Polythiophenes -mediated polymerization

Polythiophenes functionalized with monosaccharides have been evaluated for their ability to detect the influenza virus and E. coli (Baek et al. 2000). Copolymers of thiophene acetic acid 10 and carbohydrate-modified thiophenes 11 have been prepared via iron(III) chloride mediated polymerization. Addition of influenza virus to a sialic acid containing copolymer resulted in a blue shift of the polymer absorption maximum, resulting in an orange to red chromatic transition. Mannose-containing polythiophenes underwent color changes upon the addition of the lectin ConA or E. coli cells that contain cell surface mannose-binding receptors. A similar biotinylated pol5hhiophene afforded a streptavidin responsive material (Paid and Leclerc 1996). 

M. C. lovu, C. R. Craley, M. Jeffries-EL, A. B. Krankowski, R. Zhang, T. Kowalewski, R. D. McCullough, Conducting Regioregular Polythiophene Block Copolymer Nanofibrils Synthesized by Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) and Nitroxide Mediated Polymerization (NMP). Macromolecules 2007,40,4733-4735. 

RAFT polymerization or nitroxide-mediated polymerization (NMP) was used instead of ATRP for the synthesis of the block copolymer of polythiophene and polyisoprene or polystyrene, because ATRP generates materials containing traces of metals from the catalyst [146]. A block copolymer of P3HT and poly (perylene bisimide acrylate) was also synthesized by NMP from a polythiophene macroinitiator (Scheme 51) [147, 148]. This block copolymer is a crystalline-crystalline donor-acceptor block copolymer and shows microphase separation, implying efficient photovoltaic applications. A similar polythiophene macroinitiator for NMP was used for the synthesis of fullerene-grafted rod-coil block copolymers [149]. 

Scheme 51 Synthesis of block copolymer of P3HT and poly(perylene bisimide acrylate) by nitroxide-mediated polymerization from polythiophene macroinitiator...

Conducting polymer-based immobilization or wired enzymes is a global enzyme immobilization method that differs in many respects from those just described. In one example, a redox polymer is formed on the surface by the oxidation of pyrrole molecules to pyrrole radical cations, which then polymerize on the surface to form conductive polypyrrole [60,68]. Other conducting polymers include polyvinylpyridine, polythiophene, polyaniline, and polyindole. If enzymes are present in the solution as polymerization takes place, they are entrapped within the polymer. When these polymers are cross-linked with redox mediators such as [Os(bpy)2Cl]+ 2 the resulting amperometric (or potentiomet-ric) biosensors are referred to as wired enzyme electrodes [5-7]. The distance between the redox centers of the polymer and the FADH2 centers of the reduced enzyme is reduced sufficiently for electrons to be transferred and, therefore, for the mediated electro-oxidation of glucose on conventional electrodes. These electrodes do not require diffusing redox mediators or membranes to contain the enzyme and the redox polymer. 

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