| Autor: |
Asik D; Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA., Smolinski R; Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA., Abozeid SM; Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA., Mitchell TB; Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA., Turowski SG; Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, NY 14263, USA., Spernyak JA; Department of Cell Stress Biology, Roswell Park Comprehensive Cancer Center, NY 14263, USA., Morrow JR; Department of Chemistry, University at Buffalo, The State University of New York, Amherst, NY 14260, USA. |
| Abstrakt: |
Complexes of Fe(III) that contain a triazacyclononane (TACN) macrocycle, two pendant hydroxyl groups, and a third ancillary pendant show promise as MRI contrast agents. The ancillary group plays an important role in tuning the solution relaxivity of the Fe(III) complex and leads to large changes in MRI contrast enhancement in mice. Two new Fe(III) complexes, one with a third coordinating hydroxypropyl pendant, Fe(L2), and one with an anionic non-coordinating sulfonate group, Fe(L1)(OH 2 ), are compared. Both complexes have a deprotonated hydroxyl group at neutral pH and electrode potentials representative of a stabilized trivalent iron center. The r 1 relaxivity of the Fe(L1)(OH 2 ) complex is double that of the saturated complex, Fe(L2), at 4.7 T, 37 °C in buffered solutions. However, variable-temperature 17 O-NMR experiments show that the inner-sphere water of Fe(L1)(OH 2 ) does not exchange rapidly with bulk water under these conditions. The pendant sulfonate group in Fe(L1)(OH 2 ) confers high solubility to the complex in comparison to Fe(L2) or previously studied analogues with benzyl groups. Dynamic MRI studies of the two complexes showed major differences in their pharmacokinetics clearance rates compared to an analogue containing a benzyl ancillary group. Rapid blood clearance and poor binding to serum albumin identify Fe(L1)(OH 2 ) for development as an extracellular fluid contrast agent. |
