A biosensor that utilizes carbon nanotubes functionalized with a protein sequence. One domain of the multifunctional peptide sequence noncovalently binds to the surface of single-walled carbon nanotubes (SWNTs), while a second domain of the sequence recognizes and binds to a target molecule. The sequence of the peptide may be tailored to allow it to recognize and bind to specific target molecules, such as chemicals, biological materials, and explosives. The binding of the target molecule to the peptide may alter a material property of the SWNTs.