LAUSR

Ionic polythiophenes are important conjugated polymers because of their excellent optical properties and water solubility. They are classified as cationic, anionic and zwitterionic conjugated polyelectrolytes. This review article describes concisely their biological and analytical applications. The specific detection of different negatively charged biomolecules such as DNA and adenosine triphosphate, anions like halides and toxic pseudo-halide (CN−) and environmental pollutants, e.g. surfactants, is discussed. The conformational changes of cationic polythiophenes (CPTs) induced by various analytes due to formation of ionic conjugates and the cooperative responses of all segments cause dominant signal amplification even in the presence of a small perturbation. In addition, reactive oxygen scavenging, antimicrobial photosensitizing and cell imaging applications of CPTs are documented. Use of anionic polythiophenes for sensing of protamine and cations like Cu2+ and Ca2+ is also discussed. Finally, sensing of DNA, peptides and surfactants by zwitterionic polythiophenes is included. The concluding part discusses future prospects. © 2016 Society of Chemical Industry