Abstract
Encapsulating discrete Gd3+ 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 GdDOTP5- into the internal aggregate. In this report we demonstrate that other Gd3+ chelates bearing overall charges as low as 2- can also be used to prepare NACs. This discovery opens up the possibility of using Gd3+ chelates that have inner-sphere water molecules that could further increase the relaxivity enhancement associated with the long τR that arises from encapsulation. However, encapsulation of the q=1 chelate GdDTPA2- did not give rise to a significant increase in relaxivity relative to encapsulation of the outer-sphere chelate GdTTHA3-. 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 Gd3+ chelate encapsulated within NACs arises primarily from second sphere effects.
Original language | English (US) |
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Pages (from-to) | 154-159 |
Number of pages | 6 |
Journal | Contrast Media and Molecular Imaging |
Volume | 11 |
Issue number | 2 |
DOIs | |
State | Published - Mar 1 2016 |
Keywords
- Large payload delivery
- MRI contrast agent
- Nano-encapsulation
ASJC Scopus subject areas
- Radiology Nuclear Medicine and imaging