In vivo monitoring of polymers is crucial for drug delivery and tissue regeneration. This study introduces biocompatible and biodegradable polyphosphoesters as MRI-traceable polymers using the ³¹P centers in the polymer backbone. Challenges in ³¹P MRI, including background interference and low sensitivity, are overcome by modifying the molecular environment of ³¹P, assembling polymers into colloids, and tailoring the polymers’ microstructure. Gradient-type polyphosphonate-copolymers show improved MRI-relaxation times. Background-free imaging and biodegradation are validated in vivo using Manduca sexta. Encapsulating the drug PROTAC allows simultaneous drug delivery, enabling theranostics. This work paves the way for polyphosphoesters as background-free MRI-traceable polymers for theranostic applications.

Olga Koshkina, Timo Rheinberger, Vera Flocke, Anton Windfelder, Pascal Bouvain, Naomi M. Hamelmann, Jos M. J. Paulusse, Hubert Gojzewski, Ulrich Flögel, Frederik R. Wurm