Electrical detection of hybridization and threading intercalation of deoxyribonucleic acid using carbon nanotube network field-effect transistors

The authors study deoxyribonucleic acid (DNA) sensing characteristics of carbon nanotube network field-effect transistors (CNNFETs) by monitoring their electrical responses upon immobilization with a DNA probe, hybridization with DNA analytes, and intercalation with a N,N^′-bis(3-propylimidazole)-1,4,5,8-naphthalene diimide modified with Os(2,2^′-bipyridine)₂Cl⁺ pendants. The CNNFETs immobilized by single-stranded DNA molecules demonstrate the selective sensing of its complementary and single-base mismatched DNA (difference of ∼16% in reduction of normalized drain current I_d). Subsequent intercalation demonstrates a further sensitivity enhancement (difference of ∼13% in I_d reduction) due to specific binding between hybridized DNA and intercalators, corroborated by the x-ray photoelectron spectroscopy study.