Phosphorus-Containing Polymeric Zwitterion: A Pioneering Bioresponsive Probe for ³¹ P-Magnetic Resonance Imaging

³¹ P-magnetic resonance (MR) is an important diagnostic technique currently used for tissue metabolites assessing, but it also has great potential for visualizing the internal body structures. However, due to the low physiological level of phosphorus-containing biomolecules, precise imaging requires the administration of an exogenous probe. Herein, this work describes the synthesis and MR characterization of a pioneering metal-free ³¹ P-MR probe based on phosphorus-containing polymeric zwitterion. The developed probe (pTMPC) is a well-defined water-soluble macromolecule characterized by a high content of naturally rare phosphorothioate groups providing a high-intensity ³¹ P-MR signal clearly distinguishable from biological background both in vitro and in vitro. In addition, pTMPC can serve as a sensitive ³¹ P-MR sensor of pathological conditions in vivo because it undergoes oxidation-induced structural changes in the presence of reactive oxygen species (ROS). Add to this the favorable ¹ H and ³¹ P T₁ /T₂ relaxation times and biocompatibility, pTMPC represents a conceptually new diagnostic, whose discovery opens up new possibilities in the field of ³¹ P-MR spectroscopy and imaging.