Aptamer–field-effect transistors overcome Debye length limitations for small-molecule sensing

TLDR

Transistor sensing in salt solutions relies on changes in FET transconductance upon receptor binding, but the electrical double layer in saline media masks events within about 1 nm of the surface. The study aims to overcome Debye length limitations for small‑molecule sensing in high‑ionic‑strength solutions. This is achieved by using large, negatively charged DNA stem‑loop structures that undergo ligand‑induced conformational changes detectable by FET transconductance. The authors demonstrate detection of charged molecules such as dopamine in artificial cerebrospinal fluid, neutral molecules like glucose, and zwitterionic molecules such as sphingosine‑1‑phosphate. Published in Science, p.

Abstract

Transistor sensing in salt solutions Molecular binding to receptors on the surface of field-effect transistors (FETs) can be sensed through changes in transconductance. However, the saline solutions typically used with biomolecules create an electrical double layer that masks any events that occur within about 1 nanometer from the surface. Nakatsuka et al. overcame this limitation by using binding to large, negatively charged DNA stem loop structures that, upon ligand binding, cause conformational changes that can be sensed with an FET, even in solutions with high ionic strength. The authors demonstrate the sensing of charged molecules such as dopamine in artificial cerebrospinal fluid as well as neutral molecules such as glucose and zwitterion molecules like sphingosine-1-phosphate. Science , this issue p. 319