Epithelial cancer biomarker EpCAM determination in peripheral blood samples using a microfluidic immunosensor based in silver nanoparticles as platform

Abstract

In the present work, we report a microfluidic immunosensor for epithelial cancer biomarker EpCAM (epithelial cell adhesion molecule) determination. It is based on the use of synthetized silver nanoparticles (AgNPs) covered by chitosan (Cts). AgNPs-Cts were covalently attached to the central channel (CC) of the microfluidic immunosensor. These nanoparticles were employed as platform for anti-EpCAM monoclonal antibodies immobilization for specifically recognize and capture EpCAM in peripheral blood samples. Afterwards, the amount of this trapped epithelial cancer biomarker was quantified by HRP-conjugated anti-EpCAM-antibody. HRP reacted with its enzymatic substrate in a redox process which resulted in the appearance of a current whose magnitude was directly proportional to the level of EpCAM in the peripheral blood sample. The structure and morphology of synthetized AgNPs-Cts were characterized by UV-visible spectroscopy, scanning electron microscopy (SEM), energy dispersive spectrometer (EDS) and X-ray diffraction (XRD). The calculated detection limits for microfluidic immunosensor and the commercial ELISA were 2.7 and 13.9 pg mL-1, respectively and the within- and between-assay coefficients of variation were below 6.37% for the proposed method. The microfluidic immunosensor is simple, sensitive, specific and reproducible. It has the potential for reliable point-of-care clinical diagnosis and prognosis of epithelial origin tumors in biological samples.