Nanostructures plasmoniques dynamiques assemblées sur ADN

Laurent Lermusiaux 1, 2
2 POM - Physique des Ondes pour la Médecine et la Biologie
Institut Langevin ondes et images, INSERM - Institut National de la Santé et de la Recherche Médicale : U979
Abstract : We demonstrate how gold nanoparticle dimers assembled around a single DNA template exhibiting a specific recognition site, provide a macroscopic optical signal depending on their chemical environment. Electrophoresis enables us to produce purified suspensions of gold nanoparticle dimers, with particle diameters ranging from 8 to 60 nm, with different surface chemistries and sample purities as high as 90%. The DNA template features a hairpin loop in order to switch its shape reversibly when binding a target DNA strand. Interparticle distances are estimated using cryo-electron microscopy and indicate a reversible change of the surface-to-surface distance by a factor of 3 in the case of 8 nm diameter gold particles. In order to translate the dynamic switching of a single DNA scaffold in a measurable optical signal, we study the scattering cross-sections of single 40 nm or 60 nm diameter gold nanoparticle dimers, in microfluidic conditions. We are able to progressively decrease the interparticle distance, at the nanometer scale, by increasing the local salt concentration. This deformation results in a spectral shift of the resonance (up to 100 nm) corresponding to a decrease of the interparticle distance from 20 to 1 nm. Moreover, the good correlation between the spectral responses of individual dimers, estimated using a spectrometer or a CCD color camera, enables us to demonstrate a wide-field low-cost detection method of the nanometric deformation of these nanostructures. Using amphiphilic ligands enables us to optimize the colloidal stability of gold nanoparticle dimers in order to minimize their sensitivity to the local ionic strength and temperature changes.
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  • HAL Id : tel-01121934, version 1

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Laurent Lermusiaux. Nanostructures plasmoniques dynamiques assemblées sur ADN. Physique des plasmas [physics.plasm-ph]. Université Pierre et Marie Curie - Paris VI, 2015. Français. ⟨NNT : 2015PA066007⟩. ⟨tel-01121934⟩

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