Fluorescence lifetime imaging microscopy using near-infrared contrast agents

R. Nothdurft, P. Sarder, S. Bloch, J. Culver, S. Achilefu

Research output: Contribution to journalArticlepeer-review

19 Scopus citations


Although single-photon fluorescence lifetime imaging microscopy (FLIM) is widely used to image molecular processes using a wide range of excitation wavelengths, the captured emission of this technique is confined to the visible spectrum. Here, we explore the feasibility of utilizing near-infrared (NIR) fluorescent molecular probes with emission >700 nm for FLIM of live cells. The confocal microscope is equipped with a 785 nm laser diode, a red-enhanced photomultiplier tube, and a time-correlated single photon counting card. We demonstrate that our system reports the lifetime distributions of NIR fluorescent dyes, cypate and DTTCI, in cells. In cells labelled separately or jointly with these dyes, NIR FLIM successfully distinguishes their lifetimes, providing a method to sort different cell populations. In addition, lifetime distributions of cells co-incubated with these dyes allow estimate of the dyes' relative concentrations in complex cellular microenvironments. With the heightened interest in fluorescence lifetime-based small animal imaging using NIR fluorophores, this technique further serves as a bridge between in vitro spectroscopic characterization of new fluorophore lifetimes and in vivo tissue imaging.

Original languageEnglish
Pages (from-to)202-207
Number of pages6
JournalJournal of Microscopy
Issue number2
StatePublished - Aug 2012


  • Fluorescence lifetime imaging microscopy
  • Live cell imaging
  • Near infrared fluorescent molecular probes


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