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2016-03-08 - Colloque/Présentation - poster - Anglais - 1 page(s)

Callewaert M., Rigaux G, Belabassi Yamina, cadiou C, Moreau Juliette, Molinari M., Portefaix C., Henoumont Céline , Vander Elst Luce , Muller Robert , Bauduin B, Boutry Sébastien , Dinischiotu Anca, Chuburu F., Laurent Sophie , "New biocompatible nanohydrogels to obtain highly efficient MRI Gd contrast agents" in 11th annual meeting of the European Society for Molecular Imaging (ESMI), Utrecht, the Netherlands , 2016

  • Codes CREF : Physico-chimie générale (DI1320), Chimie des colloïdes (DI1329)
  • 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)
  • Centres UMONS : Centre de Recherche en Microscopie et Imagerie Médicale (CMMI)

Abstract(s) :

(Anglais) Magnetic resonance imaging (MRI) is one of the most powerful non-invasive techniques for clinical diagnosis. However, the use of paramagnetic contrast agents (CA) is often required to distinguish healthy and diseased tissues. The most commonly used contrast agents are gadolinium chelates (GdCA). Nevertheless they suffer from some limitations because their relaxivities are far from the ones predicted by the theory. To circumvent these limitations, a series of GdCA-loaded polysaccharide-based nanohydrogels (GdCANPs) have been prepared.1 These biocompatible nanohydrogels, elaborated by a gelation process2 involving chitosan and hyaluronan, encapsulate various GdCA in a highly hydrated nanostructure. According to the nature of the polymer matrix and to the cross-linking ability of the GdCA, r1 relaxivities per Gd centre as high as 100 s-1 mM-1 at 30 MHz can be reached. The NMRD profiles confirm that molecular motions of the Gd chelates are effectively restricted and that water access to the inner core of these nanogels is not limited. On T1- and T2-weighted images recorded at 3 T, this relaxation enhancement is clearly translated into a magnified contrast, demonstrating the powerful dual mode imaging ability of such nanosytems. A multiparametric approach combining three different tests, MTT (to evaluate the mitochondrial activity), SRB (to evaluate the evolution of the total cell biomass), LDH (to evaluate the damages done in the membranes) was then adopted to evaluate the cytotoxicity of the GdCANPs. The first results indicated that no major cytotoxicity was observed even at 24 h for the higher concentration in Gd (5 µM) and a good cellular proliferation was maintained in the presence of nanohydrogels. Finally, GdCANPs were used as contrastophores for lymphatic system imaging (T1-weighted images, 9.4T). Twenty minutes after subcutaneous injection in the left hock of a C57Bl6-derived mouse, GdCANPs uptake happened and lymphatic vessels can be highlighted. REFERENCES: 1. T. Courant et al. Hydrogels Incorporating GdDOTA: Towards Highly Efficient Dual T1/T2 MRI Contrast Agents, Angew. Chem. Int. Ed. 2012, 51, 911 2. F. A. Oyarzun-Ampuero et al. Chitosan-hyaluronic acid nanoparticles loaded with heparin for the treatment of asthma. Int. J. Pharm. 2009, 381, 122