Micropatterning of active enzyme with a high-resolution by scanning electrochemical microscopy coupled with a nanometer-sized carbon fiber disk tip

We developed a new method for fabrication of nanometer-sized carbon fiber disk electrodes and applied them to micropattern active horseradish peroxidase (HRP) with a high-resolution by scanning electrochemical microscopy (SECM). In order to pattern active HRP, except for active HRP micropatterns predesigned other regions on a HRP-immobilized substrate was deactivated by a reactive species generated at the electrode as the tip of SECM held at 1.7 V through oxidation of Br− in 0.20 mol/L phosphate buffer (PB) containing 2.5 × 10−2 mol/L KBr and 2.0 × 10−3 mol/L BQ (pH 7.0). The micropatterns of active HRP were characterized using the feedback mode of SECM in PB containing 2.0 × 10−3 mol/L BQ and 2.0 × 10−3 mol/L H2O2, when the tip potential was held at −0.2 V.