One-step reactivity-driven synthesis of core–shell structured electrically conducting particles for biomedical applications

Abstract

Electrically conductive and functional polymeric nanoparticles have significant potential in biomedical applications such as in sensing and stimulation. Polymeric core–shell particles are usually prepared either through a multiple-step process or by the design of amphiphilic macromolecules. Here we report a simple one-step and one-pot emulsion polymerization method to synthesize the core–shell structured electrically conducting polymer particles based on the difference in comonomer reactivity. The morphology and the surface and bulk chemistry of poly(pyrrole-co-(1-(2-carboxyethyl)pyrrole)) (PPy-co-PPyCOOH) particles formed at different reaction times were analyzed by scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), Fourier transform infrared spectroscopy (FTIR), thermal gravimetric analysis (TGA) and total elemental analysis. The particles were found to be formed by a shell composed of the less conductive but functional PPyCOOH homopolymer, and a core made of the PPy dominated PPy-co-PPyCOOH copolymer of high conductivity. Human serum albumin antibody (anti-HSA) as a model molecule was covalently immobilized onto the particle surface and proven to be reactive to HSA. A five-step schema based on a novel reactivity-driven mechanism was proposed to explain the formation of the core–shell structure. This new strategy therefore provides a simple and general route to prepare core–shell conductive particles with a functional surface, based on the reactivity of comonomers.