Aptamer based strategy for cytosensing and evaluation of HER-3 on the surface of MCF-7 cells by using the signal amplification of nucleic acid-functionalized nanocrystals.

The electrochemical detection of cell lines of MCF-7 (human breast cancer) has been reported, using magnetic beads for the separation tool and high-affinity DNA aptamers for signal recognition. The high specificity was obtained by using the magnetic beads and aptamers, and the good sensitivity was realized with the signal amplification of DNA capped CdS or PbS nanocrystals. The ASV (anodic stripping voltammetry) technology was employed for the detection of cadmic cation and lead ions, for electrochemical assay of the amount of the target cells and biomarkers on the membrane of target cells, respectively. This electrochemical method could respond to as low as 100 cells mL(-1) of cancer cells with a linear calibration range from 1.0×10(2) to 1.0×10(6) cells mL(-1), showing very high sensitivity. Moreover, the amounts of HER-3 which were overexpressed on MCF-7 cells were calculated correspond to be 3.56×10(4) anti-HER-3 antibody molecules. In addition, the assay was able to differentiate between different types of target and control cells based on the aptamers and magnetic beads used in the assay, indicating the wide applicability of the assay for early and accurate diagnose of cancers.