Direct electron transfer (DET) from biomolecules to electrode is a process without electron-mediators, thus superior selectivity and sensitivity is expected in order to monitor electron transfer between electrode and biomolecules without any mediator interference. However, DET is difficult because a redox center which is an electron active center of proteins such as enzymes is buried deep. So, a unique electrode nanostructure to reach the redox center is a critical factor. Here we have systematically investigated terms for DET using various nanofiliformed electrode morphologies and enzyme concentrations. It is pointed out that the reaction site is below 100nm, the ration amounts of adsorbed enzyme per surface area are below 1.0 are contributed to the DET. As a great application, we have developed a biosensor monitoring the hydrogen peroxide (H2O2) detecting capability from peroxidase directly. For the fabricated HRP/nTOF/Ti-electrodes observed the catalytic current value was linear according to the increase in the concentration of H2O2 up to 100μM, which indicates a good potential for an H2O2 biosensor.
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