RESUMEN
We have investigated the electrical transports of double-walled carbon nanotube field effect transistors (DWNT-FETs) with modified contacts. The CNT/Au metal contacts of DWNT-FETs were modified with a self-assembled monolayer of 2-aminoethanethiol molecules. In ambient air, the contact-modified DWNT-FETs showed a decreased conductance in the p-channel (negative gate voltages) and an increased conductance in the n-channel (positive gate voltages), while the original device showed p-type transport. In a vacuum, the n-channel current in the contact-modified DWNT-FET started to rise. We observed a clear n-type transport in the high vacuum. Almost no changes in the gate threshold voltages were observed by means of the contact-modification with a self-assembled monolayer. While the semiconducting DWNT-FET showed a clear transition from a p-type to n-type transistor with contact modification, no apparent changes were observed in semi-metallic DWNT devices.
RESUMEN
We report the real-time detection of protein using SWNT-FET-based biosensors comprising DNA aptamers as molecular recognition elements. Anti-thrombin aptamers that are highly specific to serine protein thrombin were immobilized on the sidewall of a SWNT-FET using CDI-Tween linking molecules. The binding of thrombin aptamers to SWNT-FETs causes a rightward shift of the threshold gate voltages, presumably due to the negatively charged backbone of the DNA aptamers. While the addition of thrombin solution causes an abrupt decrease in the conductance of the thrombin aptamer immobilized SWNT-FET, no noticeable change was observed with elastase.