Diamond nanowires modified with poly[3-(pyrrolyl)carboxylic acid] for the immobilization of histidine-tagged peptides

Coating boron-doped diamond nanowires (BDD NWs) with a conducting polymer, poly[3-(pyrrolyl)carboxylic acid], has been reported. Polymer coating was achieved through electropolymerization of 3-(pyrrolyl)carboxylic acid at the electrode interface by amperometrically biasing the BDD NWs interface until a predefined charge has passed. The poly[3-(pyrrolyl)carboxylic acid] modified BDD NWs (PPA–BDD NWs) were characterized by scanning electron microscopy (SEM) and cyclic voltammetry (CV). Using a deposition charge of 11 mC cm−2 resulted in a thin polymer film deposition. The availability of the carboxylic groups of the polymer coated BDD NWs electrode was demonstrated through copper ion (Cu2+) chelation. The resulting complex was successfully used for the site-specific immobilization of histidine-tagged peptides. The binding process was followed by electrochemical impedance spectroscopy (EIS). The Cu2+-chelated PPA–BDD NWs interface showed peptide loading capability comparable to those of commercially available interfaces and can be easily regenerated several times using ethylenediaminetetraacetic acid (EDTA).