Self-Degrading, MRI-Detectable Hydrogels with Picomolar Target Sensitivity

Jason Colomb¹, Katherine Louie¹, Stephen P. Massia¹, Kevin M. Bennett¹

Nanostructured hydrogels have been developed as synthetic tissues, tissue scaffolds for cell and drug delivery, and as guides for tissue regeneration. A fundamental problem with hydrogels is that implanted gel structure is difficult to monitor noninvasively. Here we demonstrate that the aggregation of cationic magnetic nanoparticles, attached to specific macromolecules in biological and synthetic hydrogels, can be controlled to detect changes in gel macromolecular structure with MRI. Sensitivity of the gels to target molecules is finely controlled using an embedded zymogen cascade amplifier and we show that these gels self-degrade when they come into contact with pM concentrations of enterokinase.