Synthesis of IrO(2)decorated core-shell PS@PPyNH(2)microspheres for bio-interface application

Abstract

In this paper, an effective approach is demonstrated for the fabrication of IrO2-decorated polystyrene@functionalized polypyrrole (core@shell; PS@PPyNH2) microspheres. The synthesis begins with the preparation of monodispersive PS microspheres with a diameter of 490 nm, by a process of emulsifier-free emulsion polymerization, followed by a copolymerization process involving pyrrole and PyNH(2)monomers in a PS microsphere aqueous suspension, to produce uniform PS@PPyNH(2)microspheres with a diameter of 536 nm. The loading of 2 nm IrO(2)nanoparticles onto the PS@PPyNH(2)microspheres can be easily adjusted by tuning the pH value of the IrO(2)colloidal solution and the PS@PPyNH(2)suspension. At pH 4, we successfully obtain IrO2-decorated PS@PPyNH(2)microspheres via electrostatic attraction and hydrogen bonding simultaneously between the negatively-charged IrO(2)nanoparticles and the positively-charged PS@PPyNH(2)microspheres. These IrO2-decorated PS@PPyNH(2)microspheres exhibit a characteristic cyclic voltammetric profile, similar to that of an IrO(2)thin film. The charge storage capacity is 5.19 mA cm(-2), a value almost five times greater than that of PS@PPyNH(2)microspheres. In addition, these IrO2-decorated PS@PPyNH(2)microspheres exhibit excellent cell viability and biocompatibility.