Polydopamine-Coated Solid Silica Nanoparticles Encapsulating IR-783 Dyes: Synthesis and NIR Fluorescent Cell Imaging

Abstract

We report a simple and efficient synthetic method for polydopamine (PDA)-coated solid silica nanoparticles (s-SiO 2 @PDA NPs) encapsulating anionic near-infrared (NIR) fluorescent dyes through physical adsorption. Despite the use of anionic NIR fluorescent dyes indocyanine green (ICG) and 2-), they were successfully immobilized on anionic s-SiO 2 @PDA NP surfaces under acidic aqueous conditions. After embedding in the s-SiO 2 @PDA NPs, the fluorescence of ICG was almost quenched, while a diminished IR-783 fluorescence remained observable. The fluorescence intensity of IR-783 embedded in s-SiO 2 @PDA NPs remained almost constant over 2 weeks in a pseudobiological solution, with a slight reduction due to dye degradation and dye leakage from the s-SiO 2 @PDA NPs. Finally, the s-SiO 2 @PDA NPs encapsulating IR-783 were successfully used for NIR fluorescent imaging of African green monkey kidney cells.