Enhanced enzyme activity through electron transfer between single-walled carbon nanotubes and horseradish peroxidase.

Better understanding of electron transfer (ET) taking place at the nano-bio interface can guide design of more effective functional materials used in fuel cells, biosensors, and medical devices. Single-walled carbon nanotube (SWCNT) coupled with biological enzymes serves as a model system for studying the ET mechanism, as demonstrated in the present study. SWCNT enhanced the activity of horseradish peroxidase (HRP) in the solution-based redox reaction by binding to HRP at a site proximate to the enzyme's activity center and participating in the ET process. ET to and from SWCNT was clearly observable using near-infrared spectroscopy. The capability of SWCNT in receiving electrons and the direct attachment of HRP to the surface of SWCNT strongly affected the enzyme activity due to the direct involvement of SWCNT in ET.