Polypyrrole-coated polystyrene latex particles bearing reactive N-succinimidyl ester functional groups (PS-PPyNSE75) were prepared by the in situ copolymerization of pyrrole 1 and the active N-succinimidyl ester-functionalized pyrrole 2 (pyrroleNSE), with initial 1:2 fractions of 25:75 (%) in the presence of sterically stabilized polystyrene (PS) latex particles. PS particles were prepared by dispersion polymerization leading to particles having a diameter of 600 +/- 10 nm. The PS-PPyNSE75 particles were characterized in terms of surface morphology and chemical composition. Surface analysis of the colloidal materials by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) indicated a substantial coating of PS by the reactive conducting copolymer. Infrared spectroscopy permitted to detect pyrroleNSE repeat units at the surface of the particles indicating that 1 and 2 did indeed copolymerise. Reactivity of the PS-PPyNSE75 particles has been investigated using 2-aminoethanol and 2-mercaptoethanol, two model molecules bearing functional groups borne by proteins. Incubation of the particles with these model molecules clearly showed that the particles are highly reactive towards amine and thiol groups. The functionalized particles were then tested as bioadsorbents. PS-PPyNSE75 particles were found to be effective in attaching an aminated biotin. The Biotin-decorated PS-PPyNSE75 latex particles were incubated with avidin with a result of a significant change in the surface composition that is in line with the attachment of the protein by specific binding to biotin. (C) 2004 Elsevier Ltd. All rights reserved.