Analysis of Lanthanide
Complex Dendrimer Conjugates
for Bimodal NIR and MRI Imaging
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Abstract
Advances in clinical diagnostic instrumentation have
enabled some
imaging modalities to be run concurrently. For diagnostic purposes,
multimodal imaging can allow for rapid location and accurate identification
of a patient’s illness. The paramagnetic and near-infrared
(NIR) properties of Dy(III) and Yb(III) are interesting candidates
for the development of bimodal NIR and magnetic resonance imaging
(MRI) contrast agents. To enhance their intrinsic bimodal properties,
these lanthanides were chelated using the hexadentate-all-oxygen-donor-ligand
TREN-bis(1-Me)-3,2-HOPO-TAM-NX (NX, where X = 1, 2, or 3) and subsequently
conjugated to the esteramide dendrimer (EA) to improve bioavailability,
solubility, and relaxivity. Of these new complexes synthesized and
evaluated, DyN1-EA had the largest ionic <i>T</i><sub>1</sub> relaxivity, 7.60 mM<sup>–1</sup> s<sup>–1</sup>, while
YbN3-EA had the largest ionic <i>T</i><sub>2</sub> relaxivity
with a NIR quantum yield of 0.17% when evaluated in mouse serum. This
is the first Yb(III) bimodal NIR/<i>T</i><sub>2</sub> MRI
contrast agent of its kind evaluated
