Abstract
Recently, much attention has been devoted to food-related health issues. In particular, food-poisoning bacteria are becoming a serious threat to human health. So far, techniques used to detect these bacteria are time-consuming and laborious. To overcome these challenges, a biosensor with a simple platform was developed to detectSalmonella typhimurium. The colorimetric strategy is attractive because it enables simple and rapid sensing with the naked eyes. We used magnetic nanoparticles (MNPs), specific aptamers, and a colorimetric substrate, 3,3′,5,5′-tetramethylbenzidine (TMB) in the presence of H2O2. Because MNPs display enzyme-like activities, they can undergo color changes with the help of a colorimetric substrate. In this system, MNPs were first incubated with aptamers that specifically interact with theSalmonellaspecies, reducing the peroxidase activity of the MNPs via DNA-mediated shielding of catalytic activity. After the addition ofSalmonellacells to the solution, specific aptamers on the MNPs interact with theSalmonella, consequently enhancing the peroxidase activity of the MNPs. Considering their low cost, easy separation, and stable activity, MNPs could be applied to various detection systems.
Highlights
Food-poisoning bacteria have been a serious threat to human health for the past years
magnetic nanoparticles (MNPs) were prepared by the coprecipitation method with sonication
The peroxidase-like activities of Fe3O4 MNPs increased and resulted in small spherical particles that were below 20 nm in diameter (Figures 1(a) and 1(b))
Summary
Food-poisoning bacteria have been a serious threat to human health for the past years. Nanomaterials conjugated with antibodies have a unique possibility in detecting bacteria or other molecules These methods have several limitations that depend on experimental conditions (e.g., salt concentration, pH, and temperature) and are subjected to complicated steps during the preparation and conjugation of antibodies on the nanoparticles [10]. Aptamers that interact with outer membrane protein on the surface of S. typhimurium were used [14, 15] As another well-known materials, MNPs exhibit catalytic stability, ease to separation, and chemical inertness. Once H2O2 molecules are adsorbed onto the surface of MNPs, Fe2+ and Fe3+ in the aMnNd POs2c−a∙t/aHlyOze2∙th[1e8d].isBaescsaeumsbeloyfotfhHe 2hOig2htooxriaddiizcianlgs like ∙OH ability of radical, it mediates oxidation of TMB This reaction produces a blue-colored product, which enables colorimetric detection with naked eyes. The development of methods for a fast and stable detection of bacteria is of great significance in avoiding and controlling Salmonella pathogens
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