查看更多>>摘要：A lab-on-a-tube biosensor was established to rapidly, sensitively and automatically detect foodborne bacteria through a rotatable Halbach magnet to form and rotate magnetic nanobead (MNB) chains for specific isolation of target bacteria, gold@platinum nanocatalysts (Au@PtNCs) to label target bacteria for efficient amplification of detection signal and Raspberry Pi App to collect and analyze the image of catalysate. First, the glass tube was successively preloaded with the mixture of MNBs, sample and Au@PtNCs, the washing buffer (skim milk) and the substrate (hydrogen peroxide-3,30,5,50-tetramethylbenzidine), and they were separated by air gaps. After the tube was placed on the biosensor, the MNB chains were stably formed and continuously rotated using the Halbach magnet and the mixture was moved back and forth using a programmable peristaltic pump, thus making the formation of MNB-bacteria-Au@PtNCs complexes. After the washing buffer was moved to wash the complexes, the substrate was then moved to resuspend the complexes, resulting in the catalytic reaction that changed the color of the substrate. Finally, the catalysate was moved to the designated area, the image of which was analyzed by the Raspberry Pi App to quantitatively determine the concentration of bacteria in the samples. This biosensor was able to detect Salmonella in spiked chicken samples in 1 h with lower detection limit of 8 CFU/50 mu L and a recovery from 88.96% to 99.74%. This biosensor based on a single tube is very promising to automatically detect foodborne bacteria due to its low cost, high integration and simple operation.
查看更多>>摘要：Recombinant protein biopharmaceuticals comprise a significant portion of the current drug development landscape. The glycosylation profile of these proteins is a key quality parameter as it can affect their safety, efficacy, and stability. However, glycan analysis is challenging because of the complexity of their structures. To overcome this challenge in achieving accurate glycan identification, cross-identification of N-Glycans by CE-LIF method using two capillary coatings and three labeling dyes was developed in this work. This work explored whether complementary separation capabilities can be achieved using homemade polyvinyl alcohol (PVA) coating and commercial Guarant (TM) (Guarant) coating in the analysis of N-glycans. Similar separation profiles were observed using the two capillary coatings, and hence the N-glycan GU databases generated by these coatings were comparable and complementary. The performance of cross-validation by labeling with three fluorescent dyes indicated that low covariance of APTS and Turquoise (TM) labeling can be obtained, and hence these two labeling mechanisms provided better accuracy for the identification of glycans. Superior reproducibility with RSDs less than 1% for all target glycan standards was achieved by the internal standards (IS) method using maltodextrin ladders as additives in the separation buffer. The developed CE-LIF analysis method was applied to the identification of N-glycans in IgG samples.
Purohit, P.Fortes, F. J.Malegiannaki, I.Jaime-Fernandez, L....
9页
查看更多>>摘要：In the present paper, confined dry Cu nanoaerosols of controlled particle size are inspected under a time-resolved LIBS scheme to explore the effect of laser-particulate matter interaction upon the detection capability of airborne nanoparticulate material. Optically catapulted streams probed showed linear intensity vs mass correlation and similar signal stability which is linked to the seeding effect caused by smaller particles yielding hotter, albeit shorter plasmas. Seeding effect is demonstrated by hyperspectral time-resolved aerosol inspection, which exposes both, the interaction between multiple plasma nuclei and the discrete nature of the laser-particle interaction. Observed population/exhaustion cycles at the focal volume of the inspection laser explained the uncertainty values characteristic of LIBS inspection of aerosols. A thorough inspection of the emission in time evidenced a significantly different evolution of the intensity profile for commonly monitored Cu lines owed not only to the nature of the monitored transit and pulse energy, but also to particle size. These results suggest that the experimental settings for quantitative ultrafine aerosol inspection need to be tuned according to the target particle size and the particle density of the aerosol as seeding effects facilitates signal saturation, therefore this effect simultaneously contributes to and detracts from the analytical performance of LIBS on nanometric aerosols.
Soares, Juliana C.Soares, Andrey C.Angelim, Monara Kaelle S. C.Proenca-Modena, Jose Luiz...
