Phosphorothioate groups containing polymer as a pioneering metal-free contrast agent for ³¹P-MRI

Herein, we describe the synthesis and MR characterization of a pioneering metal-free ³¹P-MR contrast agent based on phosphorus bearing polymer. Poly[O-(2-(methacryloyloxy) ethyl) O-(2-(trimethylamoniumyl)- ethyl) phosphorothioate] (pTMPC) is a well defined hydrophilic nanomaterial characterized by a high content of naturally rare phosphorothioate groups providing a high-intensity ³¹P-MR signal distant from the phosphorus biomolecules, making it easily distinguishable from biological background both in vitro and in vitro. Furthermore, pTMPC is prone to oxidation in the presence of reactive oxygen species, which is also detectable by ³¹P-MR. Add to this the favorable ¹H and ³¹P T1/T2 relaxation times and biocompatibility, pTMPC represents a conceptually new contrast agent, whose discovery opens up new possibilities in the field of ³¹P-MR imaging. (authors)