Nano assembly and encapsulation; a versatile platform for slowing the rotation of polyanionic Gd3+-based MRI contrast agents

Annah Farashishiko, Kelly N. Chacón, Ninian Blackburn, Mark Woods

Research output: Contribution to journalArticle

2 Scopus citations


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 languageEnglish (US)
JournalContrast Media and Molecular Imaging
StateAccepted/In press - 2016


  • Large payload delivery
  • MRI contrast agent
  • Nano-encapsulation

ASJC Scopus subject areas

  • Radiology Nuclear Medicine and imaging

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