Aptamer-based label-free immunosensors using carbon nanotube field-effect transistors

In this paper, aptamer-based label-free immunosensors were fabricated for immunoglobulin E (IgE) detection using carbon nanotube field-effect transistors (CNTFETs). Aptamers are artificial oligonucleotides and thus are smaller than the Debye length. After aptamers were covalently immobilized on CNT channels, the electrical properties of the CNTFETs were monitored in real time, indicating that IgE in the range of 250 pM - 160 nM is effectively detected. From the measurement of the dependence of CNTFET electrical properties on IgE concentration, the dissociation constant between aptamer and IgE reactions is estimated to be 1.9 × 10^-9 M using the Langmuir adsorption isotherm, revealing that IgE and aptamers have good affinity. Therefore, aptamer-based CNTFETs are a promising candidate for the development of an integrated, high-throughput, multiplexed real-time biosensor for medical, forensic and environmental diagnostics.