Single-step label-free nanowell immunoassay accurately quantifies serum stress hormones within minutes

A non-faradaic label-free cortisol sensing platform is presented using a nanowell array design, in which the two probe electrodes are integrated within the nanowell structure. Rapid and low volume (<5 mu l) sensing was realized through functionalizing nanoscale volume wells with antibodies and monitoring the real-time binding events. A 28-well plate biochip was built on a glass substrate by sequential deposition, patterning, and etching steps to create a stack nanowell array sensor with an electrode gap of 40 nm. Sensor response for cortisol concentrations between 1 and 15 mu g/dl in buffer solution was recorded, and a limit of detection of 0.5 mu g/dl was achieved. Last, 65 human serum samples were collected to compare the response from human serum samples with results from the standard enzyme-linked immunosorbent assay (ELISA). These results confirm that nanowell array sensors could be a promising platform for point-of-care testing, where real-time, laboratory-quality diagnostic results are essential.

Automated summary

A non-faradaic label-free cortisol sensing platform was developed using a nanowell array design, allowing for rapid and low volume sensing. The sensor, built on a glass substrate, showed a good response to cortisol concentrations and compared well with results from standard ELISA. Nanowell array sensors have potential to be a promising platform for point-of-care testing.