A highly sensitive and reliable detection of CA15-3 in patient plasma with electrochemical biosensor labeled with magnetic beads.

Abstract An early on-time detection of breast cancer can effectively affect the outcome of the treatment. Here, we developed an ultrasensitive, simple and reliable immunosensor to detect the lowest alteration of CA 15-3, the standard biomarker of breast cancer patients. The proposed immunosensor was achieved by modification of gold electrode by streptavidin to immobilize the biotinylated anti-CA 15-3 monoclonal antibody (mAb). Bovine serum albumin was used to prevent nonspecific binding. To improve the sensitivity of modified immunosensor, the sandwich signal enhancer consisting of streptavidin-coated magnetic beads conjugated with biotinylated horseradish peroxidase (HRP) and anti-CA 15-3 biotinylated mAb was applied. The electrochemical measurements were obtained in the presence of hydroquinone as a redox agent and H 2 O 2 as the activating agent of HRP. Under optimized condition and using square wave voltammetry, the lower limit of quantification was obtained as 15 × 10−6 U/mL and the linear CA 15-3 concentration range was 50–15 × 10−6 U/mL. While showing significant stability, the immunosensor displayed an excellent sensitivity and specificity for the detection of CA 15-3 even in the human serum as compared to the enzyme-linked immunosorbent assay (ELISA) as a gold standard method. Based on our findings, the engineered immunosensor is proposed as a robust diagnostic tool for the clinical determination of CA 15-3 and other cancer biomarkers. Highlights • An ultrasensitive and reliable immunosensor was developed for the detection of CA 15-3. • An enzymatic sandwich approach was applied to enhance the signals of the biosensor. • A significant lower limit of quantification was achieved. • An excellent performance of proposed immunosensor was observed compared to ELISA as the reference method. [ABSTRACT FROM AUTHOR]