Development of immunoFET biosensor for detection of 3-nitrotyrosine

Abstract

3-Nitrotyrosine (3-NT) is one of the important biomarkers for the detection of excess of oxidative and nitrosative stress in the body, and derived from peroxynitrite-induced nitration of free and protein-bound at tyrosine residues. It was increased with oxidative/nitrosative stress-induced apoptosis in various tumor cells and many human diseases. Therefore, the analytical methods to detect 3-NT levels in biological samples are important for in vitro study of the apoptotic mechanism of the compounds and for the diagnosis of 3 NT-related diseases. In this study, an accurate, sensitive, and specific assay was developed for 3-NT based on the immunoFET biosensors and the effects of protein-A for orientated immobilization of antibody were investigated on the sensitivity of this biosensors. The comparison of sensor performance among two immobilization methods revealed that the assay sensitivity was appreciably improved and better with antibody attached covalently to the sensor surface than the immobilization method using protein-A. In addition, with this covalent immobilization technique, the output voltage shifts increased linearly (R2 = 0.9923) across the 3-NT concentrations range from 10 to 1000 ng/mL and the limit of quantification of 10 ng/mL and the limit of detection was 0.15 ng/mL. Thus, the developed immunoFET sensors would be applicable for the detection of 3-NT in the biological samples.