Date Published: April 4, 2017
Publisher: Public Library of Science
Author(s): Rebeca M. Torrente-Rodríguez, Víctor Ruiz-Valdepeñas Montiel, Susana Campuzano, María Pedrero, Meryem Farchado, Eva Vargas, F. Javier Manuel de Villena, María Garranzo-Asensio, Rodrigo Barderas, José M. Pingarrón, Reza Khodarahmi.
The first electrochemical immunosensor for the determination of fibroblast growth factor receptor 4 (FGFR4) biomarker is reported in this work. The biosensor involves a sandwich configuration with covalent immobilization of a specific capture antibody onto activated carboxylic-modified magnetic microcarriers (HOOC-MBs) and amperometric detection at disposable carbon screen-printed electrodes (SPCEs). The biosensor exhibits a great analytical performance regarding selectivity for the target protein and a low LOD of 48.2 pg mL-1. The electrochemical platform was successfully applied for the determination of FGFR4 in different cancer cell lysates without any apparent matrix effect after a simple sample dilution and using only 2.5 μg of the raw lysate. Comparison of the results with those provided by a commercial ELISA kit shows competitive advantages by using the developed immunosensor in terms of simplicity, analysis time, and portability and cost-affordability of the required instrumentation for the accurate determination of FGFR4 in cell lysates.
Nowadays cancer is one of the main causes of death worldwide . In fact, cancer mortality is becoming close to that of heart attacks . As a consequence, there is a high interest on the development of efficient strategies to diagnose the disease and fight against it. Early detection of neoplastic tumors is important due to the difficulty of combating cancer in advanced stages. Moreover, together with reliable cancer diagnosis, discovering new anticancer drugs and treatments is not less important.
The fundamentals and the electrochemical immunosensor developed for the determination of FGFR4 are displayed in Fig 1. Briefly, magnetic immunocarriers were employed for the selective capture of the target protein and to implement a sandwich format using a biotinylated detector antibody coupled to an enzymatic polymer (Strep-HRP). The reactions involved in the amperometric quantification of the FGFR4 protein at SPCEs using the HQ/H2O2 redox system are also shown in Fig 1.
The proposed methodology was applied to the determination of FGFR4 in raw lysates from 8 different cancer cells expressing variable amounts of the target receptor. Cancer cells from breast (MCF7, MDA-MB-436 and SKBR3), colon (KM12C, KM12SM, SW480 and SW620) and pancreas (BxPC3) were selected for the study. The complexity and the small amount of target protein contained in these samples required a high sensitivity and selectivity in the employed methodology, features demonstrated by the developed sensor, to provide reliable determinations.
This work describes the first biosensor developed so far for the determination of FGFR4 biomarker. The relatively simple design involving a sandwich format, magnetic immunocarriers assembled onto disposable platforms and amperometric transduction using the HRP/H2O2/HQ system, allows a highly sensitive (LOD of 48.2 pg mL-1) and selective determination of the target protein receptor in just 15 min using a single step protocol. The applicability of this approach has been demonstrated through the accurate determination of the endogenous content of FGFR4 in 8 different cancer cell lysates. The obtained results are in good agreement with those provided by a commercial ELISA methodology but using a simpler methodology and an 18 times lower analysis time (15 vs 280 min) once the cells lysates have been prepared. Therefore, the great analytical performance exhibited by this amperometric platform of simple and rapid operation, disposable format and the possibility to use pocket-size electrochemical transducers, can be claimed as important advantages for potential integration into portable and user-friendly point-of-care (POC) devices to perform high throughput routine determinations.