5th EuropEan MolEcular IMagIng MEEtIng - ESMI

5th EuropEan MolEcular IMagIng MEEtIng – EMIM2010
Lanthanide-based in vivo luminescence imaging
Petoud S. .
CNRS, France
spetoud@pitt.edu
Introduction: Fluorescence and luminescence
are detection techniques that possess important
advantages for bioanalytical applications and
biologic imaging: high sensitivity, versatility and
low costs of instrumentation. A common characteristic
of biologic analytes is their presence in
small quantities among complex matrices such as
blood, cells, tissue and organs. These matrices
emit significant background fluorescence (autofluorescence),
limiting detection sensitivity.
The luminescence of lanthanide cations has several
complementary advantages over the fluorescence
of organic fluorophores and semiconductor
nanocrystals, such as sharp emission bands for
spectral discrimination from background emission,
long luminescence lifetimes for temporal
discrimination and strong resistance to photobleaching.
In addition, several lanthanides emit
near-infrared (NIR) photons that can cross deeply
into tissues for non-invasive investigations and
that result in improved detection sensitivity due
to the absence of native NIR luminescence from
tissues and cells. The main requirement to obtain
lanthanide emission is to sensitize them with an
appropriate chromophore.
Methods: An innovative concept for such sensitization
of lanthanide cations is proposed herein;
the current limitation of low quantum yields
experienced by most mononuclear lanthanide
complexes is compensated for by using larger
numbers of lanthanide cations and by maximizing
the absorption of each discrete molecule,
thereby increasing the number of emitted photons
per unit of volume and the overall sensitivity
of the measurement. To apply this concept, we
are developing a family of dendrimer-naphthalimide
ligands that are able to incorporate several
lanthanide cations. Polyamidoamine (PAMAM)
dendrimers have been chosen as a basis for these
complexes because the oxygen atoms of the amido
groups located along their branches can bind
and protect the lanthanide cations inside the
dendrimer core.1,2 Derivatives of naphthalimide
groups, required for the sensitization of the lanthanide
cations, are located at the branch termini.
Our synthetic approach allows facile modification
of the dendrimer complex for control over
photophysical properties and solubility. It also
provides for the attachment of different types
of targeting agents such as peptides, oligonucleotides
or proteins, as well as other sensing agents,
to provide functionality to these compounds in a
broad range of applications.
Results: In this paper, we will describe several
examples of luminescent polymetallic lanthanide
complexes based on dendrimers. We will also
present examples of their applications as reporters
and sensors for biologic imaging in living cells
and small animals.
References:
1. J. P. Cross, M. Lauz, P. D. Badger, S. Petoud, Journal of
the American Chemical Society, 2004, 126, 16278.
2. D. R. Kauffman, C. M. Shade, H. Uh, A. Star and S. Petoud,
Nature Chemistry 2009, 1, 500.
EuropEan SocIEty for MolEcular IMagIng – ESMI
day1
Parallel Session 4: PROBES - supported by COST