Cationic conjugated polymer/heparin interpolyelectrolyte complexes for heparin quantification

A cationic conjugated polymer (P1) containing 20 mol-% 2,1,3- benzothiadiazole (BT) content is synthesized through a post-polymerization method. With a good water solubility (≈20mg.mL^-1), this polymer has shown a low inherent BT emission in aqueous solution. Formation of interpolyelectrolyte complexes between oppositely charged P1 and heparin facilitates energy transfer from the fluorene segments to the BT units within P1, leading to the intensity increase for the orange emission peak at 585nm and the intensity decrease for the blue emission at 412 nm. A practical calibration curve ranging from 0.2 to 76 × 10^-6 M is thus obtained by correlating the changes in BT emission with the heparin concentration in buffer. The significant advantage of this heparin macromolecular probe is that the calibration curve could cover the whole range of the therapeutic dosing level of heparin.