Imaging the activity of immobilized horse radish peroxidase with scanning electrochemical/chemiluminescence microscopy

A novel scanning electrochemical/chemiluminescence microscopy (SECM/SCLM) w as used for imaging of a spot of immobilized horse radish peroxidase (HRP) on a substrate. When the SECM tip scanned over the spot in an aqueous lumin ol solution, the immobilized HRP catalyzed the oxidation of luminol by the electrogenerated H2O2 at the tip to emit chemiluminescence which was detect ed by a photon-counter. The photon-counting intensity was plotted against t he position of the tip to give the image indicating the activity of immobil ized HRP. The topography image was also obtained by mapping the oxygen redu ction current, since the current was sensitive to the topography of substra te.