Ahmed S.A.Khojah H.M.J.Al-Thagfan S.S.Alahmadi Y.M....
11页
查看更多>>摘要：It is established that vitamin D deficiency is correlated with the disease severity in COVID-19 patients. However, the reliable and sensitive quantitation of vitamin D3 (D3) and its metabolites remains a difficult challenge. Herein, a novel ultrasensitive and reliable UHPLC-ESI-MS/MS method was developed and validated for the quantitation of D3 and its major metabolites in COVID-19 patients. The mass spectral sensitivity was augmented via controlled microwave-assisted derivatization reaction (CMDR) with 2-nitrosopyridine (Pyr-NO) at 65 °C for 2 min. CMDR hyphenation with UHPLC-MS/MS improves detection sensitivity while shortening separation and derivatization reaction times. The precursor to product ion transitions for D3, 25-hydroxy D3 (25(OH)D3), 1,25-dihydroxy D3 (1,25-(OH)2D3) and calcipotriol (CPT) as an internal standard were m/z 493.4 → 231.3, m/z 509.4 → 231.3, m/z 525.4 → 247.3, and m/z 521.4 → 247.3; respectively. The separation of the formed derivatives was conducted using a gradient elution mode with mobile phase A: formic acid (0.1%) in water and mobile phase B: formic acid (0.1%) in acetonitrile. The elution started with 40% (v/v) of B for 0.3 min then increased linearly to 90% (v/v) at 2 min on an Agilent EclipsePlus C18 (50 × 2.1 mm, 1.8 μm) column at a flow rate of 0.3 mL min?1. The method was validated using FDA standards for bioanalytical method validation over a concentration range of 0.02–50 ng mL?1 with correlation coefficient ≥0.9987 and the lower limit of quantitation (LLOQ) were 0.02–0.05 ng mL?1 in human plasma. The developed method has demonstrated excellent comparability to a well-established chemiluminescent immunoassay (CLIA) method for the analysis of D3 metabolites in human samples. The developed UHPLC-ESI-MS/MS method was implemented for routine and reliable quantitation of D3 and its major metabolites in COVID-19 patients.
查看更多>>摘要：Rapid, sensitive and specific determination of circular RNA (circRNA) is of great significance for both biological research and clinical diagnosis. Specific recognition of target circRNA is now facing major challenges due to the fact that large amount of corresponding linear RNA is coexisting and possesses the same sequences except the junction sequence of circRNA. Herein, we firstly utilize CRISPR/Cas13a to specifically recognize the unique junction sequence of target circRNA and innovatively develop a CRISPR/Cas13a induced exponential amplification assay for sensitive and specific detection of circRNA. A pair of stem-loop DNA primers are elaborately designed with a pair of complementary single-strand DNA and five uracil ribonucleotides as the cantilever at their 3′ terminus. Once Cas13a recognizes target circRNA, the trans-cleavage activity of Cas13a can be activated and the uracil ribonucleotides will be cleaved. Thus, the 3′ terminus of the stem-loop primers can extend along each other to generate a lot of double stem-loop DNAs which can initiate multiple loop-mediated isothermal amplification (LAMP). Taking advantage of the incessant cleavage activity of Cas13a and the high amplification efficiency of multiple LAMP reaction, as low as 1 fM target circRNA can be sensitively detected within 30 min. Due to the high specificity of Cas13a, the proposed assay has been successfully applied to the detection of circRNA in real biological samples without separation of corresponding linear RNAs. Moreover, the proposed assay has offered a versatile platform for the detection of all sequence-specific RNA targets, indicating that our CRISPR/Cas13a induced exponential amplification assay has great potential for the detection of RNA biomarkers in both fundamental studies and clinical diagnostics.
查看更多>>摘要：? 2022 Elsevier B.V.Fabrication of facile, sensitive, and accurate pesticide detection strategies plays crucial roles in food safety, environmental protection, and human health. Here, a novel esterase activatable aggregation-induced emission (AIE) plus excited-state intramolecular proton transfer (ESIPT) probe, kaempferol tetraacetate, was designed and synthesized from purified natural kaempferol for ratiometric sensing of carbaryl. Acetate groups are introduced as the esterase reactive sites and AIE plus ESIPT initiator. Kaempferol tetraacetate is an aggregation-caused quenching compound that shows fluorescent (FL) emission at 415 nm. Esterase specifically hydrolyzes kaempferol tetraacetate to kaempferol with AIE plus ESIPT characteristics (distinct FL emission, 530 nm; a large Stokes shift, 165 nm within a short time (8 min). Molecular docking and kinetics performance indicate the high affinity and specific hydrolysis of esterase and kaempferol tetraacetate. Carbaryl inhibits the activity of esterase to efficiently suppress the production of kaempferol. Thus, a facile ratiometric assay strategy is constructed for carbaryl detection. By measuring the FL intensity ratio, the proposed strategy presents high selectivity and reliability with a wide linear range from 0.02 to 2.00 μg L?1 and a very low limit of detection at 0.007 μg L?1. Furthermore, appropriate recovery from 93.75% to 108.67% with a relative standard deviation less than 5.66% for real sample analysis indicates good accuracy and precision. All results indicate that the fabricated strategy offers a new way for facile, sensitive, and accurate detection of carbaryl in real complex samples.
