Alkaline phosphatase labeled antibody-based electrochemical biosensor for sensitive HE4 tumor marker detection

• We developed a magnetic bead-based immunosensor for the detection of ovarian cancer biomarker HE4 with a low limit of detection.
• Alternative enzyme alkaline phosphatase converts a number of substrates to electroactive compounds advantageous for sensitive electrochemical monitoring.
• Selective system for the analysis of complex sample without pre-purification steps

Quantitative determination of the serum level of human epididymis protein 4 (HE4), a tumor marker for ovarian carcinoma, has come to the fore of interest mainly due to the possibility for its detection in early stages of the disease when the sensing of other biomarkers is limited. We present a simple ELISA based approach for rapid HE4 detection including its immunomagnetic capturing accompanied by sensitive electrochemical detection of the electroactive product formed after enzymatic conversion of the substrate by alkaline phosphatase used as a label of anti-HE4 IgG. The proposed immunosensor offers stability in time and due to excellent limit of detection at 6.8 fM HE4, and limit of quantification of 23 fM meets the requirements for the early detection of this biomarker.