tecan Infinite 200 PRO Instructions For Use Manual page 21

B) Fluorescence Resonance Energy Transfer (FRET)
C) Time Resolved Fluorescence (TRF)
2016-04
Some microplate applications utilize a sophisticated dual labeling strategy. The
FRET effect enables you to measure how many of two differently labeled
compounds are in close proximity. This makes it suitable for binding studies.
Basically, FRET is a fluorescence intensity measurement of one of the two
fluorescent labels (acceptor). However, the acceptor is not susceptible to the
excitation wavelength of the light source being used. Instead, the acceptor may
receive excitation energy from the other fluorescent label (donor), if both are
spatially close together. As a prerequisite, the excitation wavelength has to apply
to the donor. Secondly, the emission spectrum of the donor has to overlap the
excitation spectrum of the acceptor (resonance condition). Nevertheless, the
transfer of excitation energy from donor to the acceptor is radiation free.
Some FRET-based applications utilize suitable pairs from the fluorescent protein
family, like GFP/YFP (Green/Yellow Fluorescent Protein, (ref. Using GFP in
FRET-based applications by Brian A. Pollok and Roger Heim – trends in Cell
Biology [Vol.9] February 1999). Overview is given in the Review Article –
Application of Fluorescence Resonance Energy Transfer in the Clinical
Laboratory: Routine and Research by J. Szöllösi, et al. in Cytometry 34, page
159-179 (1998).
Other FRET-based applications take advantage from using TRF labels as the
donor. For example see, High Throughput Screening – Marcel Dekker Inc.
1997, New York, Basel, Hong Kong, section 19 Homogeneous, Time-Resolved
Fluorescence Method for Drug Discovery by Alfred J. Kolb, et al.
TRF applies to a class of fluorescent labels (chelates of lanthanides like
Europium, [ref. Europium and Samarium in Time-Resolved
Fluoroimmunoassays by T. Stâhlberg, et. al. - American Laboratory, December
1993 page 15]), some of them having fluorescence lifetimes in excess of 100
microseconds. The Infinite 200 PRO uses a Flash lamp light source with flash
duration much shorter than fluorescence lifetime of these species. This offers the
opportunity to measure fluorescence emission at some time, when stray light and
prompt fluorescence have already vanished (Lag Time). Thus, background can
be significantly lowered while sensitivity is improved.
The benefits of TRF consequently apply to assays using multiple labels with
different fluorescence lifetimes.
IFU for Infinite 200 PRO No. 30052730
2. General Description
Rev. No. 1.6 21