发信人: WhiteMerlot (Merlot), 信区: Chemistry
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发信站: BBS 未名空间站 (Sun Aug  9 14:04:56 2009, 美东)

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Nature Materials
Published online: 9 August 2009 | doi:10.1038/nmat2509

http://www.nature.com/nmat/journal/vaop/ncurrent/abs/nmat2509.h

A dual-emissive-materials design concept enables tumour hypoxia imaging
Guoqing Zhang1, Gregory M. Palmer2, Mark W. Dewhirst2 & Cassandra L.
Fraser1

Luminescent materials are widely used for imaging and sensing owing to
their high sensitivity, rapid response and facile detection by many
optical technologies1. Typically materials must be chemically tailored
to achieve intense, photostable fluorescence, oxygen-sensitive
phosphorescence or dual emission for ratiometric sensing, often by
blending two dyes in a matrix. Dual-emissive materials combining all of
these features in one easily tunable molecular platform are desirable,
but when fluorescence and phosphorescence originate from the same dye,
it can be challenging to vary relative fluorescence/phosphorescence
intensities for practical sensing applications. Heavy-atom substitution2
alone increases phosphorescence by a given, not variable amount. Here,
we report a strategy for modulating fluorescence/phosphorescence for a
single-component, dual-emissive, iodide-substituted difluoroboron
dibenzoylmethane-poly(lactic acid) (BF2dbm(I)PLA) solid-state sensor
material. This is accomplished through systematic variation of the PLA
chain length in controlled solvent-free lactide polymerization3 combined
with heavy-atom substitution2. We demonstrate the versatility of this
approach by showing that films made from low-molecular-weight
BF2dbm(I)PLA with weak fluorescence and strong phosphorescence are
promising as 'turn on' sensors for aerodynamics applications4, and that
nanoparticles fabricated from a higher-molecular-weight polymer with
balanced fluorescence and phosphorescence intensities serve as
ratiometric tumour hypoxia imaging agents.

Department of Chemistry, University of Virginia, Charlottesville,
Virginia 22904, USA
Department of Radiation Oncology, Duke University Medical Center,
Durham, North Carolina 27710, USA
Correspondence to: Cassandra L. Fraser1 e-mail: fraser@virginia.edu

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