Horizontally Aligned Carbon Nanotube Based Biosensors for Protein Detection

A novel horizontally aligned single-walled carbon nanotube (CNT) Field Effect Transistor (FET)-based biosensing platform for real-time and sensitive protein detections is proposed. Aligned nanotubes were synthesized on quartz substrate using catalyst contact stamping, surface-guided morphological growth and chemical vapor deposition gas-guided growth methods. Real-time detection of prostate-specific antigen (PSA) using as-prepared FET biosensors was demonstrated. The kinetic measurements of the biosensor revealed that the drain current (I_d) decreased exponentially as the concentration of PSA increased, indicating that the proposed FET sensor is capable of quantitative protein detection within a detection window of up to 1 µM. The limit of detection (LOD) achieved by the proposed platform was demonstrated to be 84 pM, which is lower than the clinically relevant level (133 pM) of PSA in blood. Additionally, the reported aligned CNT biosensor is a uniform sensing platform that could be extended to real-time detections of various biomarkers.