Novel sensitive immunosensor for the selective detection of Engrailed 2 urinary prostate cancer biomarker

Engrailed 2 (EN2) is a homeodomain-containing transcription factor expressed in prostate cancer (PCa) cell lines and is secreted into the urines. It is nowadays considered as a promising non-invasive biomarker for PCa early diagnosis. Herein, we report the design of an electrochemical immunosensor for EN2 detection. The biosensor fabrication involved a covalent immobilization of anti-EN2 antibodies onto a poly para amino benzoic acid (PABA) film electropolymerized on a gold electrode. Square wave voltammetry was investigated for EN2 detection in a phosphate buffer solution in a concentration range of 10-5 ng/mL to 1 mu g/mL. The limit of detection of the designed sensor was equal to 10-5 ng/mL and the sensitivity was of order of (29 +/- 2) mu L/ng. The dissociation constant Kd of the complex EN2/anti-EN2, estimated from a Hill model, was of order of (0.9 +/- 0.2) fM. Experimental results revealed that the immunosensor enabled selective detection of EN2 in a mixture of three proteins which can be found in men' urine: human serum albumin (HSA), prostate-specific antigen (PSA) and immunoglobulin G (IgG). Tests in artificial urine, with an ionic strength of 0.18 M, have been done and results were found comparable to those obtained in PBS (0.16 M).These encouraging results show a potentially promising future for the development of an electrochemical biosensor for robust and accurate urinary biomarkers detection.

Automated summary

This study reports the design of an electrochemical immunosensor for detecting prostate cancer. The immunosensor was able to selectively detect EN2 in urine and showed comparable results in artificial urine to those obtained in PBS. These findings suggest a potentially promising future for the development of robust and accurate urinary biomarker detection using electrochemical biosensors.