Development of highly sensitive electrochemical immunosensor based on single-walled carbon nanotube modified screen-printed carbon electrode

An electrochemical immunosensors have great potential for use in medical applications because of their high sensitivity and ease of measurement. However, the main challenge associated practical use of electrochemical immunosensors is an achievement of high sensitivity, reliable and reproducible fabrication on a low-cost platform. In this report, a sensitive electrochemical immunosensor has been developed for the detection of hCG, a pregnancy marker, that is based on a single-walled carbon nanotube (SWCNT) modified screen-printed carbon electrode. This electrochemical immunosensor is a sandwich-type immunoassay, where the gold-linked with the second antibody (Au-Mab-hCG) used as a label. The differential pulse voltammetry was employed to measure the signal current response obtained from dissolved Au-Mab-hCG. The signal amplification strategy-using gold nanoparticles as bio-tracker and SWCNT enhanced electron transfer nearly twice comparing with bare SPCE. The performance of the electrochemical immunosensor was also improved by the use of the coated materials in preventing non-specific binding. The developed electrochemical immunosensor shows the linear range of the hCG concentration from 10 pg/mL to 1000 pg/mL, the limit of detection of 5 pg/mL with the sample volume usage as low as 2 mu L.