Analysis of breast cancer biomarker HER2 based on single stranded DNA aptamer and enzyme signal amplification

In this study, we described a new electrochemical immunosensor for detecting human epidermal growth factor receptor 2 (HER2) extra-cellular domain, as a breast cancer biomarker, in human serum samples. The im-munosensor uses anti-HER2 combined single walled carbon nanotubes (SWNT) to label the glassy carbon electrode (GCE) to enhance the electrochemical signal and present rich antibody domains. The biotin-labeled HER2-specific aptamers were used to recognize target HER2. Then, the streptavidin labeled alkaline phosphatase (AP) as detection probes combined the aptamers and generated electrochemical signals. AP has an excellent catalytic activity to substrate alpha-NP and significantly amplifies the detection signal for target HER2. Using the optimized experimental conditions, the immunosensor could response down to 0.23 pg mL-1 HER2 with a linear range from 1.0 pg mL-1 to 100 ng mL-1, and showed acceptable accuracy and reproducibility. The designed sensor was used to detect other biomolecules, and found no apparent electrochemical signal, indicating its high specificity. In addition, when the biosensor was used to analyze human serum samples, it also showed sufficient recovery rate and good precision. All the results above indicate that the developed biosensor can provide an excellent potential analysis platform in breast cancer diagnostics.