A Label-free Electrochemical Immunosensor for Highly Sensitive Detection of TNF α, Based on Star Polymer-modified disposable ITO Electrode

Background: Biomarkers are very important disease-related biomolecules which should be analyzed sensitive and selective in related physiological fluids or tissues. Tumor necrosis factor-alpha is a type of cytokine which plays vitlly important roles in different methabolic pathways such as cell death, survival, differentiation, proliferation and migration, and infectious and inflammatory diseases including rheumatoid arthritis, diabetes. Objective: In this study, it was aimed to develop a reliable tool based on star-shaped poly(glycidyl methacrylate) polymer coated disposable indium tin oxide electrode for determination of Tumor necrosis factor-alpha, an important disease biomarker. Methods: Star shaped polymer was used as an interface material for anti- Tumor necrosis factor alpha antibodies immobilization. The antibodies were immobilized covalently onto polymer coated indium tin oxide electrode. Electrochemical impedance spectroscopy and cyclic voltammetry techniques were used for all electrochemical measurements. Results: The suggested immunosensor exhibited a linear range between 0.02 and 4 pg/mL Tumor necrosis factor-alpha, and the detection limit was found as 6 fg/mL. Scanning electron microscopy and atomic force microscopy were used for electrode surface characterization. In addition, the suggested immunosensor was used for Tumor necrosis factor-alpha sensing in human serum samples. The results displayed recoveries between 97.07 and 100.19%. Moreover, this immunosensor had a simple fabrication procedure and a long storage-stability. Conclusion: A new biosensor based on a Star shaped polymer for the ultra sensitive determination of a biomarker Tumor necrosis factor-alpha was developed. The biosensor presented excellent repeatability and reproducubility, and also wide calibration range for Tumor necrosis factor-alpha.