Immuno-probed graphene nanoplatelets on electrolyte-gated field-effect transistor for stable cortisol quantification in serum

• Published in: Journal of the Taiwan Institute of Chemical Engineers 2020-12, Vol.117, p.10-18
• Main Authors: Nur Nasyifa, Mohd Maidin, Ruslinda, A. Rahim, Abdul Halim, Nur Hamidah, Zainol Abidin, Azrul Syafiq, Mohd Faudzi, Fatin Nabilah, Ahmad, Nurul Atiqah, Lockman, Zainovia, Rezek, Bohuslav, Kromka, Alexander, Gopinath, Subash C.B.
• Format: Article
• Language: English
• Subjects: Cortisol; Field-effect transistor; Graphene nanoplatelets; Human serum; Immunosensor
• ISSN: 1876-1070; 1876-1089
• DOI: 10.1016/j.jtice.2020.12.008

•Integration of graphene nanoplatelets and field effect transistor (FET) has led to a sensitive biosensing platform.•Graphene nanoplatelets-EGFET immunosensor are able to detect cortisol biomarker in the 1.00 pg/mL to 10.00 ng/mL linear range with sensitivity of 72.30 µA.(g/mL)−1 and LOD of 0.85 pg/mL.•Specificity test using progesterone, cortisone and corticosterone was demonstrated.•The graphene nanoplatelets-EGFETs immunosensor is highly specific towards cortisol in complex human biological matrix. Physiological and emotional stress affects the regulation of cortisol secretion, a routine process in circadian rhythm. Regular monitoring of cortisol level as a biomarker in the blood stream becomes vital to determine cortisol-related diseases. This study reports immuno-probed graphene nanoplatelets on electrolyte-gated field-effect transistor (EGFET) biosensor for cortisol determination in human serum. Solution-processed graphene nanoplatelets were evidenced on the surface by Raman spectroscopy analysis and utilized as the transducing element on the field-effect transistor. Further, confirmed the binding events of the antibody on graphene nanoplatelets using X-Ray Photoelectron Spectroscopy and characterized the electrostatic gating effect of cortisol and intermediate functionalization on graphene nanoplatelets-EGFET. The biosensor exhibited good sensitivity of 72.30 µA.(g/mL)−1 in a linear range between 1.00 pg/mL to 10.00 ng/mL, with a limit of detection (LOD) of 0.85 pg/mL. Confirmation with binding events on the biosensor was done using the relevant molecules, progesterone, cortisone, and corticosterone, and found to be selective towards cortisol. Cortisol was also successfully detected with interference by the human serum, suggesting the capability of graphene nanoplatelets-EGFET sensor for determining cortisol in a complex matrix.