POLYMER COATED LANTHANIDE PHOSPHATE NANOPARTICLES AS MRI CONTRAST AGENTS

Pratik Roy, Daniel R. Talham

Department of Chemistry, University of Florida, Gainesville, FL 32611-7200, USA

Lanthanide based Paramagnetic Chemical Exchange Saturation Transfer (PARACEST) agents offer an alternative to T1 and T2 based contrast agents. These systems rely on dynamic chemical exchange of labile protons with bulk water and lead to a decrease in magnetization giving negative contrast in MRI. The major advantage is that one can turn ‘on’ and ‘off’ the image contrast by the application of external radiofrequency pulse. All published examples of PARACEST agents are single molecule systems. Here we present a novel approach to prepare polymer coated lanthanide phosphate nanoparticles, which can act as potential PARACEST agents. A synthesis scheme utilizing reverse micelles of the polymer in oil and water, which is essential in controlling the particle size has been developed. Using ¹H NMR we have observed the shifted proton peaks due to the presence of paramagnetic Ln³⁺ ions.