Carbon-nanotube field-effect transistors for resolving single-molecule aptamer-ligand binding kinetics

Nat Nanotechnol. 2024 May;19(5):660-667. doi: 10.1038/s41565-023-01591-0. Epub 2024 Jan 17.

Abstract

Small molecules such as neurotransmitters are critical for biochemical functions in living systems. While conventional ultraviolet-visible spectroscopy and mass spectrometry lack portability and are unsuitable for time-resolved measurements in situ, techniques such as amperometry and traditional field-effect detection require a large ensemble of molecules to reach detectable signal levels. Here we demonstrate the potential of carbon-nanotube-based single-molecule field-effect transistors (smFETs), which can detect the charge on a single molecule, as a new platform for recognizing and assaying small molecules. smFETs are formed by the covalent attachment of a probe molecule, in our case a DNA aptamer, to a carbon nanotube. Conformation changes on binding are manifest as discrete changes in the nanotube electrical conductance. By monitoring the kinetics of conformational changes in a binding aptamer, we show that smFETs can detect and quantify serotonin at the single-molecule level, providing unique insights into the dynamics of the aptamer-ligand system. In particular, we show the involvement of G-quadruplex formation and the disruption of the native hairpin structure in the conformational changes of the serotonin-aptamer complex. The smFET is a label-free approach to analysing molecular interactions at the single-molecule level with high temporal resolution, providing additional insights into complex biological processes.

MeSH terms

  • Aptamers, Nucleotide* / chemistry
  • Biosensing Techniques / instrumentation
  • Biosensing Techniques / methods
  • Kinetics
  • Ligands
  • Nanotubes, Carbon* / chemistry
  • Serotonin* / chemistry
  • Serotonin* / metabolism
  • Transistors, Electronic*