Research Article

Nano Research

, Volume 2, Issue 3, pp 220-234

Open Access This content is freely available online to anyone, anywhere at any time.

Fluorescent superlattices of gold nanoparticles: A new class of functional materials

  • Edakkattuparambil Sidharth ShibuAffiliated withDST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology
  • , Madathumpady Abubaker Habeeb MuhammedAffiliated withDST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology
  • , Keisaku KimuraAffiliated withGraduate School of Material Science, University of Hyogo
  • , Thalappil PradeepAffiliated withDST Unit on Nanoscience (DST UNS), Department of Chemistry and Sophisticated Analytical Instrument Facility, Indian Institute of Technology Email author 

Abstract

Fluorescent three-dimensional (3-D) superlattices of dansyl glutathione protected gold nanoparticles, with potential applications in molecular detection, have been synthesized at an air/water interface by controlling the pH of the nanoparticle suspension. The number of fluorophores per nanoparticle was calculated to be ∼127. Morphologies of the superlattice crystals were examined using scanning electron microscopy (SEM). Most of the crystals observed were triangular in shape. High-resolution transmission electron microscopy (HRTEM) and small angle X-ray scattering (SAXS) were used to study the packing of nanoparticles in these crystals. Both these studies showed that the nanoparticles were arranged in a face-centered cubic (fcc) pattern with a particle-particle distance (center-center) of ∼10.5 nm. Evolution of the crystal morphologies with time was also examined. The fluorescence properties of these triangles were studied using confocal fluorescence imaging and confocal Raman mapping, which were in good agreement with the morphologies observed by SEM. The superlattice exhibits near-infrared (NIR) absorption in the range 1100–2500 nm. Easy synthesis of such functional nanoparticle-based solids makes it possible to use them in novel applications. We utilized the fluorescence of dansyl glutathione gold superlattice crystals for the selective detection of bovine serum albumin (BSA), the major protein constituent of blood plasma, based on the selective binding of the naphthalene ring of the dansyl moiety with site I of BSA.

http://static-content.springer.com/image/art%3A10.1007%2Fs12274-009-9020-0/MediaObjects/12274_2009_9020_Fig1_HTML.gif

Keywords

Periodic self-assembly dansyl glutathione fluorescent superlattice confocal fluorescence imaging selective binding