A novel scanning electrochemical/chemiluminescence microscopy (SECM/SCLM) was 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 luminol solution, the immobilized HRP catalyzed the oxidation of luminol by the electrogenerated H2O2 at the tip to emit chemiluminescence which was detected by a photon-counter. The photon-counting intensity was plotted against the position of the tip to give the image indicating the activity of immobilized HRP. The topography image was also obtained by mapping the oxygen reduction current, since the current was sensitive to the topography of substrate.
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