Low-temperature supercritical activation enables high-performance detection of cell-free DNA by all-carbon-nanotube transistor

Biosensors based on carbon nanotube (CNT) thin-film transistors (TFTs) have drawn intense interests for their exhibiting great potential in ultrasensitive and label-free DNA detection. However, the inevitable defects in the dielectric and channel of CNT-based TFTs may induce noisy or unreliable output signals. Here, we propose a low-temperature supercritical carbon dioxide (SCCO 2 ) fluid activation method to enhance the performance of transistor-based biosensors. An activation model of SCCO 2 treatment is proposed to elaborate that the SCCO 2 treatment can repair the dangling bonds of SiO 2 dielectric facilely and passivate the hydroxyl groups effectively. Furthermore, a cell-free DNA detection platform is built up based on all-carbon-nanotube TFTs (AC-TFTs) modified by the CW-Peptide probe. By adopting the SCCO 2 treatment, the response of AC-TFT biosensors to AKT2 gene related to triple-metastatic negative breast cancer can be enhanced by more than 114% with high uniformity, and a broad detection range of six orders of magnitude is yielded with a theoretical limit of detection of 42 fM. Additionally, the response has a linear correlation with the length of DNA targets. The nondestructive and eco-friendly SCCO 2 activation method provides a promising and universal strategy for achieving highly accurate and sensitive transistor-based biosensors in future clinical applications.