Synthesis, characterization and biomedical applications of functionalized polypyrrole-coated polystyrene latex particles

N-hydroxysuccinimide-functionalized polypyrrole (PPy-NHS) coated onto polystyrene (PS) latex particles were prepared by the in situ copolymerization of pyrrole and the active ester-functionalized pyrrole (pyrrole-NHS) in the presence of bare PS substrates. The initial comonomer concentration ratios were 25/75 and 50/50 for pyrrole and pyrrole-NHS, respectively. PS particles were prepared by two methods: emulsion polymerization, leading to particle sizes in the 450-500 nm range, and dispersion polymerization using poly(N-vinylpyrrolidone) (PNVP) as a steric stabilizer. The polypyrrole-coated PS particles (PS-PPy) were characterized in terms of particle size, surface charge and surface chemical composition. For the "emulsion" PS coated with polypyrrole, the particles were evaluated as bioadsorbents of human serum albumin (HSA). It is believed that the proteins attach themselves by covalent bonds at the surfaces of NHS-functionalized PPy-PS particles. It is shown that the maximum adsorption levels off at 0.2 mg/m² in the case of the 50/50 initial ratio concentration but only to 0.02 mg/m² in the case of the 25/75 ratio, an indication that a higher concentration of surface reactive groups hamper the covalent attachment of HSA at the surfaces of polypyrrole particles.