Nanobiosensors: the most recent nanotechnological "noses"

Nanobiosensors certainly have their place in the futuristic universe of the nanotechnologies. The latest generation of electronic noses are nanobiosensor arrays based on the electrical properties of olfactory receptors from mammals, which are proteins situated in the olfactory epithelium within the nasal cavities.

To design this novel, artificial biosensor system, the researchers used the physical reactions which occur in animals when an odorant molecule is detected by an olfactory receptor. They thus induced yeast cells to express olfactory receptors from mammals (rat and human). The nanobiosensors were produced by grafting these specific proteins, carried by nanovesicles, between two nanoelectrodes.

When an odorant molecule binds to the olfactory receptor, this causes a conformational change and modifications to the impedancemetric properties of the protein, which are recorded via nanoelectrodes.
The INRA researchers and European consortium have thus shown that the modifications observed to the receptors carried by these nanovesicles do indeed result from the specific behaviour of the olfactory receptor in response to odorant stimulation. The tests also showed that the nanobiosensors reacted to a very small amount of odorant molecules (high level of sensitivity) with a considerable degree of precision (high specificity).

Nanobiosensors are thus capable of detecting odours at levels which may be imperceptible to the human nose.

To develop a bioelectronic nose capable of detecting and identifying a wide variety of odours, the researchers can use yeast cells capable of producing a broad range of different olfactory receptors from the rat or dog (both species are endowed with more than a thousand different receptors). Combining the responses of these receptors should make it possible to detect practically any odour presented.

In parallel with laboratory analyses of the functional response of olfactory receptors, the researchers have been working with their partners on developing the instrumentation and data processing tools necessary to design a true nano-bio-electronic nose at an industrial scale.

The potential applications are numerous and promising: food safety and quality control (toxic compounds, degradation, purity), cosmetics, protection of the environment (air and water quality, contaminants, smoke analysis), on-line monitoring of industrial or environmental processes (ripening, fermentation), safety controls (detection of dangerous or toxic substances, explosives, drugs), as an aid when searching for buried victims, medical diagnostics (diabetes, schizophrenia, cancer, etc.), etc.

SPOT NOSED has been funded by the European Union in the context of the FET (Future and Emerging Technologies) programme.
 

• Vidic, J.M. et al. Quantitative assessment of olfactory receptors activity in immobilized nanosomes: a novel concept for bioelectronic nose. Lab Chip 6, 1026-1032 (2006).

• Hou, Y. et al. A novel detection strategy for odorant molecules based on controlled bioengineering of rat olfactory receptor I7. Biosens Bioelectron (2006).

• Gomila, G., Casuso, I., Errachid, A., Ruiz, O., Pajot, E., Minic, J., Gorojankina, T., Persuy, M.A., Aioun, J., Salesse, R., Bausells, J., Villaneuva, G., Rius, G., Hou, Y., Jaffrezic, N., Pennetta, C., Alfinito, E., Akimov, V., Reggiani, L., Ferrare, G., Fumagalli, L., Sampietro, M., Samitier, J. Advances in the production, immobilization, and electrical characterization of olfactory receptors for olfactory nanobiosensor development. Sensor actuat B-chem 116, 66-71 (2006).