Highly sensitive and cost-effective ITO-based immunosensor system modified by 11-CUTMS: Analysis of SOX2 protein in real human serum.

In this study it is aimed to construct an immunosensor system for detection of Sex-determining region Y-box 2 (SOX2) antigen by using Indium tin oxide- polyethylene terephthalate (ITO-PET) as working electrode. Firstly, ITO-PET electrode surfaces were hydroxylated by using NH 4 OH/H 2 O 2 /H 2 O and were incubated with 11-cyanoundecyltrimethoxysilane (11-CUTMS), respectively. After silanization process, anti- SOX2 was immobilized on modified ITO-PET electrodes. All immobilization processes were examined with Electrochemical impedance spectroscopy (EIS) and Cyclic voltammetry (CV). The basic parameters such as 11-CUTMS and anti-SOX2 concentrations, anti-SOX2 and SOX2 incubation period were optimized. The immunosensor prepared under optimal conditions gave a response for a wide concentration range of SOX2 protein (0.02 pg mL−1–2 pg mL−1) and the limit of detection was determined as low as 0.013 pg mL−1. And also, the immunosensor had good repeatability, reproducibility, reusability and long shelf life. Scanning Electron Microscope (SEM) method was utilized to observe the morphologies of the electrode surfaces belonging to all steps. Lastly, seven different real human serum were analyzed with the constructed immunosensor and Enzyme-Linked ImmunoSorbent Assay (ELISA). The results found with these methods were analogised with each other. Unlabelled Image • The biosensor was designed by using disposable and very low-cost ITO-PET working electrode. • The new biosensor showed high analytical performance with a linear range 0.02 pg mL-1 -2 pg mL-1. • 11-cyanoundecyltrimethoxysilane, a novel silanization agent, was used to modify ITO-PET electrode surface. • The proposed biosensor was applied to the real human serum and compared with the results obtained from ELISA test. • Kruskal Wallis test was used to interpret the analysis results obtained with the biosensor and ELISA test for human serum. [ABSTRACT FROM AUTHOR]