polymer-coated cerium oxide based device and system is disclosed for detecting reactive oxygen species and monitoring chronic inflammation. The device and system encapsulate free therapeutic nanoparticle elements not present in a living body in a prosthetic or implantable unit. In one embodiment, the unit is a structure with a reactive oxygen species (ROS) scavenging component on one end and at the opposite end is an imaging agent consisting of at least one of the fluorophore capable of fluorescence emission, a chemiluminescent agent, a magnetic relaxation agent and an X-ray contrast agent. In a second embodiment, a single chamber device consisting of a multifunctional nanocomposite has a ROS-scavenging nanoparticle constituent (nanoceria) and a multimodal reporting nanoparticle component (i.e. Dex-IR-DiR). The device and system is utilized in treatment of diseases with a pro-inflammatory component, including, but not limited to, Crohn\u27s disease, ulcerative colitis, inflammatory bowel disease, cystic fibrosis, arthritis, and cancer chemotherapy
