The influence of carbon-oxygen surface functional groups of carbon electrodes on the electrochemical reduction of hemoglobin
2017
Tom, Justin | Andreas, Heather A.
The electron transfer between a carbon electrode and hemoglobin in solution is known to be a slow and difficult process, likely due to the difficulty in accessing the redox active heme groups of hemoglobin. Literature data are inconsistent regarding electrochemical activity of hemoglobin on carbon electrodes and whether carbon-oxygen-containing surface functional groups enhance or inhibit the electroactivity of hemoglobin. Herein we examine the role of carbon surface functionalities in hemoglobin-electroactivity through cyclic voltammetry and differential pulse voltammetry in a neutral phosphate buffered electrolyte. Oxygen-containing surface functionalities were tracked ex situ using temperature programmed desorption, X-ray photoelectron spectroscopy and attenuated total reflectance Fourier transform infrared spectroscopy. Hemoglobin electroactivity is inhibited by ether and carbonyl surface groups present on the carbon electrode. A carbon material which showed little hemoglobin electroactivity was made more active through ultrasonication and electrochemical reduction, related to the removal of ether and carbonyl groups from the carbon surface. This known surface modification is quick, easy to implement, and avoids contamination from the use of additional reagents. The knowledge of carbon-oxygen surface functionalities is essential to better understand hemoglobin's electroactivity on carbon and influences the choice of carbon electrode materials for further development of hemoglobin electrochemical biosensors.
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