Due to the high stability and outstanding electrochemical properties, the conductive polypyrrole has been become the research focus as the sensitive layer of protein sensors. In the present work, the conductive pyrrole copolymer films functionalized by carboxyl and amino groups were prepared via the oxidative polymerization. The chemical compositions of the copolymers could be adjusted by varying the monomer ratios. Fourier transform infrared spectroscopy was employed to determine the chemical composition of copolymer. While the electrochemical properties of such copolymer film was measured by cyclic voltammetry. On these bases, the adsorption kinetics of bovine serum albumin (BSA) onto the copolymer surface was in situ investigated by surface plasmon resonance of spectroscopy. The differences among the adsorption kinetics and the adsorbed amounts of BSA depended mainly on the type and content of the functional group in the copolymer. It demonstrates that BSA prefers to adsorb onto the polymer surface with higher content of amino groups and lower content of carboxyl groups. Moreover, the adsorbed amount of BSA increased with the increase of amino content in polymer film. On the contrary, it decreases with the increase in carboxyl content in polymer film. Therefore, the adsorption behavior of proteins onto the conductive polymers could be controlled in this way. Furthermore, it could be used to fabricate the more sensitive and controllable protein sensors.

Key words: bovine serum albumin, conductive pyrrole copolymer, cyclic voltammetry, surface plasmon resonance of spectroscopy, protein adsorption