Enzyme-Coated Carbon Nanotubes as Single-Molecule Biosensors

TLDR

The study demonstrates that individual semiconducting single‑wall carbon nanotubes can serve as versatile biosensors. The sensor is fabricated by covalently attaching glucose oxidase to the nanotube sidewall via a linker, producing a measurable conductance change. The enzyme‑coated nanotube functions as a reversible pH sensor and detects glucose through a stepwise conductance change, demonstrating single‑nanotube enzymatic activity and offering a new platform for biomolecular diagnostics.

Abstract

We demonstrate the use of individual semiconducting single-wall carbon nanotubes as versatile biosensors. Controlled attachment of the redox enzyme glucose oxidase (GOx) to the nanotube sidewall is achieved through a linking molecule and is found to induce a clear change of the conductance. The enzyme-coated tube is found to act as a pH sensor with large and reversible changes in conductance upon changes in pH. Upon addition of glucose, the substrate of GOx, a steplike response can be monitored in real time, indicating that our sensor is also capable of measuring enzymatic activity at the level of a single nanotube. This first demonstration of nanotube-based biosensors provides a new tool for enzymatic studies and opens the way to biomolecular diagnostics.