Integrated bio-affinity nano-platform into a microfluidic immunosensor based on monoclonal bispecific trifunctional antibodies for the electrochemical determination of epithelial cancer biomarker

KARINA BRAVO; FRANCISCO G. ORTEGA; GERMÁN A. MESSINA; MARÍA I. SANZ; MARTÍN A. FERNÁNDEZ BALDO; JULIO RABA

CLINICA CHIMICA ACTA

ELSEVIER SCIENCE BV

Lugar: Amsterdam; Año: 2017 vol. 464 p. 64 - 71

0009-8981

The epithelial cell adhesion molecule (EpCAM) is a biomarker that is highly overexpressed on the surface of epithelial carcinoma cells. In this study, silver nanoparticles covered with polyvinyl alcohol (AgNPs-PVA) were synthesized, characterized and used in a microfluidic immunosensor based on the use of anti-EpCAM recombinant antibodies as a trapping agent. The concentration of trapped EpCAM is then electrochemically 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 (at a working voltage as low as -0.10 V) is directly proportional to the concentration of EpCAM. Under optimized conditions, the detection limits for the microfluidic immunosensor and a commercial ELISA were 0.8 and 13.9 pg L-1, respectively. The within-assay and between-assay coefficients of variation are below 6.5% for the proposed method. The immunosensor was validated by analyzing patient samples, and a good correlation with a commercial ELISA was obtained. The good analytical performance is attributed to the efficient immobilization of the anti-EpCAM recombinant antibodies on the AgNPs-PVA, and its high specificity for EpCAM. This microfluidic immunosensor is intended for use in diagnosis and prognosis of epithelial cancer, to monitor the disease, and to assess therapeutic efficacy.