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Design of plasmonic nanoparticles and their use for biotoxin immunosensing

Abstract : Staphylococcal enterotoxin A (SEA) produced by some Staphylococcus aureus strains is a major cause of food poising and especially represents the second cause of foodborne diseases in France. Plasmonic nanoparticles with unique optical properties are widely applied as transducers in biosensing devices owing to the Localized Surface Plasmon Resonance (LSPR) phenomenon. The objective of this work was to develop biosensors based on plasmonic nanoparticles from which SEA detection could be achieved by naked-eye readout. Two strategies were implemented. The first strategy was based on the extremely high extinction coefficient of gold nanoparticles (AuNPs). Anti-SEA antibody (Ab)-conjugated AuNPs were used as reporters in a solid-phase, sandwich-type, colorimetric immunosensor. The sensor was successfully applied to the detection of SEA in buffer and spiked milk. As low as 1 ng SEA could be visualized by naked-eye readout. The second strategy relied on both the sensitivity of the LSPR band of plasmonic nanoparticles to small local refractive index change and the ability of humans to visualize color changes in the 500 nm region. For this purpose, core-shell gold silver nanoparticles (Au@AgNPs) with LSPR band at 500 nm were successfully synthesized. Attachment of Ab to Au@AgNPs resulted in a red shift of LPSR band and a visual color change of colloidal solution from orange to red. Yet, the red shift of LSPR band was very important and no visible change of color was observed by naked-eye upon subsequent addition of SEA.
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  • HAL Id : tel-02890626, version 1

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Lu Zhang. Design of plasmonic nanoparticles and their use for biotoxin immunosensing. Organic chemistry. Sorbonne Université; Nanyang Technological University, 2018. English. ⟨NNT : 2018SORUS439⟩. ⟨tel-02890626⟩

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