查看更多>>摘要：? 2022In the present work we have developed two hierarchical nano-architectures based electrochemical immunosensors for the detection of interleukin-8 (IL-8) cytokine tumor biomarker. A comparative study has been performed for spatial nano-architectures and their relative sensing to establish the model for real time monitoring. With the first platform, the recognition layer consisted with immobilised IL-8 on aminothiol modified gold electrodes. In the second approach, the activated multi walled carbon nanotubes (MWCNT-COOH) were added in the functionalisation process by covalent attachment between the functionalities NH2 of aminothiol and the functionalities COOH of carbon nanotubes. The surface topology of the recognition layer has been characterised by atomic force spectroscopy (AFM) and contact angle (CA) measurements. The electrochemical response of the developed sensor was measured by electrochemical impedance spectroscopy (EIS). A side-by-side comparison showed that aminothiol/activated MWCNTs/anti-IL-8 based impedimetric immunosensor exhibits high reproducibility (The relative standard deviation (R.S.D) = 3.2%, n = 3) with high stability. The present sensor allows evaluating a lower detection limit of 0.1 pg mL?1 with a large dynamic sensitivity range from 1 pg mL?1to 1000 pg mL?1 covering the entire clinical therapeutic window. The developed MWCNTs based immunosensor has been calibrated by determining IL-8 in artificial plasma and showed a selective response to IL-8 even in the interfering environment of other cytokines such as Interleukin-1 (IL-1) and Interleukin-6 (IL-6).
查看更多>>摘要：? 2022 Elsevier B.V.Since silver ion is known for its antimicrobial function, most of the research has focused mainly on toxicity effects rather than the role of silver ion in general biology and the behind mechanism of actions of silver ion in mammalian cells. Moreover, a conventional in vitro approach to estimate the effects of silver ion on cells does not provide information about the biochemical changes and might accompany artifacts due to invasive and destructive sample preparation processes. In the present study, in-situ real time approaches were applied to evaluate the impact of silver ion (0.57, 1.34, 1.96, 2.33 mg/L) on fibroblast cells. Raman spectroscopy analysis showed that Raman peak intensities of proteins and nucleic acids significantly increased in the cells after exposure to silver ion for 21 h, especially at relatively higher levels 1.34, 1.96, and 2.33 mg/L. Raman peak at 1585 cm?1 and liquid scanning transmission electron microscopy energy-dispersive x-ray spectroscopy (STEM-EDS) analysis revealed the fate of silver ion that was taken up by the cell and reduced into metallic silver accumulating in the cell as silver nanoparticles. These results suggest cells were undergoing different activities such as enhanced metabolic activities rather than cell apoptosis or cell death. Additionally, Raman spectroscopy predicted the level of silver ion exposed to the cell at 2.11 ± 0.38 and 1.73 ± 0.26 mg/L by the PLS prediction model, compared with the results measured by inductively coupled plasma mass spectrometry (ICP-MS), 2.14 ± 0.07 and 1.87 ± 0.07 mg/L respectively, suggesting Raman spectroscopy can provide a new and fast approach to determine and measure the concentration of silver ion or probably other tested molecules treated to the cell for the future research.
Ferreira L.F.Pio dos Santos W.T.Porto L.S.Pereira A.C....
5页
查看更多>>摘要：? 2022 Elsevier B.V.This work presents, for the first time, a fast and highly sensitive electrochemical method for determination of three organophosphorus compounds (OPs), diazinon (DZN), malathion (MLT), and chlorpyrifos (CLPF), using a modified pyrolytic graphite electrode (PGE) coupled to batch injection analysis system with multiple pulse amperometric detection (BIA–MPA). The PGE was modified by a nanocomposite based on functionalized carbon nanotubes (CNTf) and silver nanoparticles (AgNPs). The OPs samples were directly analyzed on the modified working electrode surface by BIA-MPA system in Britton-Robinson (BR) buffer 0.15 mol L?1 at pH 6.0. The MPA detection of DZN, MLT and CLPF was performed using two potential pulses, which were sequentially applied on modified PGE at ?1.3 V (100 ms) and +0.8 V (100 ms) for selective determination of these three OPs and working electrode cleaning, respectively. Under optimized conditions, the sensor presented a linear range of 0.1–20 μmol L?1 for DZN, 1.0–30 μmol L?1 for MLT and from 0.25 to 50 μmol L?1 for CLPF. The limits of detection (LOD) and quantification (LOQ) of 0.35 and 1.18 μmol L?1 for DZN, 0.89 and 2.98 μmol L?1 for MLT, and 0.53 and 1.78 μmol L?1 for CLPF were obtained. The proposed method exhibited high sensitivity of 0.068, 0.030 and 0.043 mA L μmol?1 for DZN, MLT and CLPF detection, respectively. Furthermore, the BIA-MPA system provided an analytical frequency of 71 determinations per hour for direct determination of these OPs in water and food samples. The modified PGE coupled to BIA-MPA system showed a high stability of electrochemical response for OPs detection with relative standard deviation (RSD) of 1.60% (n = 20). The addition-recovery studies of the proposed method were carried out in tap water, orange juice, and apple fruit real samples, which showed suitable recovery values between 77 and 124%. The analytical performance of the developed sensor provides an attractive alternative method for OPs determination with great potential for a fast and sensitive application in contaminated samples with these pesticides.
