A regulatable gap-electrical DNA sensor based on gold nanorods and single-walled carbon nanotubes

• AuNRs can be arranged in an orderly manner along the SWCNTs. • AuNRs@SWCNTs device responses to the target DNA. • Different detection limits can be obtained by adjusting the electrode gap. • The detection effect is best in the 0.25 μm electrode gap, and the detection limit of target DNA reaches 1 pM. Infectious diseases, genetic diseases, and malignant tumor diseases are all related to DNA, but simple, unlabeled, and sensitive devices to detect DNA remain challenging. Carbon nanotubes biosensor has the advantages of low cost, fast detection speed, small size, and good biocompatibility. A new strategy gap device for DNA detection by using gold nanorods assembled in single-walled carbon nanotubes (AuNRs@SWCNTs) was developed. The AuNRs are synthesized with an average diameter of 56 ± 4.8 nm and a length of 95 ± 9.4 nm. Because of the anisotropic physical interaction between AuNRs and SWCNTs structure, when the SWCNTs grow on the surface of SiO 2 /Si substrate, the AuNRs are self-assembled orderly. The detection principle is based on the target DNA desorbing the probe DNA on the AuNRs to change its catalytic activity. The AuNRs are connected into nanowires along with the growth of the SWCNTs, thereby generating a conductance response. By adjusting the electrode gap, different detection limits were obtained. The 0.25 μm electrode gap device detected target DNA with the detection limit of 1 pM.