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Article Dans Une Revue Journal of the American Chemical Society Année : 2005

Water-Soluble Gadofullerenes: Toward High-Relaxivity, pH-Responsive MRI Contrast Agents

Éva Tóth
Robert Bolskar
  • Fonction : Auteur
Alain Borel
  • Fonction : Auteur
André Merbach
  • Fonction : Auteur
Balaji Sitharaman
  • Fonction : Auteur
Lon Wilson
  • Fonction : Auteur

Résumé

The water-soluble endohedral gadofullerene derivatives, Gd@C(60)(OH)(x) and Gd@C(60)[C(COOH)(2)](10), have been characterized with regard to their MRI contrast agent properties. Water-proton relaxivities have been measured in aqueous solution at variable temperature (278-335 K), and for the first time for gadofullerenes, relaxivities as a function of magnetic field (5 x 10(-4) to 9.4 T; NMRD profiles) are also reported. Both compounds show relaxivity maxima at high magnetic fields (30-60 MHz) with a maximum relaxivity of 10.4 mM(-1) s(-1) for Gd@C(60)[C(COOH)(2)](10) and 38.5 mM(-1) s(-1) for Gd@C(60)(OH)(x) at 299 K. Variable-temperature, transverse and longitudinal (17)O relaxation rates, and chemical shifts have been measured at three magnetic fields (B = 1.41, 4.7, and 9.4 T), and the results point exclusively to an outer sphere relaxation mechanism. The NMRD profiles have been analyzed in terms of slow rotational motion with a long rotational correlation time calculated to be tau(R)(298) = 2.6 ns. The proton exchange rate obtained for Gd@C(60)[C(COOH)(2)](10) is k(ex)(298) = 1.4 x 10(7) s(-1) which is consistent with the exchange rate previously determined for malonic acid. The proton relaxivities for both gadofullerene derivatives increase strongly with decreasing pH (pH: 3-12). This behavior results from a pH-dependent aggregation of Gd@C(60)(OH)(x) and Gd@C(60)[C(COOH)(2)](10), which has been characterized by dynamic light scattering measurements. The pH dependency of the proton relaxivities makes these gadofullerene derivatives prime candidates for pH-responsive MRI contrast agent applications.

Dates et versions

hal-02080406 , version 1 (26-03-2019)

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Citer

Éva Tóth, Robert Bolskar, Alain Borel, Gabriel Gonzalez, Lothar Helm, et al.. Water-Soluble Gadofullerenes: Toward High-Relaxivity, pH-Responsive MRI Contrast Agents. Journal of the American Chemical Society, 2005, 127 (2), pp.799-805. ⟨10.1021/ja044688h⟩. ⟨hal-02080406⟩
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