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Bimodal nanoprobes based on non-covalent association of Gd(III) chelates and anionic or cationic quantum dots for optical and magnetic resonance imaging
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1  Federal University of Pernambuco

Abstract:

Magnetic resonance imaging (MRI) is one of the most applied imaging techniques in the clinical diagnostic field. The main advantages of the MRI are its high spatial resolution compared with other clinical techniques and its ability to distinguish soft tissues altered by some abnormality. However, the low sensitivity and insufficient contrast are significant drawbacks of this technique. To improve the image resolution, frequently are applied contrast agents (CAs), such as Gd(III) chelates. Several approaches have been reported to increase the efficiency of these CAs, and among them are nanoparticulate systems. Moreover, by associating MRI CAs with fluorescent nanoparticles, it is possible to obtain versatile dual nanoprobes. Quantum dots (QDs) are fluorescent nanocrystals, which have been widely used in biomedical sciences due to their high photostability and chemically active surface. In this work, we developed bimodal nanosystems by associating CdTe QDs with Gd(III) chelates (DOTA and DTPA). Intending to compare the effect of the stabilizing functional groups in the CAs relaxivity, we used carboxylated and amine-coated QDs. The Gd(III) chelates, modified with a thiol group, were attached to the QDs surface, affording the bimodal systems. Our preliminary results showed that the stabilizing agent influences the relaxivity values of these bimodal nanoprobes. Nevertheless, the optical and relaxometric characterizations showed that these nanoprobes have potential to be used as CAs for optical and MR imaging.

Keywords: bimodal system, contrast agent, Gd (III) chelates, magnetic resonance imaging, quantum dots
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