查看更多>>摘要：? 2022 Elsevier B.V.Okadaic acid (OA), dinophysistoxin-1 (DTX-1), and dinophysistoxin-2 (DTX-2) are the main diarrheic shellfish poisons (DSPs). Detection methods to achieve simultaneous detection of the three toxins are urgently needed. In this paper, a terminal fixation design proposed in our previous study was further explored to engineer an aptamer with group-specific recognition ability from an original aptamer binding to one target. Both molecular docking assay and biolayer interferometry assay were applied to reveal the binding mechanisms between three DSPs and the engineered aptamer. Then, a label-free colorimetric aptasensor by fabricating the aptamer with AuNPs@Fe2+ nanozyme was constructed, which provided a wide linear detection range (0.4688–7.5 nM), a very low limit of detection (LOD, 86.28 pM), and good recoveries (96.02–104.9%) when analyzing DSPs in seawater and scallop samples, indicating the engineered aptamer and the developed aptasensor had great potential in recognizing and detecting multiple DSPs in real world.
查看更多>>摘要：? 2022 Elsevier B.V.Most prism-based surface plasmon resonance (SPR) experiments use matching fluid with a similar refractive index to mount the chip on the optical prism. The fluidity of the matching fluid easily affects the transmission of the optical signal. In this paper, an integrated SPR sensor chip comprises a three-layer structure of flow layer, metal layer and refractive index matching layer is demonstrated to address the problems related to consistency and uniformity. The Young's modulus, array spacing, shape and other parameters of the matching film were calculated and optimized. The chip can self-adhere to the optical prism, and effectively avoids the generation of air bubbles. The refractive index detection sensitivity of the integrated SPR sensor chip was 3.4359 × 10?6 RIU (refractive index unit), and the chip stabilization time has been effectively shortened. The integrated SPR sensor chip was also used to detect kappa light chain protein and human serum albumin (HSA) in urine samples. The detection limit of kappa light chain protein was 0.06 μg/mL compared with 18.5 μg/mL by conventional immunoturbidimetry. The integrated SPR sensor chip based on refractive index matching film array has great potential in biomedical detection and other fields, including point-of-care testing (POCT).
查看更多>>摘要：? 2022 Elsevier B.V.To detect silver ions conveniently and rapidly in vitro and in vivo, a selective fluorescent probe with a wide measurement range, AgP, was developed. This probe exhibits a bright green fluorescence with an emission wavelength of 532 nm under 390 nm excitation, and its detection of Ag+ is stable in the pH range of 4–10 with a quench-type fluorescence response. Specially, the probe and its easily prepared test strips can be directly used for the colorimetric detection of Ag+ in aqueous samples with simple and convenient characteristics, the color change can be observed within a few seconds. The recovery rate of AgP detection water samples was between 117.6% and 98.3%, and the relative standard deviation (RSD) was between 0.41% and 2.06%. AgP is also suitable for in vivo imaging of Ag+ in the classical model plant, Arabidopsis thaliana, and 50 μM Ag+ can completely quench its fluorescence, which will provide a new detection tool for studying the distribution of Ag+ in the environment and live plants.
查看更多>>摘要：? 2022 The AuthorsSystematic errors in the calix [4] pyrrole-based potentiometric detection of creatinine have been observed in heavy smokers. This work further characterizes the interactions between the nicotinium cation and the cavitand as well as the resulting interference produced during the potentiometric detection. It is found that the nicotinium cation binds the electronic rich aromatic cavity defined by the pyrrole rings of the receptor's cone conformation with an estimated binding constant higher than 10?4 M?1 in methylene chloride. On the other hand, the creatininium cation is preferentially included in the hydrophobic aromatic cavity of the ionophore by establishing hydrogen bond interactions with the pyrrole NHs groups. Potentiometric calibrations confirmed the detection of the nicotinium cation at neutral and acidic pH, respectively. Due to the lower pka of creatinine, a methodology to quantify creatinine in presence of nicotine by using an array of three sensors at two pH values is proposed. A partial least squares regression was performed and reported recoveries of 103% with a standard deviation of 20%. The improved determination of creatinine was therefore discussed. This approach represents a step forward in the development of effective approaches to improve the measurement of creatinine in decentralized settings.
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