Structured biotinylated poly(3,4-ethylenedioxypyrrole) electrodes for biochemical applications

The immobilization of biotin on transducer surfaces is a very important step for the fabrication of biosensors for many applications (immunoassay, DNA-hybridization assays, targeted imaging). Biotinylated polypyrroles have been studied and tested but gave rise to problems of polymerization and stability due to the intrinsic properties of pyrrole. As an alternative, biotinylated pyrroles were often used in a copolymerization with pyrrole or with an amphiphilic pyrrole derivative in a copolymerization to reduce the problems due to the pyrrole substitution. To find a new strategy, this paper presents the homopolymerization, instead of the use of a copolymerization, by replacing pyrrole by 3,4-ethylenedioxypyrrole bearing biotinylated substituent. We report the synthesis, characterization and electrochemical properties of two biotinylated 3,4-ethylenedioxypyrroles differing by the length of the alkyl spacer (ethyl or dodecyl) as well as the characterization of the corresponding polymer films. We successfully show, by cyclic voltammetry, that these monomers polymerize perfectly and give relatively stable polymer films. The increase of the alkyl spacer improves the polymerization and increases the polymer stability. For the first time, we also studied the surface morphology of an electrodeposited biotinylated polymer. The electrodeposition of these biotinylated derivatives gave rise to the ability to modulate the surface microstructuration, which consists of microspheres or cauliflower-like microstructures according to the length of the alkyl spacer.