For whole animal in-situ and real-time imaging of inflammation, a dual-color fluorescent nanoprobe is provided for the detection of reactive oxygen and nitrogen species (RONS) in inflammatory microenvironments. The nanoprobes of the disclosure are a RONS-responsive energy transferring nanosystem of a fluorescent conjugated polymer core and a PEG-shell linked with RONS-sensing antennae as a FRET acceptor. These nanoprobes allow in vivo imaging of the entire process of inflammation from the release of local tissue distress signals, to the action of leukocytes and macrophages late in the process of inflammation, through to restitution, allowing in whole-body diagnosis and monitoring of inflammatory diseases.