Investigations into the effects of linker length elongation on the behaviour of calcium-responsive MRI probes

Abstract

The effects of subtle structural changes on the coordination behaviour and subsequent relaxometric properties of two novel calcium-responsive magnetic resonance imaging probes have been assessed via a range of physicochemical techniques.

Recent progress on MRI probes for metal ion detection and biological applications

“…Recently, other Ca 2+ -responsive MRI probes (Fig. 4C, named GdL1 and GdL2) with different linker lengths between the MRI signaling unit and Ca 2+ -responsive moieties were developed by Angelovski et al 51 The total r 1 and r 2 relaxivity changes for GdL 2 were measured by relaxometric titrations of both probes and were determined to be 131 and 138%, respectively. Greater r 1 and r 2 relaxivity modifications in GdL2 showed that even small structural variations between the acyclic Ca 2+ binding unit and the macrocyclic Gd( iii ) ligand might result in significantly different relaxation characteristics of the Gd( iii ) complex.…”

“…Recently, two monomeric bifunctional chelators that can act as Ca 2+ -responsive contrast agents were described by Angelovski et al 55 According to the results of the relaxometric nuclear magnetic resonance titrations, there were no detectable changes in the r 1 signals of the probe in the presence of Ca 2+ . Due to the interaction of GdL2 with extracellular Ca 2+ , the T 1 -weighted signal intensity of MRI rapidly dropped, reaching up to 5% of the difference in the detrended signal.…”