PEGylated Gold Nanoprobe Bearing the Diselenide Bond for ROS-Responsive Fluorescence Imaging

Reactive oxygen species (ROS)-sensitive imaging can be used to distinguish ROS-rich diseased tissues from normal tissues. Herein, we developed a selective H2O2 concentration-dependent on-off gold nanoprobe and demonstrated its in vitro fluorescence imaging application using activated macrophages cells. The nanoprobe was prepared by covalent conjugation of polyethylene glycol and fluorescein dyes on gold nanoparticle surface through a H2O2-sensitive diselenide linker. The nanoprobes were well-dispersed in aqueous solution and inactive in H2O2-deficient conditions, ascribed to fluorescence resonance energy transfer between dye and gold nanoparticles. Once the nanoprobe was exposed to an H2O2-rich environment, it was quickly activated by diselenide bond dissociation, leading to fluorophore release from its surfaces. Overall, gold nanoprobe with the diselenide linker might be a potential candidate for ROS imaging.