AUTHOR=Liu Kai , Liu Changcun , Xia Jindong 

TITLE=The r1 relaxivity and T1 imaging properties of dendrimer-based manganese and gadolinium chelators in magnetic resonance imaging

JOURNAL=Frontiers in Bioengineering and Biotechnology

VOLUME=10

YEAR=2022

URL=https://www.frontiersin.org/journals/bioengineering-and-biotechnology/articles/10.3389/fbioe.2022.1004414

DOI=10.3389/fbioe.2022.1004414

ISSN=2296-4185

ABSTRACT=<p>We report the preparation and characterization of gadolinium (Gd)- or manganese (Mn)-loaded dendrimers and Gd-loaded dendrimer-entrapped gold nanoparticles (Gd-Au DENPs) to examine the relationship between the number of metal ion chelators and r<sub>1</sub> relaxivity. In this study, amine-terminated fifth-generation poly(amidoamine) dendrimers (G5.NH<sub>2</sub>) modified with different numbers of DOTA-NHS chelators were used to chelate Gd and Mn ions. The remaining amine groups were then acetylated completely, followed by the use of materials with better r<sub>1</sub> relaxivities and T<sub>1</sub>-weighted imaging performances as templates to synthesize Gd-Au DENPs. The Gd and Mn chelators as well as Gd-Au DENPs were characterized <italic>via</italic> different techniques. We show that the r<sub>1</sub> relaxivity and T<sub>1</sub> imaging performance increase with loading of greater numbers of Gd and Mn ions on the G5.NH<sub>2</sub> and that the acetylation process affects the relaxivity and imaging properties to a certain extent. After entrapment with Au NPs, the r<sub>1</sub> relaxivity and T<sub>1</sub>-weighted imaging performance of Gd-Au DENPs decrease with greater loading of Au NPs. This systematic study of the relaxivities and T<sub>1</sub>-weighted imaging performances of Gd, Mn, and Gd-Au DENP chelators are expected to be a theoretical basis for developing multifunctional dual-mode contrast agents.</p>