查看更多>>摘要：Cannabis is currently one of the most consumed drugs in many countries. Delta(9)-tetrahydrocannabinol (THC) is the principal psychoactive component of this drug and is present in saliva after consumption. This paper reports a novel biomolecule-free electrochemical approach to detect an ultra-low level of THC in saliva using modified electrodes with molecules of the same analyte (THC) that are detected later via square wave voltammetry. The results from this research revealed that the electmdeposition of THC on the working electrode (sensor analyte) could highly enhance the limit of detection by improving the affinity of the THC molecules present in the sample (sample analyte) to the sensing electrode surface. Detailed descriptions about the optimization of the sensor and its performance in simple media, such as PBS, and complex media, such as simulated and real saliva, are provided. This novel and yet simple electrochemical-based sensing strategy allowed for a low limit of detection of 1.6 ng/mL THC in simulated and real saliva, distinguishing concentrations ranging from 2 to 25 ng/mL, making this technology viable for a real-world application such as roadside testing.
Killner, Mario Henrique M.de Aguiar, Leticia MagalhaesGalvan, DiegoBona, Evandro...
10页
查看更多>>摘要：Medium-resolution (MR-NMR) and time-domain NMR relaxometry (TD-NMR) using benchtop and low-field NMR instruments are powerful tools to tackle fuel adulteration issues. In this work, for the first time, we investigate the possibility of enhancing the low-field NMR capability on fuel analysis using data fusion of MR and TD-NMR. We used the ComDim (Common Dimensions Analysis) multi-block analysis to join the data, which allowed exploration, classification, and quantification of common adulterations of diesel fuel by vegetable oils, biodiesel, and diesel of different sources as well as the sulfur content. After data exploration using ComDim, classification (applying linear discriminant analysis, LDA), and regression (applying multiple linear regression, MLR), models were built using ComDim scores as input variables on the LDA and MLR analyses. This approach enabled 100% of accuracy in classifying diesel fuel source (refinery), sulfur content (S10 or S500), vegetable oil, and biodiesel source. Moreover, in the quantification step, all MLR models showed a root mean square error of prediction (RMSEP) and the residual prediction deviation (RPD) values comparable to the literature for determining diesel, vegetable oil, and biodiesel contents.
Hosny, Noha M.Gadallah, Mohammed I.Gomila, Rosa M.Qayed, Wesam S....
8页
查看更多>>摘要：A novel computationally designed-spectrofluorimetric method for the determination of a unique antinarcoleptic drug; modafinil (MDF) in tablets and human plasma was theoretically and experimentally established. Firstly, a density functional theory (DFT) computations were performed to investigate MDF-Tb3+ complex formation and to study the affinity of Tb3+ to MDF in aqueous solution. The computed formation energy of [Tb (MDF)(4)](3+) (Delta G=-246.0 kcal/mol) assured the ability of Tb3+ to recognize MDF in water and proved the strong nature of the Tb3+-O coordination bonds in addition to some contribution from inter-ligand hydrophobic interactions. Hence, a spectrofluorimetric method was optimized and validated depending on MDF quenching effect on Tb3+ fluorescence via fluorescence resonance energy transfer from Tb3+ to MDF. The formed [Tb (MDF)(4)](3+) complex was measured at lambda(ex). 222 nm/lambda(em). 497 nm against a reagent blank. The Tb3+ fluorescence was significantly reduced upon addition of MDF (linearity range= 0.5-20.0 mu g/mL). Detection and quantification limits were 0.129 and 0.391 mu g/mL, respectively. Good recoveries (97.47-101.92%) were obtained upon application of the proposed method for the assessment of the target drug in bulk powder, tablets and plasma. According ICH guidelines, the results of the established method were statistically analyzed and validated.
Synovec, Robert E.Ochoa, Grant S.Sudol, Paige E.Trinklein, Timothy J....
