title: Characterisation and application of ultra-high spin clusters as magnetic resonance relaxation agents.
abstract: In Magnetic Resonance Tomography (MRT) image contrast can be improved by adding paramagnetic relaxation agents such as lanthanide ions. Here we report on the use of highly paramagnetic isostructural Fe(III)/4f coordination clusters with a [Fe10Ln10] core to enhance relaxation. Measurements were performed over the range of (1)H Larmor frequencies of 10 MHz to 1.4 GHz in order to determine the relevant parameters for longitudinal and transverse relaxivities. Variation of the lanthanide ion allows differentiation of relaxation contributions from electronic states and molecular dynamics. We find that the transverse relaxivities increase with field, whereas the longitudinal relaxivities depend on the nature of the lanthanide. In addition, the Gd(III) analogue was selected in particular to test the interaction with tissue observed using MRT. Studies on biofilms used in waste water treatment reveal that the behaviour of the high-spin clusters is different from what is observed for common relaxation agents with respect to the penetration into the biofilms. The Fe10Gd10 cluster adheres to the surface of the biofilm better than the commercial agent Gadovist.
authors: Pro2NMR at the Institutes for Biological Interfaces and for Mechanical Processes Engineering and Mechanics, KIT, Adenauerring 20b, D-76131 Karlsruhe, Germany. gisela.guthausen@kit.edu.
authors: Gisela
authors: G
authors: Guthausen
authors: Julyana R
authors: JR
authors: Machado
authors: Burkhard
authors: B
authors: Luy
authors: Amer
authors: A
authors: Baniodeh
authors: Annie K
authors: AK
authors: Powell
authors: Steffen
authors: S
authors: Krämer
authors: Florian
authors: F
authors: Ranzinger
authors: Maria P
authors: MP
authors: Herrling
authors: Susanne
authors: S
authors: Lackner
authors: Harald
authors: H
authors: Horn