Cyclic voltammograms of the HRP-AuNCs/SWCNTs/CFUME (A), HRP/SWCNTs/CFUME (B), SWCNTs/CFUME (C), HRP-AuNCs/CFUME (D), HRP/CFUME (E) and CFUME (F) in 0.01 M pH 7.0 deoxygenated PBS in the absence of H2O2 (a) and presence of 0.01 mM (b) and 0.03 mM (c). Scan rate =100 mV/s.

<p>In order to explore the electrocatalytic activity of HRP on the modified electrode, its response to the reduction of H₂O₂ was studied. As shown in F.S2, with the addition of H₂O₂, the electrochemical behavior of HRP-AuNCs immobilized electrode changes dramatically. The reduction peak current increases obviously, while the oxidation peak current decreases with increasing the concentration of H₂O₂ (F.S2 A), showing a typical electrocatalytic reduction process of H₂O₂. However, no similar cathodic peak corresponding to the reduction of H₂O₂ can be observed at HRP/MWCNTs/CFUME (B), MWCNTs/CFUME (C), HRP-AuNCs/CFUME (D), HRP/CFUME (E) and bare CFUME (F). These results indicate AuNCs synthesized in HRP can effectively promote electron transfer between enzyme and electrode, which can give the ideal performance for reduction based H₂O₂ detection.</p>