A Simple and Sensitive Assay for Protein Kinase a Using Single-walled Carbon Nanotube Field-Effect Transistor

Fabrication and Functionalisation of Nanocarbon-Based Field-Effect Transistor Biosensors

Nanocarbon-based field-effect transistor (NC-FET) biosensors are at the forefront of future diagnostic technology. By integrating biological molecules with electrically conducting carbon-based platforms, high sensitivity real-time multiplexed sensing is possible. Combined with their small footprint, portability, ease of use, and label-free sensing mechanisms, NC-FETs are prime candidates for the rapidly expanding areas of point-of-care testing, environmental monitoring and biosensing as a whole. In this review we provide an overview of the basic operational mechanisms behind NC-FETs, synthesis and fabrication of FET devices, and developments in functionalisation strategies for biosensing applications.

A chemodosimeter-modified carbon nanotube-field effect transistor: toward a highly selective and sensitive electrical sensing platform

We present a carbon nanotube-field effect transistor (CNT-FET) biosensor which first implements the chemodosimeter sensing principle in CNT nanoelectronics. We experimentally illustrate the specific molecular interplay that the cysteine-selective chemodosimeter immobilized on the CNT surface can specifically interact with cysteine, which leads to the chemical transformation of the chemodosimeter. Since the chemical transformation of the chemodosimeter can disrupt the charge distribution in the vicinity of the CNT surface, the carrier equilibrium in CNT might be altered, and manifested by the conductivity change of CNT-FET. The real-time conductance measurements show our biosensor is capable of label-free, rapid, highly selective and ultrasensitive detection of cysteine with a detection limit down to 0.45 fM. These results first verify the signaling principle competency of chemical transformation of the chemodosimeter in CNT electronic sensors. Combined with the advantages of the highly selective chemodosimeter and sensitive CNT-FET, the excellent performance of our sensor indicates its promising prospect as a valuable tool for developing highly sensitive and selective sensing platforms in practical application.

The utility of the chemodosimetric sensing principle was demonstrated for the first time in electronic biosensing with CNT-FET devices.

Rapid Detection of Protein Kinase on Capacitive Sensing Platforms

In this study, we developed a capacitive sensor for the one-step and label-free detection of protein kinase A (PKA) enzyme. Metal-insulator-semiconductor (MIS) and electrolyte-insulator-semiconductor (EIS) are a simple electronic transducer, which allows efficient detection of the target analyte. For this reason, we performed a comparative sensing of PKA on the MIS and EIS capacitive sensor. The PKA-specific aptamer was used for the one-step detection. For the immobilization of thiolated aptamer, the MIS sensor contained a thin gold layer, whereas the EIS sensor had a self-aligned monolayer of gold nanoparticles. The interaction of aptamer and PKA changed the charge and density of the sensor surface. The quantitative detection of PKA was performed by analyzing the capacitance-voltage curve after the aptamer-PKA interaction. The MIS and EIS sensor showed a detection limit of 5 U/mL and 1 U/mL, respectively, for the detection of PKA. This study suggests valuable sensing platforms for the rapid and sensitive biochemical diagnosis.