Open AccessNano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd 3+ ‐based MRI contrast agents
Author(s) -
Farashishiko Annah,
Chacón Kelly N.,
Blackburn Ninian J.,
Woods Mark
Publication year - 2015
Publication title -
contrast media & molecular imaging
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.714
H-Index - 50
eISSN - 1555-4317
pISSN - 1555-4309
DOI - 10.1002/cmmi.1676
Subject(s) - chelation , encapsulation (networking) , gadolinium , chemistry , mri contrast agent , molecule , nanotechnology , crystallography , combinatorial chemistry , materials science , organic chemistry , computer network , computer science
Encapsulating discrete Gd 3+ chelates in nano‐assembled capsules (NACs) is a simple and effective method of preparing an MRI contrast agent capable of delivering a large payload of high relaxivity imaging agent. The preparation of contrast agent containing NACs had previously focussed on preparations incorporating GdDOTP 5‐ into the internal aggregate. In this report we demonstrate that other Gd 3+ chelates bearing overall charges as low as 2‐ can also be used to prepare NACs. This discovery opens up the possibility of using Gd 3+ chelates that have inner‐sphere water molecules that could further increase the relaxivity enhancement associated with the long τ R that arises from encapsulation. However, encapsulation of the q = 1 chelate GdDTPA 2‐ did not give rise to a significant increase in relaxivity relative to encapsulation of the outer‐sphere chelate GdTTHA 3‐ . This leads us to the conclusion that in the NAC interior proton transport is not mediated by movement of whole water molecules and the enhanced relaxivity of Gd 3+ chelate encapsulated within NACs arises primarily from second sphere effects. Copyright © 2015 John Wiley & Sons, Ltd.