Zobrazení zdroje stránky Kendallmcintyre3726

Magnetic hierarchical flower-like Co3O4 spheres (Co3O4 nanoflowers) were facilely prepared via one-step surfactant-free and template-free wet chemical route at room temperature. The formation mechanism of Co3O4 nanoflowers was explored. The as-prepared Co3O4 nanoflowers exhibited excellent tetra-enzyme mimetic activities, including oxidase-like, peroxidase-like, catalase-like and superoxide dismutase (SOD)-like activity. The catalytic mechanism of the Co3O4 nanoflowers was studied in detail. The oxidase-like catalytic activity of Co3O4 nanoflowers was derived from the inherent oxygen vacancies of Co3O4, while the peroxidase-like catalytic activity originated from the •OH radical generated by hydrogen peroxide (H2O2). Only one specific enzyme mimics reaction with Co3O4 nanoflowers can be obtained by inhibiting specifically other nanozymes via varying pH, adding appropriate scavengers or selecting its specific substrate. Further, the steady-state kinetic and catalytic performance of the oxidase-, peroxidase- and catalase mimics of Co3O4 nanoflowers were studied. Based on the oxidase-like and peroxidase-like activities of Co3O4 nanoflowers, bifunctional colorimetric sensing platforms were constructed for the sensitive detection of acid phosphatase (ACP) with the linear range of 0.1-25 U L-1 and H2O2 with the linear range of 4-400 μM. Further, it is capable of detecting ACP in serum samples and H2O2 in water samples, respectively. Thus, the tetra-enzyme mimetic Co3O4 nanoflowers show broad prospects in the fields of biosensors, tumor therapy, environmental monitoring and biocatalysis.A one-step immunoassay for influenza A virus detection was developed using two different microbeads and a filter-inserted bottle. Two bead types with diameters of 15 (capture bead) and 3 (detection bead) μm were prepared to specifically detect influenza A virus. Anti-influenza A virus antibodies were coated on both bead types, whereas urease was immobilized only on the detection bead. An influenza A-positive sample could form a sandwich complex with the capture and detection beads; this complex would not pass through the filter, which had a controlled pore size. As the detection bead was used at a limiting concentration, it would be prevented from crossing the filter; thus, it would further react with the substrate urea and consequently increase the pH. An influenza A-negative sample would fail to form the sandwich complex in the presence of the capture and detection beads. Accordingly, the detection bead would pass through the filter into the urea buffer and increase the pH. The pH change in the urease reaction could be quantitatively measured by an indicator such as phenol red or using ion-selective field-effect transistor (ISFET). This one-step immunoassay was used for the detection of influenza A virus in real samples. The receiver operating characteristic (ROC) plot analysis showed an area under the curve (AUC) value of 0.931; the sensitivity and specificity of the assay was 80% and 90%, respectively, at a cutoff value of 0.9986. These results demonstrate that the one-step immunoassay could increase the sensitivity of influenza A virus detection in real samples.Biosensing platforms for detecting and quantifying biomarkers have played an important role in the past decade. Among them, platforms based on magnetoresistance (MR) sensing technology are attractive. The resistance value of the material changes with the externally applied magnetic field is the core mechanism of MR sensing technology. A typical MR-based sensor has the characteristics of cost-effective, simple operation, high compactness, and high sensitivity. Moreover, using magnetic nanoparticles (MNPs) as labels, MR-based sensors have the ability to overcome the high background noise of complex samples, so they are particularly suitable for point-of-care testing (POCT). However, the problem still exists. How to obtain high-throughput, that is, multiple detections of biomarkers in MR-based sensors, thereby improving detection efficiency and reducing the burden on patients is an important issue in future work. This paper reviews three MR-based detection technologies for the detection of biomarkers, i.e., anisotropic magnetoresistance (AMR), giant magnetoresistance (GMR), and tunneling magnetoresistance (TMR). Based on these three common technologies, different typical applications that include biomedical diagnosis, food safety, and environmental monitoring are presented. Furthermore, the existing MR-based detection method is better expanded to make it more in line with present detection needs by combining different advanced technologies including microfluidics, Microelectromechanical systems (MEMS), and Immunochromatographic test strips (ICTS). And then, a brief discussion of current challenges and perspectives of MR-based sensors are pointed out.Enzyme-linked immunosorbent assays are currently the most popular methods to quantify gluten in foods. Unfortunately, the antibodies used as specific receptors in such methods are not compatible with the usual solvents for the extraction of gluten proteins. In consequence, commercial tests require a high dilution of the sample after the extraction, increasing the limit of quantification and decreasing convenience. In this work, we have rationally truncated an aptamer capable of recognizing gliadin in a deep eutectic solvent (DES). The truncated aptamer is a 19-nucleotides-long DNA that minimizes self-hybridization, allowing the development of an electrochemical sandwich-based sensor for the quantification of gluten in the DES ethaline. [https://www.selleckchem.com/products/epacadostat-incb024360.html Epacadostat] The sensor incorporates two identical biotin-labeled truncated aptamers, one of which is immobilized on a carbon screen-printed electrode and the other reports the binding of gliadin after incubation in streptavidin-peroxidase. This sensor can detect gliadin in DES, with a dynamic range between 1 and 100 μg/L and an intra-assay coefficient of variation of 11%. This analytical performance allows the quantification of 20 μg of gluten/kg of food when 1 g of food is extracted with 10 mL of ethaline. We demonstrate the ability of this method to achieve the measurement of gluten in food samples, after the extraction with pure ethaline. The assay is useful for the analysis of residual gluten levels in foods, thus facilitating the evaluation of any potential health risk associated with the consumption of such food by people with celiac disease or other gluten-related disorders.