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High Relaxivity with No Coordinated Waters: A Seemingly Paradoxical Behavior of [Gd(DOTP)] 5- Embedded in Nanogels.

Fabio CarniatoMarco RicciLorenzo TeiFrancesca GarelloEnzo TerrenoEnrico RaveraGiacomo ParigiClaudio LuchinatMauro Botta
Published in: Inorganic chemistry (2022)
Nanogels (NGs) obtained by electrostatic interactions between chitosan and hyaluronic acid and comprising paramagnetic Gd chelates are gaining increasing attention for their potential application in magnetic resonance bioimaging. Herein, the macrocyclic complexes [Gd(DOTP)] 5- , lacking metal-bound water molecules ( q = 0), were confined or used as a cross-linker in this type of NG. Unlike the typical behavior of Gd complexes with q = 0, a remarkable relaxivity value of 78.0 mM -1 s -1 was measured at 20 MHz and 298 K, nearly 20 times greater than that found for the free complex. A careful analysis of the relaxation data emphasizes the fundamental role of second sphere water molecules with strong and long-lived hydrogen bonding interactions with the complex. Finally, PEGylated derivatives of nanoparticles were used for the first in vivo magnetic resonance imaging study of this type of NG, revealing a fast renal excretion of paramagnetic complexes after their release from the NGs.
Keyphrases
  • hyaluronic acid
  • magnetic resonance
  • magnetic resonance imaging
  • drug delivery
  • contrast enhanced
  • computed tomography
  • electronic health record
  • working memory
  • machine learning
  • single molecule
  • human health