An easy and rapid detection of hazardous compounds is crucial for making on-the-spot irreversible decisions at airport security gates, luggage storage rooms, and other crowded public places, such as stadia, concert halls, etc. In the present study we carried out a preliminary investigation into the possibility of utilizing as advanced nano-biosensors a mutant form of the bovine odorant-binding protein (bOBP) immobilized onto carbon nanotubes. In particular, after immobilization of the protein on the carbon nanotubes we developed a competitive resonance energy transfer (RET) assay between the protein tryptophan residues located at the positions 17 and 133 (W17 and W133) and the 1-amino-anthracene (AMA), a molecule that fits in the binding site of bOBP. The bOBP-AMA complex emitted light in the visible region upon excitation of the Trp donors. However, the addition of an odorant molecule to the bOBP-AMA complex displaced AMA from the binding site making the carbon nanotubes colorless. The results presented in this work are very promising for the realization of a color on/ color off b-OBP-based biosensor for the initial indication of hazardous compounds in the environment.