查看更多>>摘要：A selective method for preconcentration and determination of methylmercury (MeHg) and inorganic mercury (iHg) in natural water samples at the ng L-1 level has been developed. The method involves adsorption of Hg species into a 3D printed metal scavenger and sequential elution with acidic thiourea solutions before ICP-MS determination. Experimental parameters affecting the preconcentration of MeHg and iHg such as the sample matrix, effect of the flow rate on adsorption, eluent composition, and elution mode have been studied in detail. The obtained method detection limits, considering the preconcentration factors of 42 and 93, were found to be 0.05 ng L-1 and 0.08 ng L-1 for MeHg and iHg, respectively. The accuracy of the method was assessed with a certified groundwater reference material ERM-CA615 (certified total iHg concentration 37 +/- 4 ng L-1). The determined MeHg concentration was below MDL while iHg concentration was determined to be 41.2 +/- 0.5 ng L-1. Both MeHg and iHg were also spiked to natural water samples at 5 ng L-1 concentration and favorable spiking recoveries of 88-97% were obtained. The speciation procedure was successfully applied to two lake water samples where MeHg and iHg concentrations ranged from 0.18 to 0.24 ng L-1 and 0.50-0.62 ng L-1, respectively. The results obtained demonstrate that the developed 3D printed metal scavenger-based method for preconcentration and speciation of Hg is simple and sensitive for the determination of Hg species at an ultra-trace level in water samples.
查看更多>>摘要：In this work, ferrous disulfide nanoparticles (FeS(2)NPs) with oxidase properties were synthesized, and a FeS(2)NPs-Luminol-MnO2 nanosheets (MnO(2)NSs) chemiluminescence resonance energy transfer (CRET) system was successfully established. Because of reaction with MnO(2)NSs, glutathione (GSH) can inhibit CRET between Luminol and MnO2NSs and recover the luminescence intensity of FeS(2)NPs-Luminol. Consequently, we developed a GSH sensor based on this chemiluminescence resonance energy transfer (CRET) system. Under optimal conditions, the FeS(2)NPs-Luminol-MnO(2)NSs sensing system showed very sensitive response to GSH in the range of 1 mu M-500 mu M. The limit of detection of GSH reached as low as 0.15 mu M. Finally, the sensor was successfully used for the detection of GSH in serum.
查看更多>>摘要：We recently reported on fixed-path length laser-induced sound pinging (FPL-LISP) as a rapid photoacoustic technique employing an inexpensive benchtop tattoo-removal laser for reliably determining the speed of sound in low-volume fluids. In this contribution, we demonstrate the capacity of FPL-LISP to analyze representative commercial beverages for their natural or artificial sweetener contents. As a benchmark, the speed of sound was determined for solutions of sugars (glucose, fructose, sucrose), mock high fructose corn syrup (HFCS-55), and 12 household sweeteners (culinary sugars, syrups, honey, molasses) across the concentration range of 1-20% w/v in water, simulating the typical sweetener range found in commercial soft drinks. The setup was then employed to estimate sweetener contents of 26 popular commercial beverages using the HFCS-55 standard curve as a training data set. Our results are remarkably consistent with the label values for these representative commercial beverages, in spite of the fact that some beverages clearly employ a sweetener other than HFCS-55 or a proprietary blend, suggesting the excellent potential of the FPL-LISP setup as a quick screening tool well-suited to quality control and real-time assessment in the beverage and fermentation industrial sectors. The proposed approach represents a significant improvement over many existing methods on the basis of measurement time (down to 1 s, which can be considered real time for many applications), lenient sample requirements (tens of microliters to 1 mL), robust and user-friendly analysis, practical considerations (e.g., economical, minimal service and maintenance concerns), and prospects for advancing both online monitoring and fully portable versions of this instrumentation.
查看更多>>摘要：Protein biomarkers of intracranial aneurysm (IA) are essential for early detection and prediction of its rupture to facilitate the diagnosis and clinical management of the disease, monitor treatment response and detect recurrence. Here, we developed a comprehensive strategy for IA biomarker discovery by analyzing tissues from an animal model (n = 4) and serum from human patients (n = 60) using isobaric tandem mass tags-based quantitative proteomics. A total of 4811 and 562 proteins were identified from aneurysm tissue and serum samples, respectively. The 223 candidate protein biomarkers were further validated in an independent serum cohort (n = 30) by multiple reaction monitoring analysis. Combined with a logistic regression model, we built a diagnostic classifier P2 (FCN2 & RARRES2) to differentiate IA from healthy controls with accuracy of 93.3%, as well as a diagnostic classifier P7 (ADAM12, APOL3, F9, C3, CEACAM1, ICAM3, KLHDC7A) to classify ruptured IA from unruptured IA with accuracy of 95.0%. Taken together, our results suggest a valuable strategy for biomarker discovery and patient stratification in IA.
