Area-selective Immobilization of Multi Enzymes by Using the Reductive Desorption of Self-assembled Monolayer

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The immobilization of two enzymes on a pair of Au microband electrodes was performed by using electrochemical desorption of self-assembled monolayer (SAM) of alkanethiol. Both of the Au electrodes were coated with the SAM of n-octadecanethiol (ODT-SAM) at first. The ODT-SAM on one of the Au electrodes was electrochemically removed by applying reductive potential. The resulting naked Au surface was re-coated with the SAM of 2-aminoethanethiol (AET). These treatments resulted in a couple of Au electrodes coated with the ODT-SAM and AET-SAM, respectively. Horseradish peroxidase (HRP) was selectively immobilized on the AET-SAM by using crosslinking agent, glutaraldehyde. On the other hand, diaphorase (Dp) was immobilized on the surface of ODT-SAM by hydrophobic interaction. The imaging of the resulting substrate with scanning electrochemical microscope (SECM) demonstrated the enzymatic activities of HRP and Dp at the AET- and ODT- treated Au electrodes, respectively.