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

Methodologies for “Wiring” Redox Proteins/Enzymes to Electrode Surfaces

The immobilization of redox proteins or enzymes onto conductive surfaces has application in the analysis of biological processes, the fabrication of biosensors, and in the development of green technologies and biochemical synthetic approaches. This review evaluates the methods through which redox proteins can be attached to electrode surfaces in a “wired” configuration, that is, one that facilitates direct electron transfer. The feasibility of simple electroactive adsorption onto a range of electrode surfaces is illustrated, with a highlight on the recent advances that have been achieved in biotechnological device construction using carbon materials and metal oxides. The covalent crosslinking strategies commonly used for the modification and biofunctionalization of electrode surfaces are also evaluated. Recent innovations in harnessing chemical biology methods for electrically wiring redox biology to surfaces are emphasized

Carbon nanotubes architectures in electroanalysis

AbstractElectroanalysis is one of the promising analysis methods for various aspects. Carbon nanotubes (CNTs), a novel carbon form, has been also exploited as an electrode material in electroanalysis as a result of its extraordinary electronic, chemical and mechanical properties. In addition, CNTs is also stable and robustness and is compatible with various chemical and biological species, hence the nanotubes’ abilities recognized to various analyzes associated to those species. However, not only the electrode materials can influence the electrode electrochemical properties, but also the electrode orientation or architecture does. This paper, therefore, reviews various carbon nanotubes (CNTs) oriented architectures practically employed in electroanalysis for different purposes. Those include 1) CNTs casting films and CNTs polymer composites, (2) CNTs paste and polymer composites, (3) as grown CNTs and individual CNT and (4) CNTs arrays

Beneficial effects of commercial Assam green tea infusion on the microbial growth and oxidative stability of cooked beef

Natural preservatives having the great antioxidant and antimicrobial activity have been utilized in the food industry for many years. In the present study, the effect of of two brands of commercial Assam green tea infusion (represented by A and B) and 0.02% BHA/BHT on microbial growth, anti-lipid oxidation and color change were investigated in cooked beef. The green tea concentration has influenced to the results. It was found that A and B at the concentration of 250 mg/mL significantly reduced the population of Staphylococcus aureus, Listeria monocytogenes, Salmonella typhimurium and E. coli in the cooked beef to an undetectable level within 2 days of storage at 4°C. A and B also exhibited higher anti-lipid oxidation activity compared to 0.02% BHA/BHT, and control. Assam green tea infusions in cooked beef significantly increased δ L* value and decreased δ a* and δ b* value (p ≤ 0.05). These indicate that Assam green tea infusion might be a potential candidate as a natural preservative for beef and other types of food