Development of screen-printed electrode based immunosensor for the detection of HER2 antigen in human serum samples

In this study, an immunosensor based on screen-printed electrode (SPE) has been developed for the detection of Human Epidermal Growth Factor Receptor-2 (HER2) antigen. The SPEs were fabricated and a sandwich enzyme linked immunosorbent assay (ELISA) format was followed for the construction of the immunosensor. The capture antibody (mouse anti-human ErbB2) was coated onto the electrode surface without any prior surface modification, followed by the addition of recombinant human HER2 antigen. Biotinylated goat anti-human ErbB2 was used as the detection antibody which was linked to streptavidin conjugated horseradish peroxidase (HRP). 3,3',5,5'-tetramethylbenzidine (TMB) was used as the substrate. The redox reaction was measured using cyclic voltammetry at scan rate of 50mV/s for the quantification of the antigen in solution. The biotin-avidin chemistry enabled the accurate detection of the antigen in nanogram levels. The amperometric signal obtained increased linearly with increase in the HER2 concentration and two-fold linear range was obtained between 5ng/ml-20ng/ml and 20-200ng/ml respectively. The limit of detection (LOD) and the limit of quantification (LOQ) of this immunosensor were found to be 4ng/ml and 5ng/ml respectively. The detection of HER2 in the serum samples of invasive and non-invasive breast cancer patients has been realized.