Polystyrene–Hemin Dots for Chemiluminescence Imaging

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.