The work addresses some key issues regarding the adaptation of carbon nanotubes to electronic biodetection. We present a robust scheme for the functionalization of carbon nanotubes by Tween 20 in bulk solution and on substrates, which not only facilitates subsequent immobilization of protein receptors onto the nanotube surface, but also provides a measure of non-specific binding resistance to proteins.

The key discovery here is the efficient functionalization of carbon nanotubes by surfactant systems. This enables not only the solubilization of bulk nanotubes in solution, but also a self-assembled coating on the surface of nanotube devices that can be easily conjugated to protein receptors, while simultaneously affording resistance to non-specific binding.

Carbon nanotube devices had been demonstrated by others in our group to be extremely sensitive gas-phase chemical detectors. Extending this capability to the solution phase, specifically for the detection of biomolecules, was a natural direction, motivated by the need for extremely sensitive real-time assays for specific protein-binding detection.

Carbon nanotubes have been integrated into electronic devices for the detection of biomolecules in solution. Current techniques rely on pre-labeling with fluorescent dye in order to visualize detection. Our devices obviate this step, being able to detect specific binding events on the surface instantaneously and with comparable sensitivity.