Electrochemical immunoassay on expression of integrin β1 on tumor cells and drug-resistant tumor cells

An electrochemical indirect competitive immunoassay protocol as a promising cytosensing strategy was developed to detect integrin beta 1 expression on human breast cancer MCF-7 cells and adriamycin-resistant human breast cancer MCF-7 (MCF-7/ADR) cells and quantify the cell number. Integrin alpha 5 beta 1 was adsorbed on the gold-nanoparticle modified glassy carbon electrode to bind integrin beta 1 monoclonal antibody (anti-CD29 mAb). A sandwich structure was then formed using nanocomposites which consisted of horseradish peroxidase (HRP) labeled anti-antibody and gold nanoparticles. HRP bound on the electrode surface could cause an amperometric response of the hydroquinone-H2O2 system. The assembly of the sandwich structure was inhibited by tumor cells to give decreased enzyme-catalytic signals due to the capture of anti-CD29 mAb by integrin beta 1 on cell membranes. Under optimal conditions the relative current change (S) was proportional to the cell concentration from 1.6 x 10(3) to 2.0 x 10(6) cells mL(-1) with a detection limit of 700 cells mL(-1). Integrin beta 1 expression in MCF-7/ADR cells was found to be significantly higher than that in MCF-7 cells, indicating the increased adhesion ability of MCF-7/ADR cells. (C) 2012 Elsevier B.V. All rights reserved.