In this paper, we report on fabrication of a label free, highly sensitive and selective electrochemical cortisol immunosensors using one dimensional (1D) ZnO nanorods (ZnO-NRs) and two dimensional nanoflakes (ZnO-NFs) as immobilizing matrix. The synthesized ZnO nanostructures (NSs) were characterized using scanning electron microscopy (SEM), selective area diffraction (SAED) and photoluminescence spectra (PL) which showed that both ZnO-NRs and ZnO-NFs are single crystalline and oriented in [0001] direction. Anti-cortisol antibody (Anti-C_ab) are used as primary capture antibodies to detect cortisol using electrochemical impedance spectroscopy (EIS). The charge transfer resistance increases linearly with increase in cortisol concentration and exhibits a sensitivity of 3.078 KΩ. M^-1 for ZnO-NRs and 540 Ω. M ^-1 for ZnO-NFs. The developed ZnO-NSs based immunosensor is capable of detecting cortisol at 1 pM. The observed sensing parameters are in physiological range. The developed sensors can be integrated with microfluidic system and miniaturized potentiostat to detect cortisol at point-of-care.

Date Published: 22 May 2014
PDF: 8 pages
Proc. SPIE 9107, Smart Biomedical and Physiological Sensor Technology XI, 91070U (22 May 2014); doi: 10.1117/12.2051156

Published in SPIE Proceedings Vol. 9107:
Smart Biomedical and Physiological Sensor Technology XI
Brian M. Cullum; Eric S. McLamore, Editor(s)