The development of reliable and reproducible chemistries for the immobilization of biomolecules to a conducting polymer is a key challenge in the design and preparation of a CP-based biosensor. In this article, the syntheses and electro-polymerization of a series of new 3-alkylthiophene derivatives functionalized with the most used reactive groups in immobilization chemistry, including maleimide, azide, and anhydride, are described. Despite the nucleophilic or electrophilic nature of the reactive groups, the synthesized thiophene monomers exhibit rather good polymerizability, and the reactive groups withstand the polymerization conditions and are correctly incorporated into the resulting electroactive polymers. The reactivity of the pendant reactive groups of the resulting polymers to attach biomolecules has been examined with different redox-active, photoactive compounds as well as recognition elements as model compounds. It has been confirmed that with well-established procedures developed for the immobilization of enzymes, the model compounds can be easily and selectively bound onto these new conducting polymers without the loss of their optical and electrochemical activity. Therefore, these conductive materials with a broad spectrum of reactive groups will provide a useful platform for developing CP-based biosensors for a wide range of applications. (c) 2005 Wiley Periodicals, Inc.