|
Wallac 1234 Delfia
High sensitivity
Multi-label assays possible
Unbeatable sensitivity, dynamic
range, and
consistency of results
More than 1000 scientific references
Monitor induction of up to three
surface
antigens in
one well
Ready made protocols with
commercially
available
receptors
The DELFIA
1234 fluorometer detects fluorescence from europium, samarium and
terbium lanthanide chelates. It measures samples directly from the
plate and allows measurement over a very wide dynamic range down to
extremely low concentrations. Measurement time is only 1 second per
sample or about 3 minutes for a whole plate.
There is a built-in
40-character alphanumeric display, or the instrument may be controlled
by a PC running MultiCalc software. A bar-code reader allows automatic
call-up of protocol and worklists.
Time-resolved
fluorometry is the exciting alternative to the use of radionuclides in
label assays. The technology allows simple, robust assays, and above
all, sensitivity better than that of any other non- radioisotopic
method. The high sensitivity of time- resolved fluorometry stems from
the unique fluorescence properties of lanthanide chelates which allows
their clear distinction from background on the basis of time as well
as on fluorescence wavelength. Wallac DELFIAź products include a wide
selection of reagents kits for researchers and for clinicians working
in fields such as endocrinology, oncology, as well as in haematology.
In addition to ready-to-use kits, Wallac- now
Perkin Elmer Life Science also supplies - labelling reagents,
antibody coated plates, universal reagents, etc. which make it easy to
develop time-resolved fluorometry assays for less commonly measured
analytes
Why time-resolved fluorometry bears
no comparison with prompt fluorescence measurement
1. New types of fluorophore - offering
multilabel possibilities
Europium chelates have far wider Stokes
shift than commonly used conventional fluorophores. This means that
the wavelength of the emitted light is as much as 200- 300 nm longer
than that of the excitation light used. The emission wavelength is
also unique for each lanthanide fluorophore. Because there is
virtually no overlap between the emission spectra, the technology is
well suited for multilabel assay designs. Dual label TRF assays are in
routine use in clinical laboratories, while triple and quadruple
assays have been developed for research use.
2. Measurement using time-resolution
Lanthanide chelates' fluorescence lasts
20 -35 times longer than fluorescence from a conventional fluorophore.
Time resolved measurement starts only after fluorescence from
any conventional substance would be undetectable.
Background on time resolved fluorescence
Efforts by
biopharmaceutical and academic laboratories to screen very large
synthetic or natural compound libraries have inspired development of
new and diverse forms of fluorescence technology suitable for
ultrafast quantification, or high-throughput screening (HTS). This
article will review the assays and instruments behind this high-speed
chase. But before jumping into the fast waters of high-throughput (HT)
fluorescence measurements (over 1,000 samples per day), the
predominant techniques will be introduced.
When light hits a fluorophore molecule, it is absorbed and
emitted with less energy to produce fluorescence. The emission
intensity is a measure of fluorophore concentration. Alternatively,
light absorption by a fluorophore can occur close to an appropriate
acceptor that receives it and emits a photon (fluorescence resonance
energy transfer or FRET). Proximity between fluorophores measured by
FRET precisely reflects binding of soluble and membrane-bound
molecules.1
Time-resolved fluorescence (TRF) is a technique that improves
fluorescence quantitation. TRF uses rare-earth lanthanides to provide
a long-lived fluorescent signal. Measuring this type of fluorescence
after a time delay eliminates interference from short-lived background
fluorescence (50 msec or less), improving sensitivity. Wallac(tm)
DELFIA(r) (Dissociation-Enhanced Lanthanide
FluoroImmunoAssay) technology from PerkinElmer Life Sciences
is a form of heterogeneous TRF that relies
on nonfluorescent chelates that can be converted to highly fluorescent
forms using a developing solution.
|
