Fully disposable microfluidic electrochemical device for detection of estrogen receptor alpha breast cancer biomarker

A novel fully disposable microfluidic electrochemical array device (mu FED) was developed and successfully applied for detection of the biomarker estrogen receptor alpha (ERa). The FED was constructed using low-cost materials and an inexpensive home cutter printer enabled the manufacture of dozens of mu FEDs in less than 2 h, at a cost of less than US$ 0.20 in material per device. The FED incorporates counter and reference electrodes and eight carbon-based working electrodes, which were modified with DNA sequences known as estrogen response elements (DNA-ERE), where ERa binds specifically. Paramagnetic particles heavily decorated with anti-ER alpha antibody and horseradish peroxidase (MP-Ab-HRP) were used to efficiently capture ERa from the sample solution. The ER alpha-MP-Ab-HRP bioconjugate formed was injected into the FED and incubated with the DNA-ERE-modified electrodes, followed by amperometric detection with application of -0.2 V vs. Ag vertical bar AgCl while a mixture of H2O2 and hydroquinone was injected into the microfluidic device. An ultralow limit of detection of 10.0 fg mL(-1) was obtained with the proposed method. The performance of the assay, in terms of sensitivity and reproducibility, was studied using undiluted calf serum, and excellent recoveries in the range of 94.7-108% were achieved for the detection of ERa in MCF-7 cell lysate. The FED system can be easily constructed and applied for multiplex biomarker detection, making the device an excellent cost-effective alternative for cancer diagnosis, especially in developing countries.