NDLI: Gold nanoparticles functionalised with fast water exchanging $Gd^{3+}$ chelates: linker effects on the relaxivity

Content Provider	World Health Organization (WHO)-Global Index Medicus
Author	Rodrigues, Sérgio P. J. Cerdan, Sebastian Martins, José A. Prata, Maria I. M. Mousavi, Bibimaryam Gonçalves, Janaina Ferreira, Paula M. Rodrigues, Tiago B. López-larrubia, Pilar Ferreira, Miguel F. Helm, Lothar Calle, Daniel Geraldes, Carlos F. G. C.
Description	Author Affiliation: Ferreira MF ( Centro de Química, Campus de Gualtar, Universidade do Minho, 4710-057 Braga, Portugal. jmartins@quimica.uminho.pt.)
Abstract	The relaxivity displayed by $Gd^{3+}$ chelates immobilized onto gold nanoparticles is the result of the complex interplay between the nanoparticle size, the water exchange rate and the chelate structure. In this work we study the effect of the length of ω-thioalkyl linkers, anchoring fast water exchanging $Gd^{3+}$ chelates onto gold nanoparticles, on the relaxivity of the immobilized chelates. Gold nanoparticles functionalized with $Gd^{3+}$ chelates of mercaptoundecanoyl and lipoyl amide conjugates of the DO3A-N-(α-amino)propionate chelator were prepared and studied as potential CA for MRI. High relaxivities per chelate, of the order of magnitude 28–38 $mM^{−1}$ $s^{−1}$ (30 MHz, 25 °C), were attained thanks to simultaneous optimization of the rotational correlation time and of the water exchange rate. Fast local rotational motions of the immobilized chelates around connecting linkers (internal flexibility) still limit the attainable relaxivity. The degree of internal flexibility of the immobilized chelates seems not to be correlated with the length of the connecting linkers. Biodistribution and MRI studies in mice suggest that the in vivo behavior of the gold nanoparticles was determined mainly by size. Small nanoparticles (HD = 3.9 nm) undergo fast renal clearance and avoidance of the RES organs while larger nanoparticles (HD = 4.8 nm) undergo predominantly hepatobiliary excretion. High relaxivities, allied to chelate and nanoparticle stability and fast renal clearance in vivo suggest that functionalized gold nanoparticles hold great potential for further investigation as MRI contrast agents. This study contributes to a better understanding of the effect of linker length on the relaxivity of gold nanoparticles functionalized with $Gd^{3+}$ complexes. It is a relevant contribution towards “design rules” for nanostructures functionalized with $Gd^{3+}$ chelates as Contrast Agents for MRI and multimodal imaging.
ISSN	14779226
Issue Number	9
Volume Number	44
e-ISSN	13645447
Journal	Dalton Trans.
Language	English
Publisher	Royal Society of Chemistry
Publisher Date	2015-03-07
Publisher Place	Great Britain (UK)
Access Restriction	Subscribed
Subject Keyword	Chelating Agents Chemistry Contrast Media Coordination Complexes Gadolinium Gold Metal Nanoparticles Animals Pharmacokinetics Male Mice Rats, Wistar Tissue Distribution Water Journal Article Research Support, Non-U.S. Gov't
Content Type	Text
Resource Type	Article
Subject	Inorganic Chemistry

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