The dynamic Schiff base bond is exploited to construct monodisperse dopamine-based nanoparticles with autofluorescence and pH-sensitivity. This allows facile monitoring and pH-responsive drug release in the acidic tumor microenvironment. Anticancer drugs doxorubicin and a photosensitizer chlorin e6 are further loaded into the nanoparticles and synergistic anticancer efficacy is achieved.