Electrical Detection of Femtomolar DNA via Gold‐Nanoparticle Enhancement in Carbon‐Nanotube‐Network Field‐Effect Transistors

Abstract

The development of sequence-selective DNA sensors for diagnosis of genetic or pathogenic disease has attracted increasing interest. Most DNA detection methods rely on optical, piezoelectric, or electrochemical transductions. Alternative methods based on the resistance change of a single silicon nanowire or an individual carbon nanotube have been reported. However, these sensors may have significant deviceto-device variations and their fabrication requires high production costs. Recently, field-effect transistors (FETs) based on single-walled carbon nanotube (SWNT) networks have been fabricated, and their electrical properties depend on the percolation paths of SWNTs in conduction channels, where device variations are expected to be small. Label-free electrical detection of DNA and biomolecules using SWNT network FETs (SNFETs) has been successfully achieved, with typical detection limits on the order of ca. 1 nM of DNA. In this Communication, we report that the detection sensitivity of SNFETs for DNA can be further improved to ca. 100 fM by using a ‘‘nanoparticle enhancement’’ approach, in which the target DNAs are hybridized with probe DNAs on the device, and reporter DNAs labeled with Au nanoparticles (AuNPs) flank a segment of the target DNA sequence. We note that the enhancement of DNA detection by incorporating nanoparticles (e.g., CdS and Au) has been recently reported by using electrochemical approaches. On