Elimination of autofluorescence in fluorescence correlation spectroscopy using the AzaDiOxaTriAngulenium (ADOTA) fluorophore in combination with time-correlated single-photon counting (TCSPC)

Ryan M. Rich, Mark Mummert, Zygmunt Gryczynski, Julian Borejdo, Thomas Just Sorensen, Bow Laursen, Zeno Foldes-Papp, Ignacy Gryczynski, Rafal Fudala

Research output: Contribution to journalArticlepeer-review

25 Scopus citations

Abstract

Fluorescence correlation spectroscopy (FCS) is a frequently applied technique that allows for the precise and sensitive analysis of molecular diffusion and interactions. However, the potential of FCS for in vitro or ex vivo studies has not been fully realized due in part to artifacts originating from autofluorescence (fluorescence of inherent components and fixative-induced fluorescence). Here, we propose the azadioxatriangulenium (ADOTA) dye as a solution to this problem. The lifetime of the ADOTA probe, about 19.4 ns, is much longer than most components of autofluorescence. Thus, it can be easily separated by time-correlated single-photon counting methods. Here, we demonstrate the suppression of autofluorescence in FCS using ADOTAlabeled hyaluronan macromolecules (HAs) with Rhodamine 123 added to simulate diffusing fluorescent background components. The emission spectrum and decay rate of Rhodamine 123 overlap with the usual sources of autofluorescence, and its diffusion behavior is well known. We show that the contributions from Rhodamine 123 can be eliminated by time gating or by fluorescence lifetime correlation spectroscopy (FLCS). While the pairing of ADOTA and time gating is an effective strategy for the removal of autofluorescence from fluorescence imaging, the loss of photons leads to erroneous concentration values with FCS. On the other hand, FLCS eliminates autofluorescence without such errors. We then show that both time gating and FLCS may be used successfully with ADOTA-labeled HA to detect the presence of hyaluronidase, the overexpression of which has been observed in many types of cancer.

Original languageEnglish
Pages (from-to)4887-4894
Number of pages8
JournalAnalytical and bioanalytical chemistry
Volume405
Issue number14
DOIs
StatePublished - May 2013

Keywords

  • Fluorescence
  • Fluorescence correlation spectroscopy
  • Hyaluronan
  • Time-correlated single-photon counting

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