Immunomagnetic bead-based bioassay for the voltammetric analysis of the breast cancer biomarker HER2-ECD and tumour cells using quantum dots as detection labels

• Published in: Mikrochimica acta (1966) 2020-02, Vol.187 (3), p.184-184, Article 184
• Main Authors: Freitas, Maria, Nouws, Henri P. A., Keating, Elisa, Fernandes, Virginia Cruz, Delerue-Matos, Cristina
• Format: Article
• Language: English
• Subjects: Analytical Chemistry; Breast cancer; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Electric properties; Ethylenediaminetetraacetic acid; IX NyNA 2019. International Congress on Analytical Nanoscience and Nanotechnology; Microengineering; Nanochemistry; Nanotechnology; Original Paper
• ISSN: 0026-3672; 1436-5073
• DOI: 10.1007/s00604-020-4156-4

An electrochemical magnetic immunosensing strategy was developed for the determination of HER2-ECD, a breast cancer biomarker, and breast cancer cells in human serum. A sandwich assay was performed on carboxylic acid-functionalized magnetic beads (MBs) using a screen-printed carbon electrode (SPCE) as transducer surface. The affinity process was detected using electroactive labels; core/shell streptavidin-modified CdSe@ZnS Quantum Dots (QDs). Cd 2+ ions, released from the QDs, were determined by differential pulse anodic stripping voltammetry (DPASV). An assay time of 90 min, with an actual hands-on time of about 20 min, a linear range between 0.50–50 ng·mL −1 of HER2-ECD and a limit of detection of 0.29 ng·mL −1 were achieved. Analysis of live breast cancer cells was also performed using the optimized assay. Breast cancer cell lines SK-BR-3 (a HER2-positive cell line), MDA-MB-231 (a HER2-negative cell line) and MCF-7 (a cell line with low HER2 expression) were tested. The selectivity of the assay towards SK-BR-3 cells was confirmed. A concentration-dependent signal that was 12.5× higher than the signal obtained for the HER2-negative cells (MDA-MB-231) and a limit of detection of 2 cells·mL −1 was obtained. Graphical abstract Schematic representation of the electrochemical immunomagnetic assay for the determination of the breast cancer biomarker HER2-ECD and cancer cells using magnetic beads (MBs), a screen-printed carbon electrode (SPCE) as transducer surface and quantum dots (QD) as electroactive labels.