Label-free as-grown double wall carbon nanotubes bundles for Salmonella typhimurium immunoassay

Background: A label-free immunosensor from as-grown double wall carbon nanotubes (DW) bundles was developed for detecting Salmonella typhimurium. The immunosensor was fabricated by using the as-grown DW bundles as an electrode material with an anti-Salmonella impregnated on the surface. The immunosensor was electrochemically characterized by cyclic voltammetry. The working potential (100, 200, 300 and 400 mV vs. Ag/AgCl) and the anti-Salmonella concentration (10, 25, 50, 75, and 100 μg/mL) at the electrode were subsequently optimized. Then, chronoamperometry was used with the optimum potential of 100 mV vs. Ag/AgCl) and the optimum impregnated anti-Salmonella of 10 μg/mL to detect S. typhimurium cells (0-109 CFU/mL). Results: The DW immunosensor exhibited a detection range of 102 to 107 CFU/mL for the bacteria with a limit of detection of 8.9 CFU/mL according to the IUPAC recommendation. The electrode also showed specificity to S. typhimurium but no current response to Escherichia coli. Conclusions: These findings suggest that the use of a label-free DW immunosensor is promising for detecting S. typhimurium

Lateral flow assay modified with time-delay wax barriers as a sensitivity and signal enhancement strategy

Altres ajuts: this work is also funded by the CERCA Program/Generalitat de CatalunyaThe ease of use, low cost and quick operation of lateral flow assays (LFA) have made them some of the most common point of care biosensors in a variety of fields. However, their generally low sensitivity has limited their use for more challenging applications, where the detection of low analytic concentrations is required. Here we propose the use of soluble wax barriers to selectively and temporarily accumulate the target and label nanoparticles on top of the test line (TL). This extended internal incubation step promotes the formation of the immune-complex, generating a 51.7-fold sensitivity enhancement, considering the limit of quantification, and up to 96% signal enhancement compared to the conventional LFA for Human IgG (H-IgG) detection

Calculating steady-state currents of planar interdigitated electrode arrays in shallow cells

<p>Calculation and plots of steady-state voltammograms, currents, current densities and concentration profiles at shallow electrochemical cells with embedded interdigitated electrode arrays.</p&gt

Utilising solution dispersed platinum nanoparticles to direct the growth of electrodeposited platinum nanostructures and its influence on the electrocatalytic oxidation of small organic molecules

Highlights - The presence of Pt nanoparticles in solution influences the electrodeposition of Pt. - Nanostructured Pt with different exposed crystal facets are formed in the presence of Pt nanoparticles. - Enhanced electrocatalytic activity is found for nanostructures created using Pt nanoparticles in solution. Abstract The electrodeposition of platinum nanostructures on glassy carbon electrodes in the absence and presence of platinum nanoparticles in the electrolyte is reported. It is found that the presence of platinum nanoparticles has a significant influence of the morphology of the platinum electrodeposited onto the electrode surface. Even though the morphology of the materials is affected, the overall surface area is similar. The electrochemical behaviour of the platinum nanostructures is investigated in 1 M H2SO4 where distinct differences are observed in the exposed surface sites for platinum electrodeposited in the presence of nanoparticles. The influence of these surface sites is then studied for a variety of electrocatalytic reactions such as methanol and ethylene glycol oxidation and the hydrogen evolution reaction. In the case of organic molecule oxidation reactions, the platinum structures created using platinum nanoparticles in the electrodeposition solution exhibited earlier onset potentials and increased current densities compared to those that were electrodeposited in their absence