Multilamellar hyaluronic acid- <i>b</i> -poly(lactic acid) polymersomes for pathology-responsive MRI enhancement

This study introduces a biocompatible, stimuli-responsive imaging and therapeutic delivery system using ultrasmall iron oxide nanoparticles (USPIONs) encapsulated within the hyaluronic acid-<i>b</i>-poly(lactic acid) (HA-PLA) polymersome membrane, with a model protein bovine serum albumin in the core. These multilamellar vesicles exhibit enhanced <i>T</i>₂-weighted MRI contrast, achieving a relaxivity 3-fold higher than existing agents. The polymersomes demonstrate acid- and enzyme-triggered degradation, enabling controlled release and measurable contrast changes in pathological environments. Preliminary <i>in vivo</i> and postmortem studies confirm their strong imaging performance, high biocompatibility, and targeted response to enzymatic, acidic microenvironments, paving the way for theranostic applications in disease diagnosis and treatment monitoring.