Tunneling-based biosensor detects tens of DNA molecules per liter in smaller form factor
DOI: 10.1063/10.0005506
Tunneling-based biosensor detects tens of DNA molecules per liter in smaller form factor lead image
The push to make medical diagnostics suitable for high-speed, point-of-care applications has called for renewed interest in sensing the electrochemical properties of biomolecules. A DNA biosensor looks to deliver long sought smaller form factor with the sensitivity to detect pathologies ranging from infections to cancer.
Researchers revealed a tunneling current biosensor that features a design which is sensitive enough to detect DNA at a concentration of one quintillionth of a mole. The sensor takes advantage of metal-insulator-electrolyte junctions, which are highly sensitive to charge variations at the insulator-electrolyte interface.
“If the gap between two wires is on the order of few tens of nanometers, we can create a very small current due to electrons ‘tunneling across’ the gap,” said author H. Kumar Wickramasinghe. “As charge builds up on the surface of the electrolyte/aluminum oxide interface due to DNA attachment, we detect an increase in tunnel current across the oxide film.”
Most DNA and protein sensors rely on field-effect transistor geometry whose three-terminal design require relatively bulky devices.
The group’s two-terminal sensor relies on the log-linear relationship between current and voltage across tunneling oxides for its high sensitivity. The group developed high-integrity, nanoscale aluminum oxide films that can detect the small changes in current encountered during the biomolecular recognition techniques commonly used in diagnostics.
The resulting approach has allowed Wickramasinghe and his colleagues to detect DNA at concentrations of tens of molecules per liter, without the need for labels.
Wickramasinghe hopes the work inspires others to explore chemical properties of biomolecules for rapid diagnostics. He looks to integrate the sensor with existing polymerase chain reaction technology.
Source: “Tunneling based ten attomolar DNA biosensor,” by Z. Mardy, Y. L. Tao, L. A. Renna, S. Ardo, and H. K. Wickramasinghe, AIP Advances (2021). The article can be accessed at https://doi.org/10.1063/5.0046458 .
