Chemiluminescence (CL) imaging has high sensitivity with significantly increased signal-to-background ratio due to no interferences of light source and autofluorescence. However, it is still a great challenge to design and synthesize a highly sensitive CL imaging probe that acquires intensive and long-lasting emission. Here, we demonstrate mimic-enzyme catalytic CL polymer dots (polystyrene (PS)–hemin dots) consisting of hemin, polystyrene, and amphiphilic polymer. CL emission catalyzed by PS–hemin dots increased tremendously, 6000-fold more than that of peroxide hydrogen–CL substrate direct reaction and over 5 h emission. These properties are mainly due to a large number of hemin molecules in a single nanoparticle, high-catalytic activity of PS–hemin dots and slow-diffusion-controlled heterogeneous reaction. PS–hemin dots also possess good stability, excellent biocompatibility, and ultrasensitive response to hydrogen peroxide. The conjugates of PS–hemin dots and integrin-targeting ligand cyclic RGD (arginine–glycine–aspartic) were used for CL imaging of normal and cancerous cells based on the specific reaction between the integrin αVβ3 and cyclic RGD. PS–hemin dots were also successfully used for real-time imaging reactive oxygen species levels in normal and inflammatory mice. PS–hemin dots as highly sensitive CL probes have great potential in bioassays and bioimaging.

Chemiluminescence (CL) systems have been used as excitation sources through chemiluminescence resonance energy transfer (CRET) between CL substrates and photosensitizers for photodynamic therapy (PDT). However, it is still a tremendous challenge to construct a highly effective CL system that has a strong emission intensity and long duration time for PDT. Here, we constructed a Fe­(III) deuteroporphyrin IX chloride-polymer dots (FeDP-Pdots) catalyzed CL system for cancer therapy, where the CL system was used as the generation of singlet oxygen for inhibiting and killing tumor cells with the use of FeDP-Pdots as both the catalysts and the photosensitizers. We prepared metalloporphyrin-polymer dots (M-Pdots) by nanoprecipitation and systematically investigated the relationship between the catalytic CL activities of M-Pdots and the structures of metalloporphyrins. It is found that FeDP-Pdots have the highest catalytic activity among 11 M-Pdots. Their CL intensity is almost 200-fold higher than the hemin-Pdots catalyzed system. The strong catalytic activity of FeDP is derived from its center ion Fe­(III), carboxyl groups, conjugated system, and smaller steric hindrance. Importantly, our results demonstrated that the higher the chemiluminescence intensity is, the more reactive oxygen species are produced during the Pdots catalyzed CL reaction. The FeDP-Pdots catalyzed luminol analogue L012-H2O2 CL system was used successfully for in vitro and in vivo cancer therapy. Our proposed method is characterized by the mass production of singlet oxygen through CRET and no requirement of light source. It is simple, selective, and effective, which develops a strong emission intensity and long-duration CL system for PDT and can be applied for the therapy of deep cancer tissues.