title: Widefield spectral monitoring of nanometer distance changes in DNA-templated plasmon rulers.
abstract: The nanometer-scale sensitivity of electromagnetic plasmon coupling allows the translation of minute morphological changes in nanostructures into macroscopic optical signals. We demonstrate here a widefield spectral analysis of 40 nm diameter gold nanoparticle (AuNP) dimers, linked by a short DNA double strand, using a low-cost color CCD camera and allowing a quantitative estimation of interparticle distances in a 3-20 nm range. This analysis can be extended to lower spacings and a parallel monitoring of dimer orientations by performing a simple polarization analysis. Our measurement approach is calibrated against confocal scattering spectroscopy using AuNP dimers that are distorted from a stretched geometry at low ionic strength to touching particles at high salt concentrations. We then apply it to identify dimers featuring two different conformations of the same DNA template and discuss the parallel colorimetric sensing of short sequence-specific DNA single strands using dynamic plasmon rulers.
authors.affiliation: ESPCI ParisTech, PSL Research University, CNRS, INSERM, Institut Langevin, 1 rue Jussieu, F-75005 Paris, France.
authors.forename: Laurent
authors.initials: L
authors.lastname: Lermusiaux
authors.forename: Vincent
authors.initials: V
authors.lastname: Maillard
authors.forename: Sébastien
authors.initials: S
authors.lastname: Bidault
mesh_terms: D001483:Base Sequence; D004247:DNA / Q000737:chemistry* / Q000235:genetics; D019281:Dimerization; D006046:Gold / Q000737:chemistry; D055029:Inverted Repeat Sequences; D053768:Metal Nanoparticles / Q000737:chemistry; D036103:Nanotechnology / Q000379:methods*; D055620:Optical Phenomena; D013057:Spectrum Analysis / Q000379:methods*
chemical_list: D006046:Gold; D004247:DNA
keywords: DNA self-assembly; colorimetric sensing; darkfield microscopy; dynamic nanostructures; plasmon ruler; widefield spectroscopy