10页
查看更多>>摘要：Tile-based Fisher ratio (F-ratio) analysis is emerging as a versatile data analysis tool for supervised discovery based experimentation using comprehensive two-dimensional (2D) gas chromatography coupled with time-of flight mass spectrometry (GC x GC-TOFMS). None the less, analyte identification can often be marred by poor 2D resolution and low analyte abundance relative to overlapping compounds. Linear algebra-based chemometric methods, in particular multivariate curve resolution alternating least squares (MCR-ALS), parallel factor analysis (PARAFAC) and PARAFAC2, are often applied in an effort to address this situation. However, these chemometric methods can fail to produce an accurate spectrum when the analyte is at low 2D resolution and/or in low relative abundance. To address this challenge, we introduce class comparison enabled mass spectrum purification (CCE-MSP), a method that utilizes the underlying requirement for signal consistency of the background interference compounds between the two classes in the F-ratio analysis to purify the mass spectrum of the analyte hits. CCE-MSP is validated using a dataset obtained for a neat JP-8 jet fuel spiked with 14 sulfur containing compounds at two levels (15 ppm and 30 ppm), using the p-value and lack-of-fit (LOF) for each analyte hit as consistency metrics. A purified mass spectrum was produced for each spiked analyte hit and their mass spectrum match value (MV) was compared to the MV obtained by MCR-ALS, PARAFAC, and PARAFAC2. The resulting MV for CCE-MSP were found to be as good or better than these chemometric methods, eg., for 2butyl-5-ethylthiophene with an analyte-to-interference relative signal abundance of 1:87 and a 2D resolution of 0.2, CCE-MSP produced a MV of 831, compared to 476 for MCR-ALS, 403 for PARAFAC, and 336 for PARAFAC2. CCE-MSP is also extended to obtain the purified spectrum for more than one analyte, eg., two analyte hits in overlapping hit locations. The spectra produced by CCE-MSP can also be utilized as estimates to facilitate quantitative signal decomposition using MCR-ALS.
查看更多>>摘要：Acetone serves as a routine solvent and synthetic intermediate in chemical factories and laboratories. Monitoring the level of acetone vapor in working environment is of great necessity to employee health due to its strong volatility and toxicity, but there is still in lack of simple and easy-to-use portable sensors. In this study, we report a portable and intuitive indicator for real-time displaying acetone vapor concentration in air, based on the ratiometric fluorescence response of the designed organic molecule, PhB-SSB, to acetone. As an aggregation-induced emission (AIE) fluorophore, PhB-SSB underwent specific reaction with acetone through the salicy-laldehyde Schiff base and phenylboronate groups to realize ratiometric fluorescence change from green to red after acetone vapor treatment. The reaction mechanism was proposed as acetone-induced breakage of the imine bond in PhB-SSB. We further fabricated PhB-SSB into a film fluorescent sensor for acetone vapor with good sensitivity and selectivity. Taking advantage of its intuitive fluorescent color contrast, acetone-specific response and small size, our sensor is practical in real-time alarming the acetone vapor hazard in the workplaces.
Dias, DaianeMaciel, Juliana Villelada Silveira, Gessica DomingosDurigon, Ana Maria Munaretto...
8页
查看更多>>摘要：For the first time carbon black based electrode modified with paraffin was applied as a sensor on voltammetry of immobilized microparticles (VIMP) approach for determination of lead solid residues in hair dye samples. The solid microparticles of Pb(II) (Pb(CH3COO)(2(s))) immobilized into the carbon paste sensor containing carbon black and paraffin were firstly reduced at initial potentials and further reoxidized at around -0.60 V during anodic scan. Electroanalytical parameters as well as supporting electrolyte composition, and pH were also evaluated. An analytical curve in 0.2 mol L-1 phosphate buffer solution (pH 5.0) from 0.04 to 3.2 mu g (R-2 = 0.999) with detection and quantification limits of 4 and 13 ng, respectively, were achieved. The method was applied to quantify lead solid residues in hair dye samples without previous mineralization or complex sample pre-treatment. Besides adequate repeatability, stability and selectivity of the developed sensor based on VIMP fea-tures, the method using carbon black based sensor was considered advantageous comparing to the results recorded by a spectrometric method (relative error lower than 8%) from several analytical viewpoints.
