Nanoparticle energy transfer on the cell surface

Research output: Contribution to journalArticle

26 Citations (Scopus)

Abstract

Membrane topology of receptors plays an important role in shaping transmembrane signalling of cells. Among the methods used for characterizing receptor clusters, fluorescence resonance energy transfer between a donor and acceptor fluorophore plays a unique role based on its capability of detecting molecular level (2-10 nm) proximities of receptors in physiological conditions. Recent development of biotechnology has made possible the usage of colloidal gold particles in a large size range for specific labelling of cells for the purposes of electron microscopy. However, by combining metal and fluorophore labelling of cells, the versatility of metal-fluorophore interactions opens the way for new applications by detecting the presence of the metal particles by the methods of fluorescence spectroscopy. An outstanding feature of the metal nanoparticle-fluorophore interaction is that the metal particle can enhance spontaneous emission of the fluorophore in a distance-dependent fashion, in an interaction range esentially determined by the size of the nanoparticle. In our work enhanced fluorescence of rhodamine and cyanine dyes was observed in the vicinity of immunogold nanoparticles on the surface of JY cells in a flow cytometer. The dyes and the immunogold were targetted to the cell surface receptors MHCI, MHCII, transferrin receptor and CD45 by monoclonal antibodies. The fluorescence enhancement was sensitive to the wavelength of the exciting light, the size and amount of surface bound gold beads, as well as the fluorophore-nanoparticle distance. The intensity of 90° scattering of the incident light beam was enhanced by the immunogold in a concentration and size-dependent fashion. The 90° light scattering varied with the wavelength of the incident light in a manner characteristic to gold nanoparticles of the applied sizes. A reduction in photobleaching time constant of the cyanine dye was observed in the vicinity of gold particles in a digital imaging microscope. Modulations of 90° light scattering intensity and photobleaching time constant indicate the role of the local field in the fluorescence enhancement. A mathematical simulation based on the electrodynamic theory of fluorescence enhancement showed a consistency between the measured enhancement values, the inter-epitope distances and the quantum yields. The feasibility of realizing proximity sensors operating at distance ranges larger than that of the conventional Förster transfer is demonstrated on the surface of living cells.

Original languageEnglish
Pages (from-to)236-253
Number of pages18
JournalJournal of Molecular Recognition
Volume18
Issue number3
DOIs
Publication statusPublished - May 1 2005

Keywords

  • 90° light scattering
  • CD45
  • Fluorescence energy transfer
  • MHCI and MHCII antigens
  • Photobleaching
  • Plasmon resonance
  • Receptor clustering
  • Transferrin receptor

ASJC Scopus subject areas

  • Structural Biology
  • Molecular Biology

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