Anti-EpCAM modified LC-SPDP monolayer on gold microelectrode based electrochemical biosensor for MCF-7 cells detection

A succinimidyl 6-(3-[2-pyridyldithio]-propionamido) hexanoate (LC-SPDP) self-assembled monolayer (SAM) prepared onto a 500 pm (diameter) gold microelectrode (Au) surface has been utilized for covalent immobilization of anti-EpCAM antibody. Amino group on anti-EpCAM antibody was covalently bound with succinimidyl group on SAM via amide bond and unreacted active groups of LC-SPDP were blocked using 1% ethanol amine (EA). These anti-EpCAM/LC-SPDP/Au electrodes were characterized using cyclic voltammetric (CV) and fluorescence techniques, respectively. The anti-EpCAM/LC-SPDP/Au electrodes were exposed to solutions with different MCF-7 cell concentrations and CV technique was used to determine the cell concentration. Further, CV studies on blank 500 and 50 mu m (diameter) gold microelectrodes were used to identify cell via molecular profiling using ferrocene amidopentyl carboxylic acid based redox tagging and magnetic beads based enhancement. CV results confirm that the anti-EpCAM/LC-SPDP/Au based biosensor could detect MCF-7 cells in the range of 1 x 10(5)-1 x 10(8) with correlation coefficient of 0.999 and detection limit of 1 x 10(5) cells ml(-1) i.e. 100 cells in solution used for incubation (1 mu l). Molecular profiling studies suggest that smaller size microelectrode (50 mu m; diameter) with magnetic beads based enhancement can be employed to identify cell type. This work establishes the feasibility of using microelectrode based platform for breast cancer specific MCF-7 cell concentration estimation and their molecular profiling. (C) 2012 Elsevier B.V. All rights reserved.