Aspects of structural order in 209Bi-containing particles for potential MRI contrast agents based on quadrupole enhanced relaxation

Hermann Scharfetter*, Christian Gösweiner, Paul Josef Krassnig, Carina Sampl, Martin Simon Thonhofer, Roland Fischer, Stefan Spirk, Rupert Kargl, Karin Stana Kleinschek, Evrim Umut, Danuta Kruk

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

Quadrupole relaxation enhancement (QRE) has been suggested as the key mechanism for a novel class of field-selective, potentially responsive magnetic resonance imaging contrast agents. In previous publications, QRE has been confirmed for solid compounds containing 209Bi as the quadrupolar nucleus (QN). For QRE to be effective in aqueous dispersions, several conditions must be met, i.e. high transition probability of the QN at the 1H Larmor frequency, water exchange with the bulk and comparatively slow motion of the Bi-carrying particles. In this paper, the potential influence of structural order within the compounds (‘crystallinity’) on QRE was studied by nuclear quadrupole resonance (NQR) spectroscopy in one crystalline and two amorphous preparations of Triphenylbismuth (BiPh3). The amorphous preparations comprised (1) a shock-frozen melt and (2) a granulate of polystyrene which contained homogeneously distributed BiPh3 after common dissolution in THF and subsequent evaporation of the solvent. In contrast to the crystalline powder which exhibits strong, narrow NQR peaks the amorphous preparations did not reveal any NQR signals above the noise floor. From these findings, we conclude that the amorphous state leads to a significant spectral peak broadening and that for efficient QRE in potential contrast agents structures with a high degree of order (near crystalline) are required.

Original languageEnglish
Pages (from-to)935-943
Number of pages10
JournalMolecular Physics
Volume117
Issue number7-8
Early online date22 Aug 2018
DOIs
Publication statusPublished - 2019

Fields of Expertise

  • Human- & Biotechnology

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