Nanotubes as mass sensors
doi:10.1038/nindia.2011.119 Published online 18 August 2011
Using computer-based models, researchers have shown that single-walled carbon nanotubes (CNTs) can be used to sense the mass of biomolecules such as amino acids. The mass-sensing ability of CNTs will be useful for detecting cancer biomarker molecules and disease-causing bacteria. Biomolecular mass detection is a new field of research that involves zeptogram measurements — roughly the mass of a single protein molecule.
Measuring such a small mass requires an extremely sensitive device. Preliminary studies have shown that CNTs could provide a sensitive scaffold to which biomolecules such as proteins and enzymes can be attached.
To examine the potential roles of CNTs as mass sensors, the researchers designed computer-based simulation studies in which eight molecules of alanine, an amino acid and five molecules of deoxyadenosine were attached to 50-nm-long single-walled CNTs.
The principle of mass detection using nanobiosensors such as CNTs is based on the fact that the resonant frequency of a CNT is very sensitive to the mass of the attached molecule. Changing the molecule causes a shift in the resonant frequency of the CNT; the mass of the attached molecule can therefore be detected by quantifying the shift in the resonant frequency.
The researchers observed a greater frequency shift for alanine than deoxyadenosine. The mass sensor offers extremely high resolution because it is based on an individual CNT. The researchers say that the device could be used to measure the masses of individual atoms such as chromium, gold and silver.
- Joshi, A. Y. et al. Zeptogram scale mass sensing using single walled carbon nanotube based biosensors. Sensor. Actuator. Phys. 168, 275-280 (2011) | Article |