to prevent contaminated food consumption. In this work, a novel colorimetric enzyme-linked immunosorbent assay (ELISA) was developed for the detection of AFB1 using curcumin as a colorimetric indicator. An indirect competitive enzyme-label immunoassay was developed using urease and rabbit anti-mouse immunoglobulin G labeled with gold nanoparticles as the signal-transduction tag. Urease catalyzed the hydrolysis of urea to produce ammonia, which increased the pH of the solution. The phenolic hydroxyl group of curcumin ionized into phenolic oxygen anions under alkaline conditions, which strengthened the synergistic effect of electron supply and absorption in curcumin. As a result, the color of curcumin changed from yellow to reddish-brown, producing a visible color change. Under optimal conditions, AFB1 could be qualitatively determined with the naked eye, and quantitatively assessed by measuring the ratio of absorbance at wavelengths of 550 and 428 nm. The change in the ratio of absorbance Δ550/Δ428 decreased linearly in a range of 0.01–5 ng mL?1, and the limit of detection was 67 pg mL?1. Therefore, the selectivity and reliability of this proposed method were well validated. This method was also successfully used for the quantitation of AFB1 in spiked rice flour and wheat flour samples. This approach may broaden the application field of colorimetric ELISA for aflatoxin, providing a promising platform for the rapid screening of aflatoxin in food.
      原文链接:
    • NSTL
    • Elsevier

    An aptasensing platform for detection of heat shock protein 70 kDa (HSP70) using a modified gold electrode with lady fern-like gold (LFG) nanostructure

    Negahdary M.Angnes L.
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Early diagnosis of diseases depends on accessibility and the ability to detect associated biomarkers. Using aptamers and equipping signal transducers with nanomaterials have facilitated, accelerated, and provided sensitive and selective nanoaptasensors. In this study, the first aptasensor to detect heat shock protein 70 kDa (HSP70) has been developed by applying a modified gold electrode (GE) with the lady fern-like gold (LFG) nanostructure. The nanostructure solution contained HAuCl4, H2SO4, and histamine and was electrochemically synthesized on the surface of the GE with an average size of ～20 nm. The analysis to find the optimized time for immobilization of aptamer (a single-stranded RNA) as the biorecognition element on the surface of the working electrode was performed using the open-circuit potential (OCP) technique. This aptasensor could detect HSP70 in a linear range from 0.05 to 75 ng mL?1 with the limit of detection (LOD) ～ 0.02 ng mL?1. In order to find out about the performance of the designed aptasensor, other analytical analyses for knowing about the figure of metrics were shadowed through reproducibility, stability, regeneration, selectivity, accuracy, and precision experiments.
      原文链接:
    • NSTL
    • Elsevier

    A sensitive photoelectrochemical aptasensor for enrofloxacin detection based on plasmon-sensitized bismuth-rich bismuth oxyhalide

    Dong J.Xu L.Dang S.Sun S....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Highly sensitive detection of enrofloxacin (ENR) is crucial for contaminant detection and environmental protection. A sensitive and selective photoelectrochemical (PEC) aptasensor was assembled by Au nanoparticles sensitized Bi24O31Br10 (Au/Bi24O31Br10) composites for detecting ENR. Due to the synergistic effect of bismuth-rich strategy and surface plasmon resonance (SPR) effect, Au/Bi24O31Br10 possessed promoted visible light absorption capacity further enhancing PEC performance and detection sensitivity of the constructed PEC aptasensor. By chemically adsorption effect between the sulfhydryl modified aptamer and Au nanoparticles, the ENR-aptamer was introduced into the PEC sensor to achieve highly selective detection of ENR. The PEC ENR aptasensor based on Au/Bi24O31Br10 composites possessed a broad linear detection scope (0.72–36000 ng L?1), satisfactory limit of detection (0.30 ng L?1, S/N = 3), high selectivity and stability. This work provides a new way for the trace detection of antibiotics in environmental analysis field.
      原文链接:
    • NSTL
    • Elsevier

    Equipment-free, gold nanoparticle based semiquantitative assay of SARS-CoV-2-S1RBD IgG from fingertip blood: A practical strategy for on-site measurement of COVID-19 antibodies

