Polypyrrole functionalized with new copper complex as platform for His-tag antibody immobilization and direct antigen detection

A biomaterial based on a copper complex covalently attached to a polypyrrole backbone was designed for monitoring a glycoprotein, D-dimer, used as a marker of the deep vein thrombosis (DVT) condition. For this purpose a new copper complex has been developed based on the ligand N-(2-hydroxybenzyl)-N′-(6-aminohexyl)-N,N′-bis[2-(N-methylimidazolyl)methyl]ethane-1,2-diamine (3) that is able to coordinate copper ions through two imidazole, two amine and one phenolato moieties—this coordination sphere will be labeled enPI2. The complex conjugated with a polypyrrole layer allows the His-tag antibody immobilization onto the conducting polymer substrate and immunosensor evaluation. The biomaterial shows a remarkable variation in redox activity of the Cu(II) complex after the D-dimer interaction. The redox activity of the [(enPi2)Cu(II)] complex decreases after the antigen interaction providing a linear response between 0.01 and 500 ng mL−1 with a detection limit of 10 pg mL−1. The chemical structure of copper complex demonstrates the ability to avoid non specific-interaction leading to anti fouling surface. Such biolayer architecture offers high measurement stability over time and the biomaterial could be stocked for several weeks without any modification of the electrochemical properties.