查看更多>>摘要：The use of mass spectrometry methods with triple quadrupole instruments is well established for quantification. However, the preparation of calibration curves can be time-consuming and prone to analytical errors. In this study, an innovative internal calibration (IC) approach using a one-standard calibration with a stable isotope-labeled (SIL) standard version of the endogenous compound was developed. To ensure optimal quantitative performance, the following parameters were evaluated: the stability of the analyte-to-SIL response factor (RF), the chemical and isotopic purities of the SIL, and the instrumental reproducibility. Using six clinically important endogenous steroids and their respective SIL standards, we demonstrated that RFs obtained on different LC-MS platforms were consistent. The quantitative performance of the proposed approach was determined using quality control samples prepared in depleted serum, and showed both satisfactory precision (1.3%-12.4%) and trueness (77.5%-107.0%, with only 3 values outside +/- 30%). The developed method was then applied to human serum samples, and the results were similar to those obtained with the conventional quantification approach based on external calibration: the Passing-Bablok regression showed a proportional bias of 6.8% and a mean difference of -5.9% between the two methodologies. Finally, we showed that the naturally occurring isotopes of the SIL can be used to provide additional calibration points and increase the accuracy for analytes with low concentrations.
El-Sharif, Hazim F.Turner, Nicholas W.Reddy, Subrayal M.V. Sullivan, Mark...
8页
查看更多>>摘要：Molecularly imprinted polymers (MIPs) are fast becoming alternatives to biological recognition materials, offering robustness and the ability to work in extreme environments. Here, a modified thymine-based nucleobase, with acrylamide at the 5-postion (AA-dT) was used as a co-monomer in the synthesis of a thin-film electropolymerised MIP system for the molecular recognition of the protein haemoglobin. The AA-dT co-monomer incorporated into a N-hydroxymethylacrylamide (NHMAm) MIP offered a two-fold superior binding affinity of the NHMAm only MIP, with K-D values of 0.72 mu M and 1.67 mu M, respectively. A unique AA-dT:NHMAm MIP bilayer was created in an attempt to increase the amount AA-dT incorporated into the film, and this obtained a respectable K-D value of 7.03 mu M. All MIPs produced excellent selectivity for the target protein and when applied to a sensor platform (Surface Plasma Resonance), the limit of detection for the MIPs is in the nM range (3.87, 3.47, and 3.87 nM, for the NHMAm MIP, AA-dT:NHMAm MIP, and AA-dT:NHMAm MIP bilayer, respectively). The introduction of the modified thymine-based nucleobase offers a promising strategy for improving the properties of a MIP, allowing these MIPs to potentially be a highly robust and selective material for molecular recognition.
Silveri, FilippoDella Pelle, FlavioScroccarello, AnnalisaBukhari, Qurat Ul Ain...
8页
查看更多>>摘要：In this work, a redox-graphene (Rx-Gr) film with electron-mediating ability has been integrated into a modular flexible pocket device, giving rise to a reusable biosensing platform. The Rx-Gr has been obtained in water from graphite taking advantage of catechin, a redox-antioxidant, able to assist the sonochemical layered-material exfoliation, conferring electron mediating feature. A film composed exclusively of Rx-Gr has been transferred via thermal rolling onto a flexible PET-support that was used as the biosensor base. The biosensing platform, composed of office-grade materials, was then fabricated using a cutter plotter and assembled by thermal lamination; an interchangeable paper-based strip was used to host the enzymatic reaction and drive the capillary flow. An acetylcholinesterase-based inhibition assay has been optimized onboard the pocket device to determine chlorpyriphos, a widespread environmental pesticide. The proposed set-up allows the determination of chlorpyriphos at low overpotential (0.2 V) with satisfactory sensitivity (LOD = 0.2 ppb), thanks to the straightforward electroactivity of the Rx-Gr film towards thiocholine (enzymatic product). The modular design allows 5 consecutive complete inhibition assays (control + inhibition measure) retaining the performance (RSD = 5.4%; n = 5). The coupling of bench-top technologies and a new functional graphene film resulted in the development of a cost-effective, reusable, transportable, and within everyone's reach biosensing platform.
