000088428 001__ 88428
000088428 005__ 20180317094241.0
000088428 0247_ $$2doi$$a10.1021/ja044688h
000088428 02470 $$2ISI$$a000226324500064
000088428 037__ $$aARTICLE
000088428 245__ $$aWater-Soluble Gadofullerenes: Toward High-Relaxivity, pH-Responsive MRI Contrast Agents
000088428 269__ $$a2005
000088428 260__ $$c2005
000088428 336__ $$aJournal Articles
000088428 520__ $$aThe water-soluble endohedral gadofullerene derivatives, Gd@C60(OH)x and Gd@C60[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 × 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@C60[C(COOH)2]10 and 38.5 mM-1 s-1 for Gd@C60(OH)x at 299 K. Variable-temperature, transverse and longitudinal 17O 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 R298 = 2.6 ns. The proton exchange rate obtained for Gd@C60[C(COOH)2]10 is kex298 = 1.4 × 107 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@C60(OH)x and Gd@C60[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.
000088428 6531_ $$afullerenes
000088428 6531_ $$amagnetic resonance imaging
000088428 6531_ $$acontrast agents
000088428 700__ $$aTóth, Éva
000088428 700__ $$aBolskar, Robert D.
000088428 700__ $$0240739$$aBorel, Alain$$g148230
000088428 700__ $$aGonzález, Gabriel
000088428 700__ $$0240250$$aHelm, Lothar$$g144957
000088428 700__ $$0241569$$aMerbach, André E.$$g123257
000088428 700__ $$aSitharaman, Balaji
000088428 700__ $$aWilson, Lon J.
000088428 773__ $$j127$$k2$$q799 -805$$tJournal of the American Chemical Society
000088428 909CO $$ooai:infoscience.tind.io:88428$$particle$$pSB
000088428 909C0 $$0252059$$pLCIB$$xU10103
000088428 937__ $$aLCIB-ARTICLE-2006-004
000088428 973__ $$aEPFL$$rREVIEWED$$sPUBLISHED
000088428 980__ $$aARTICLE