查看更多>>摘要：A quartz crystal microbalance (QCM) sensor was developed in this study with the vegetable oil from olive (OLV-QCM) to detect an important volatile organic compound, beta-pinene in Indian cardamom. Hydrophobic vegetable oil from olive, which contains oleic acid and omega-9, a monounsaturated fatty acid was found to be suitable for binding beta-pinene through non-covalent bonds. The fabricated QCM sensor coating was examined with the field emission scanning electron microscope (FESEM) and Fourier-transform infrared spectroscopy (FTIR) to determine its surface morphology and chemical compositions. The sensitivity, reproducibility, repeatability, and reusability were studied for the developed sensor. Notably, the sensor was observed to be highly selective towards beta-pinene as compared to the other volatile components present in cardamom. The limit of detection (LOD) and limit of quantitation (LOQ) parameters were determined as 5.57 mg L-1 and 18.57 mg L-1, respectively. Moreover, the adsorption isotherm models of the sensor were studied to validate the physical adsorption affinity towards beta-pinene applying Langmuir, Freundlich, and Langmuir-Freundlich isotherm models. The sensor showed a correlation factor of 0.99 with the peak area percentage of gas chromatography-mass spectrometry (GC-MS) analysis for beta-pinene in cardamom samples. The sensor was prepared with natural vegetable oil, unlike health hazard chemicals. In addition to this, the low-cost, easy fabrication process ensured the suitability of the sensor for practical deployment.
查看更多>>摘要：A rapid detection test for SARS-CoV-2 is urgently required to monitor virus spread and containment. Here, we describe a test that uses nanoprobes, which are gold nanoparticles functionalized with an aptamer specific to the spike membrane protein of SARS-CoV-2. An enzyme-linked immunosorbent assay confirms aptamer binding with the spike protein on gold surfaces. Protein recognition occurs by adding a coagulant, where nanoprobes with no bound protein agglomerate while those with sufficient bound protein do not. Using plasmon absorbance spectra, the nanoprobes detect 16 nM and higher concentrations of spike protein in phosphate-buffered saline. The timevarying light absorbance is examined at 540 nm to determine the critical coagulant concentration required to agglomerates the nanoprobes, which depends on the protein concentration. This approach detects 3540 genome copies/mu l of inactivated SARS-CoV-2.
查看更多>>摘要：Rapid diagnosis of tuberculosis disease (TB) still remained a pressing need for TB control efforts all over the world. However, the existing detection approaches cannot satisfy demand of rapid detection of clinical Mycobacterium tuberculosis (M. tuberculosis) because of the long detection time and high cost. Herein, we proposed a new M. tuberculosis piezoelectric sensor based on AuNPs-mediated enzyme assisted signal amplification. A hairpin-shaped DNA duplex with a protrusion of the 3' end was designed. In the presence of specific 16 S rDNA fragment of M. tuberculosis, the hairpin probe was opened, which triggered the selective cleavage of hairpin probe by Exonuclease III (Exo III), resulting in the release of uncut DNA probe and target DNA. The released target DNA hybridized with another hairpin-shaped DNA duplex, and a new digestion cycle was started, thus generating large amounts of uncut DNA probes. The uncut DNA was pulled to the electrode surface by the hybridization with capture probe modified on the electrode. Subsequently detection probe labeled AuNPs was hybridized with uncut DNA and entered between the two electrodes. The AuNPs linked to hybridized detection probe were grown in the HAuCl4 and Nicotinamide adenine dinucleotide (NADH) solution and offered the conductive connection between the gaps of electrode. The changes were monitored by the piezoelectric sensor. The piezoelectric biosensor could achieve a detection of M. tuberculosis (10(2)-10(8) CFU mL(-1)) within 3 h, the detection limit (LOD) was 30 CFU mL(-1). The methodology could be transformed into different microbial targets, which is suitable for further development of small portable equipment and multifunctional detection.
查看更多>>摘要：Bispecific antibodies (bsAbs) are considered as an important class of biopharmaceutical drugs, with about 160 products in clinical trials. From an analytical point of view, the correct chain-association is one of the most critical challenge to monitor during bsAbs development and production. In the present study, a full analytical workflow has been developed based on the use of various chromatographic modes: size exclusion chromatography (SEC), ion exchange chromatography (IEX), reversed phase liquid chromatography (RPLC), and hydrophilic interaction chromatography (HILIC), all combined with high resolution mass spectrometry (MS). This analytical strategy was applied to Hemlibra (R) (emicizumab), which is certainly the most successful commercial bsAb to date. Using this strategy, it was possible to monitor the presence of mispaired bsAb species and detect and identify additional post-translational modifications (PTMs).
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