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2008-01-01 - Colloque/Présentation - poster - Anglais - 1 page(s)

Henoumont Céline , Henrotte Virginie, Laurent Sophie , Vander Elst Luce , Muller Robert , "Study of non covalent interactions between some MRI contrast agents and human serum albumin by NMR diffusometry" in Euromar, Magnetic Resonance for the Future, St-Petersbourg, Russie, 2008

  • Codes CREF : Résonance magnétique nucléaire (biophysique) (DI131B)
  • Unités de recherche UMONS : Chimie générale, organique et biomédicale (M108)
  • Instituts UMONS : Institut des Sciences et Technologies de la Santé (Santé), Institut des Biosciences (Biosciences)

Abstract(s) :

(Anglais) Magnetic resonance imaging (MRI) has a spatial and temporal resolution better than that of other imaging techniques, making it a powerful tool for the diagnosis of several diseases. Its sensitivity is however quite low and has to be compensated by the use of contrast agents. Most of them are gadolinium complexes which have the property of increasing the signal of the pathological zones, improving the image contrast. The challenge of the chemists is thus to increase the efficacy of these contrast agents in order to reduce the quantity to inject and to improve the image quality. One way is to design molecules with a high affinity for endogenous macromolecules. In this context, techniques allowing the estimation of non covalent interactions are of paramount importance. The NMR diffusometry technique1 is used in this work to evaluate the affinity of four MRI contrast agents for human serum albumin (HSA), used as a model of macromolecular target. The principle of this method is based on the variation of the ligand diffusion coefficient in the absence and in the presence of HSA. However, this high resolution NMR technique does not allow to use gadolinium complexes because of the signal broadening they produce. Lanthanium and europium ions were therefore used to replace gadolinium ion. The results show the importance of one parameter in the sequence used, which is the diffusion time called big delta (?). It is indeed during this period that the exchange between the free and the bound forms of the contrast agent can take place. So, if the residence time is longer than ?, no evidence of the interaction between the contrast agent and HSA will appear. On the contrary, if ? is longer than the residence time, a difference between the diffusion coefficient of the contrast agent alone in solution and in the presence of HSA becomes evident. In such conditions, the technique becomes very interesting because it can provide an estimation of the thermodynamic and of the kinetic parameters of the interactions. 1. Lucas, L.H., Larive, C.K., Conc. Magn. Res. 2004, Part A, 20A(1), 24-41