    Zhu Z.Zhu L.Luo Q.Lin N....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.COVID-19 remains as a major threat to human society. A reliable, sensitive, rapid, and low requirement assay for serum neutralizing antibodies is needed as a pandemic management tool for estimation of revaccination time and implementation of “immune passport”. Using gold nanoparticle (AuNR) as an immunosensor, we have established a semi-quantitative, instrument-free assay for measuring antibody level against SRAS-CoV-2 spike1 (S1) receptor binding domain (RBD) from fingertip blood samples. The testing results by the developed method correlated well with those obtained from conventional ELISA assay, indicating reliable quantitation could be achieved without use of plate reader. A declined of immunoglobulin G (IgG) antibody associated with vaccination time was observed, which agreed well with the data from other reports. The developed method provides a potentially complementary strategy for on-site measurement of COVID-19 antibodies.
      原文链接:
    • NSTL
    • Elsevier

    A new method for electrochemical determination of Hippuric acid based on molecularly imprinted copolymer

    Karazan Z.M.Roushani M.
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.This study introduces easy detection of Hippuric Acid (HA) through electrochemical polymerization technique. The molecularly imprinted polymer (MIP) was immobilized on a glassy carbon electrode (GCE) through electropolymerization of monomers, including m-dihydroxy benzene (m-DB) and o-aminophenol (o-AP), in presence of HA as the template. Moreover, it was subsequently delineated using electrochemical probe of hexacyanoferrate redox, atomic force microscopy (AFM), fourier-transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM) and electrochemical techniques such as cyclic voltammetry (CV), differential pulse voltammetry (DPV) and electrochemical impedance spectroscopy (EIS). This sensor exhibited limit of detection (0.012 nM) with a good linear range of 0.05–40 nM and 40–500 nM. The developed sensor was properly employed to determine HA in real samples with acceptable results.
      原文链接:
    • NSTL
    • Elsevier

    Direct and sensitive determination of Cu, Pb, Cr and Ag in soil by laser ablation microwave plasma torch optical emission spectrometry

    Zeng L.Wu M.Chen S.Zheng R....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Based on microwave plasma torch optical emission spectrometry combined with laser ablation, a direct solid sample detection device was developed for sensitive determination of heavy metals in soil. In the proposed laser ablation microwave plasma torch optical emission spectrometry (LA-MPT-OES) device, a new ablation chamber was designed, which the washout time and the relative standard deviation of this chamber were almost one-third of those of the conventional one, indicating that the proposed chamber had a smaller dead volume to provide efficient and stable transport of ablated sample particles. Meanwhile, to ensure a high signal intensity during a long exposure time, the moving sampling method was used to guarantee a sufficient injection amount. With the optimal experimental parameters, the limits of detection (LODs) of Cu, Pb, Cr and Ag were 0.075, 0.093, 0.068, 0.009 mg·kg?1, respectively, which was reduced by one to two orders of magnitude compared with that of laser-induced breakdown spectroscopy and X-ray fluorescence and was similar to the LODs of the digestion-required techniques (e.g., ICP-OES and MP-AES) and other LA-related techniques (e.g., LA-ICP-MS). Furthermore, the LA-MPT-OES was applied to the quantitative analysis of standard samples and actual samples, and the obtained determination results were in agreement with the standard values and that of atomic absorption spectrometry. The practicability and accuracy (relative errors were 0.95%–25.9%) of LA-MPT-OES determination of heavy metal elements were also validated.
      原文链接:
    • NSTL
    • Elsevier

    Detection of viruses by probe-gated silica nanoparticles directly from swab samples

    Tuna B.G.Durdabak D.B.Ercan M.K.Dogan S....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Viral infection has been one of the major health issues for human life. The real-time reverse transcription polymerase chain reaction (RT-PCR)-based detection has primarily been used for virus detection as a highly reliable procedure. However, it is a relatively long and multi-stage process. In addition, required skilled personnel and complex instrumentation presents difficulties in large scale monitoring efforts. Therefore, we report here a direct and fast detection method for CoV-2 genome as applied in the nose-throat swab samples without any further processing. The detection principle is based on fluorescein-loaded mesoporous silica nanoparticles capped by specific gene sequences probes immobilized on the surface of the nanoparticles. Upon hybridization with the target viral genome, the fluorescein molecules were released from the mesopores. Testing with synthetic oligonucleotides, the NSP12 gene-based detection resulted in a strong signal. Target detection time could be optimized to 15 min and the limit of detection was 1.4 RFU with 84% sensitivity with clinical samples (n = 43).
      原文链接:
    • NSTL
    • Elsevier

    Chemiresistive gas sensors based on electrospun semiconductor metal oxides: A review