7页
查看更多>>摘要：Mass testing for the diagnostics of COVID-19 has been hampered in many countries owing to the high cost of the methodologies to detect genetic material of SARS-CoV-2. In this paper, we report on a low-cost immunosensor capable of detecting the spike protein of SARS-CoV-2, including in samples of inactivated virus. Detection is performed with electrical impedance spectroscopy using an immunosensor that contains a monolayer film of carboxymethyl chitosan as matrix, coated with an active layer of antibodies specific to the spike protein. In addition to a low limit of detection of 0.179 fg/mL within an almost linear behavior from 10-20 g/mL to 10-14 g/ mL, the immunosensor was highly selective. For the samples with the spike protein could be distinguished in multidimensional projection plots from samples with other biomarkers and analytes that could be interfering species for healthy and infected patients. The excellent analytical performance of the immunosensors was validated with the distinction between control samples and those containing inactivated SARS-CoV-2 at different concentrations. The mechanism behind the immunosensor performance is the specific antibody-protein interaction, as confirmed with the changes induced in C-H stretching and protein bands in polarization-modulated infrared reflection absorption spectra (PM-IRRAS). Because impedance spectroscopy measurements can be made with low-cost portable instruments, the immunosensor proposed here can be applied in point-of-care diagnostics for mass testing even in places with limited resources.
查看更多>>摘要：Chiral metal-organic frameworks (CMOFs) served as chiral stationary phases (CSPs) show great potential in enantioseparation field. However, their performance improvement are still hindered by the difficult column packed and high back pressure due to the irregular morphology and broad size scope of CMOF particles. Here, the size and morphology of achiral Co-MOF-74 were effectively adjusted by controlling the synthetic route, temperature, the ratio of reactants and the amount of 2-methylimidazole (2-MI) at first. As a result, the uniformly spherical crystals in size of about 5 mu m with good dispersion were obtained. Subsequently, a simple, green post synthetic modification strategy was proposed for the fabrication of L-tyrosine functionalized Co-MOF-74, namely Co-MOF-74-L-Tyr in H2O by incorporating L-tyrosine into the parent framework of Co-MOF-74 to construct chiral microenvironment. The homochiral Co-MOF-74-L-Tyr CSP gave superior enantioseparation performance for the eight chiral drugs and drug intermediates, such as nitrendipine, nimodipine, benzoin, 2,2'-furoin and bi-2-naphthol to the commercial columns under normal phase condition. The good repeatability and stability of this CSP was verified by the replicate enantioseparation for nimodipine and flavanone. Furthermore, the CoMOF-74-L-Tyr packed column was successfully applied to detect the product N-1-(1-naphthyl)ethyltosylamide (HR-8) in the asymmetric reductive amination reaction. The size/morphology-controlled synthesis coupled with the green post-synthetic modification approach paves the way to fabricate target chiral MOFs with pre-designed functional groups, which is an effective complement for the preparation of CSPs in chiral chromatography.
查看更多>>摘要：Circulating tumor cells (CTCs) are cancer cells that shed from the primary tumor and then enter the circulatory system, a small part of which may evolve into metastatic cancer under appropriate microenvironment conditions. The detection of CTCs is a truly noninvasive, dynamic monitor for disease changes, which has considerable clinical implications in the selection of targeted drugs. However, their inherent rarity and heterogeneity pose significant challenges to their isolation and detection. Even the "gold standard", CellSearchTM, suffers from high expenses, low capture efficiency, and the consumption of time. With the advancement of CTCs analysis technologies in recent years, the yield and efficiency of CTCs enrichment have gradually been improved, as well as detection sensitivity. In this review, the isolation and detection strategies of CTCs have been completely described and the potential directions for future research and development have also been highlighted through analyzing the challenges faced by current strategies.
查看更多>>摘要：An easy-to-use and efficient approach for the catalytic pyrolysis of hydrocarbon gas here is proposed and tested, which allowed the precise measurement of delta H-2. This method requires the reaction tube filled with twisted chromium wire, establishing a gas chromatography-Chromium wire/high temperature conversion-isotope ratio mass spectrometer (GC-Cr/HTC-IRMS) system. The approach described here has many remarkable advantages over other techniques. In comparison to traditional carbon-coating pyrolysis technique, this proposed method greatly reduces the pyrolysis temperature of the hydrocarbon gas, especially methane, with temperatures reduced from 1450 to 1250 degrees C, while still ensuring excellent analytical precision. Therefore, hydrogen isotope analysis of natural gas can be carried out at a lower cracking temperature for a longer time, with the advantage of increasing the service life of the HTC furnace. Meanwhile, no pretreatment or activation is required while putting the Cr/HTC system to use. Further, the accuracy of delta H-2 values obtained using this new method is better than using the traditional method. Our experiments demonstrate that the test errors of this novel method and the conventional method are within +/- 5.5 parts per thousand and +/- 6.5 parts per thousand, respectively.
NSTL
Elsevier