High‐Relaxivity MRI Contrast Agents: Where Coordination Chemistry Meets Medical Imaging

3,4,3-LI(1,2-HOPO): In vitro formation of highly stable lanthanide complexes translates into efficacious in vivo europium decorporation

“…Emission spectra were acquired on a HORIBA Jobin Yvon IBH FluoroLog-3 spectrofluorimeter, equipped with 3 slit double grating excitation and emission monochromators (2.1 nm/mm dispersion, 1200 grooves/mm). Spectra were reference corrected for both the excitation light source variation (lamp and grating) and the emission spectral 5 response (detector and grating). Luminescence lifetimes were determined on a HORIBA Jobin Yvon IBH FluoroLog-3 spectrofluorimeter, adapted for time-correlated single photon counting (TCSPC) and multichannel scaling (MCS) measurements.…”

“…Other techniques such as NMR or X-ray absorption spectroscopies may be used in the future to characterize and compare the coordination spheres of these metal complexes. The in vivo distribution patterns and biokinetics of the lanthanides have been investigated previously, 29,30 revealing an increase in bone 5 retention and a decrease in liver deposition along the lanthanide series. These patterns may be linked to an increase in lanthanide complex stability with the phosphate binding moieties of the bone matrices, similar to the stability increases observed with 3,4,3-LI(1,2-HOPO), as the metal ion becomes smaller and more acidic.…”

“…[1][2][3][4][5] The octadentate ligand 3,4,3-LI(1,2-HOPO) ( Fig. 1), composed of four 1-hydroxy-pyridin-2-one (1,2-HOPO) units linked to a spermine scaffold through amide linkages, is currently considered the most efficient experimental decorporation agent for actinides.…”

“…The emission spectrum of each solution was measured using a 1-cm quartz cell (λ exc = 325 nm, λ em = 570-720 nm). The data was then 5 imported into the refinement program HypSpec [10][11][12][13][14][15] and analyzed by nonlinear least-squares refinement.…”

Two Binuclear Nonionic Magnetic Resonance Contrast Agents with High Relaxivity

“…[5] However, because of the disadvantages such as rapid clearance, poor cell uptake, non-specific binding and especially low relaxivity of these GBCAs, the development of higher relaxivity CAs is necessary. [6] According to Solomon-Bloembergen-Morgan (SBM) equation, the relaxivity of GBCAs is mainly determined by residence time (τ M ), the number of first-shell (inner) water molecules (q), rotational correlation time (τ R ), and electron spin relaxation time (T 1e ). For small molecular weight GBCAs, either increasing the parameter q or lengthening τ R could enhance the relaxivity.…”