查看更多>>摘要：Here is examined the colour development from common anthocyanins (i.e., cyanidin, delphinidin, malvidin, and pelargonidin glycosides) and from anthocyanins-rich extracts (i.e., bilberries, strawberries, and raspberries), using zinc-anthocyanin complexes as molecular probe. We have observed the absorbance increase in the blue region in presence of large excess of zinc ion at acidic pH for cyanidin and delphinidin derivatives, likely due to quinoidal base stabilization from catechol and pyrogallol moiety. The assay condition were studied and applied to natural extracts containing these compounds. The same behaviour was observed for bilberry and, to a minor extent, for raspberry extracts, due to the larger cyanidin/delphinidin contents in the former than in the latter. Anthocyanin standard UV-Vis analysis in buffer has shown a very good linear correlation for cyanidin and delphinidin (R-2 = 0.995 and 0.997, respectively), good precision (CV% = 7.4% and 5.3% respectively), high sensitivity (Cy epsilon(600nm) = 8300 M-1 cm(-1), LOD = 0.264 +/- 0.005 mg L-1, LOQ = 0.478 +/- 0.007 mg L-1, and Dp epsilon(600nm) = 15,900 M-1 cm(-1,) LOD = 0.143 +/- 0.002 mg L-1, LOQ = 0.478 +/- 0.007 mg L-1). The effectiveness of this colorimetric method for the selective quantification of catechol/pyrogallol-based anthocyanins has been demonstrated in the aforementioned complex real matrices and compared to LC-MS/MS analysis and pH-differential method, offering a valuable tool to characterize plant and food extracts particularly rich in zinc-coordinating anthocyanins.
查看更多>>摘要：Given the promising prospect of nanozymes system with multi-enzyme mimetic activities, it is also a challenge for designing a controllable nanostructure as multi-enzymes mimics by protein-guided strategy. Here, transferrin (Trf)-directed manganese oxide with 3D nanomorphology was developed. Trf-Mn3O4 quasi-nanocuboids (NCs) was obtained by improved conditions for biomineralization, which employing Trf as biotemplate and Mn2+ as metal source in alkaline solution. Fortunately, not only was the controllable structure discovered, but Trf-Mn3O4 NCs also showed tetra-enzyme mimic activities involving peroxidase-, ascorbic acid oxidase-, catalase- and superoxide dismutase-mimic activities. Further, the catalytic properties and steady-state kinetic of Trf-Mn3O4 NCs was explored, systematically. Moreover, we develop simple colorimetric sensor based on the peroxidase-mimic activity of Trf-Mn3O4 NCs for the detection of gallic acid (GA) with the linear range within 0.1-40 mu\M, and the limit of detection was 41.2 nM (S/N = 3). Besides, a novel fluorimetric sensor for the detection of AA based on the ascorbic acid oxidase-mimic activity was proposed with the linear range of 0.5 mu M-10 mu M (R2 = 0.9906) and 10 mu M-5 mM (R2 = 0.9927), and LOD of 0.24 mu M (S/N = 3) was obtained. Both the proposed sensors showed outstanding detection performance, accuracy and repeatability, which realized the detection of GA and AA in real sample, respectively. The as-synthesized tetra-enzymic mimics not only enriched the species of nanozymes, particularly for the nanozymes with multi-enzyme mimic activities, the proposed sensors showed promising potential applications for biosensor in complex samples.
查看更多>>摘要：In this work, we designed an ECL ratiometric biosensor with a three-stranded Y-type DNA (Y-DNA) probe and induced a hybridization chain reaction (HCR) for the highly sensitive detection of SARS-CoV-2 nucleic acid. The important component of this system is the self-assembled Y-Shaped probe based on three nucleic acids. Y1, Y2, and Y3 can be linked by complementary base pairing to Hairpin1 (H1), Hairpin2 (H2), and Ru modified DNA (Ru1), respectively. H1 and H2 can trigger the HCR reaction when activated by the SARS-CoV-2 RdRp gene and the 5' end of Ru1. The 5' end of Ru1 is modified with the Ru complex, which can produce a strong electrochemiluminescence luminescence signal at 620 nm under an applied voltage. Through the amplification of Y-DNA-induced HCR reaction, Ru1 on the electrode surface gradually increased, the ECL signal at 460 nm was gradually quenched, and the signal at 620 nm was steadily generated. The SARS-CoV-2 RdRp gene can be quantified according to the degree of decrease of ECL signal at 460 nm and the increase of ECL signal at 620 nm. Combining the two signal amplification strategies, this ratiometric ECL biosensor can accurately and efficiently detect the target gene with a detection limit of 59 aM.
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Elsevier