Synthesis of a novel water-soluble conjugated polyelectrolyte based on polycyclopentadithiophene backbone and its application for heparin detection, Designed Monomers and Polymers, 17:7, 624-628,The novel water-soluble conjugated polyelectrolyte containing a new kind of backbone poly [(4,4-bis(3ʹ-N,N,N-trimethylammonium) propyl) cyclopentadithiophene dichloride] (PBTPC-Cl) is synthesized and characterized. The PBTPC-Cl is readily soluble in polar solvents and is applied as a sensitive and selective fluorescent probe for heparin detection in aqueous solution. Upon adding heparin into the aqueous solution of polymer, PBTPC-Cl could bind heparin via electrostatic interactions and results in the quenching of emission peaks. Quantitative analysis of heparin shows high selectivity and good linear relationship with a detection limit to 0.05 μM in HEPES aqueous buffer.