    Chen L.Yu Q.Pan C.Song Y....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Semiconductor metal oxide (SMO) gas sensors have attracted considerable attention for detecting environmental pollution, as well as the accidental leakage of flammable, explosive, and toxic gases. SMOs are known to exhibit high sensitivity, fast response time, and excellent selectivity towards various types of gases. Many new strategies have been implemented to improve these characteristics. Among the materials produced by these methods, nanomaterials (NMs) synthesized by electrospinning have unprecedented advantages, including catalyst introduction, morphological control, thermodynamic stability, unique physicochemical properties, composition adjustment, and rapid adsorption–desorption rates of the NMs, and are appealing for the designing highly sensitive and selective gas sensors. This review highlights the latest findings on the design and fabrication of electrospun gas sensors for detecting various gases including hydrogen (H2), methane (CH4), nitrogen monoxide (NO), hydrogen sulfide (H2S), ammonia (NH3), ethanol (C2H5OH), acetone (CH3COCH3), formaldehyde (HCHO) and toluene (C6H5CH3). Studies have indicated that NMs with different shapes (e.g., nanotubes, nanowires, nanoflowers, nanosheets, nanorods, nanofilms, and nanofibers) and compositions (single-phase SMOs, modified SMOs, nanocomposites of SMOs, and SMOs combined with carbon nanomaterials) display high response values, long-term stability, low humidity dependence, fast response/recovery times, and low detection limits for gases. Finally, conclusions and future perspectives for gas sensors based on the electrospinning technique are discussed.
      原文链接:
    • NSTL
    • Elsevier

    A green photocatalytic-biosensor for colorimetric detection of pesticide (carbaryl) based on inhibition of acetylcholinesterase

    Peng L.Zhu J.Hao H.Lou S....
    5页
    查看更多>>摘要：? 2022 Elsevier B.V.Carbaryl is a widely-used carbamate pesticide and the detection of its residues in environmental, food and clinical samples is of great importance. In this sturdy, we developed a green photocatalytic-biosensor based on double strand DNA-SYBR green I complex for sensitively colorimetric detection of carbaryl. This green photocatalytic-biosensor can oxidize 3,3′,5,5′-tetramethylbenzidine (TMB) into blue ox-TMB. Meanwhile thiocholine is catalytically produced by acetylcholinesterase (AChE) to directly reduce blue ox-TMB into colorless TMB. But the activity of AChE will be suppressed by carbaryl, thus generating less thiocholine and resulting in more ox-TMB for colorimetric analysis. After the careful optimization of sensing conditions (2 μM for DNA concentration, 50 × concentration for SYBR Green I, 10 min for illumination time), the lowest detectable concentration for carbaryl is 0.008 ng/mL with a linear response in the range of 0.01–0.25 ng/mL. In addition, this photocatalytic-biosensor has good selectivity over non-target chemicals (acetamiprid, atrazine, carbendazim, melamine, bisphenol A, estradiol). It also allows detection of pesticides in real samples verified by a standard HPLC method.
      原文链接:
    • NSTL
    • Elsevier

    Evaluation of the variation in relative response factors of GC-MS analysis with the internal standard methods: Application for the alcoholic products quality control

    Korban A.Cabala R.Bosakova Z.Egorov V....
    5页
    查看更多>>摘要：? 2022This paper focuses on the evaluation of variation of relative response factors (RRFs) obtained by two internal standard (IS) methods that are used to control the quality of alcoholic products. A standard IS method using 1-pentanol was compared with an “Ethanol as IS” method. The variation of RRF values for both methods was determined using standard solutions based on 20, 40 and 96% ethanol-water matrices. For this purpose, solutions of the ten most abundant volatile compounds were analysed at four different concentrations (250, 500, 1000 and 5000 mg L?1 absolute alcohol, AA) within these matrices. Each solution was measured four times by gas chromatography-mass spectrometry (GC-MS) in single ion monitoring (SIM) mode under repeatability conditions. Our results showed that for the 40% and 96% matrices, the ethanol and standard IS methods showed similar relative standard deviations (RSDs) variation of no more than 2% within the 250–1000 mg L?1 AA volatile compounds concentration range. For the 20% matrix as well as for the 250–5000 mg L?1 AA concentration range the resulting variation in calibration factors reaches 10% for both methods. As for the whole range of 20–96% alcohol by volume (ABV) and 250–5000 mg L?1 AA volatile concentration range, the resultant RRFs for the standard IS method (8% RSD) were more stable than those for the ethanol IS method (almost 40% RSD). Nonlinearity of the signal-to-amount dependence was also assessed with respect to the injection and detection processes.
      原文链接:
    • NSTL
    • Elsevier