Synthesis of IrO decorated core-shell PS@PPyNH microspheres for bio-interface application.

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