Design and Synthesis
of Fluorinated Amphiphile as <sup>19</sup>F MRI/Fluorescence Dual-Imaging
Agent by Tuning the Self-Assembly
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Abstract
Both <sup>19</sup>F MRI and optical imaging are powerful noninvasive
molecular imaging modalities in biomedical applications. To integrate
these two complementary imaging modalities, the design and synthesis
of a novel <sup>19</sup>F MRI/fluorescence dual-modal imaging agent
is reported herein. Through Sonogashira coupling reaction between
the fluorinated phenylacetylene and 1,2,4,5-tetraiodobenzene, a fluorophore
with 48 symmetrical fluorines at its periphery was constructed with
high efficacy. High aqueous solubility was achieved by PEGylation
of the fluorophore with monodisperse PEGs. However, an unexpected
self-assembly of the PEGylated amphiphilic fluorophore in water “turned
off” the <sup>19</sup>F NMR signal. However, hydrogenation
of the triple bonds or introduction of branched monodisperse PEGs
was able to efficiently tune the self-assembly, resulting in the “turning
on” of the <sup>19</sup>F NMR signal. One of these amphiphiles
combines the advantages of label-free fluorescence, high <sup>19</sup>F MRI sensitivity, biocompatibility, and excellent aqueous solubility.
The results demonstrate the great potential of such amphiphiles for
real-time <sup>19</sup>F MRI and fluorescence dual-modality imaging