Electrochemical immunosensing of Growth arrest‐specific 6 in human plasma and tumor cell secretomes

Growth arrest-specific 6 (GAS6) protein plays a key role in processes related to proliferation, inflammation, angiogenesis, and atherosclerotic plaque formation. In addition, it has been reported that plasma levels of GAS6 are related to cancer prognosis and other relevant pathologies, such as heart failure or sepsis. We report here the first electrochemical immunoplatform for the determination of GAS6, which has demonstrated to be competitive with other available methodologies in terms of cost, simplicity, and decentralized application. The developed immunoplatform involves a sandwich immunoassay using magnetic microparticles (MBs) and uses amperometric detection at disposable screen-printed carbon electrodes (SPCEs). The MBs were modified with an antibody specific to GAS6 for its selective capture, which is further recognized by a biotinylated secondary antibody subsequently labeled with a streptavidin-horseradish peroxidase (Strep-HRP) conjugate. The electrochemical detection was carried out using the hydroquinone (HQ)/H2O2 system. The developed bioplatform exhibits a great selectivity and low limit of detection (27 pg/mL) that allowed the determination of the GAS6 circulating level in plasma samples from patients suffering heart failure (HF) and diagnosed with pancreatic ductal adenocarcinoma (PDAC), as well as the determination of the target protein in raw secretomes of human colorectal cancer cell lines.
This work is part of the POSITION-II project fundedby the ECSEL Joint Undertaking under grant numberEcsel-783132-Position-II-2017-IA;www.position-2.eu,and PCI2018-093067 (Spanish Ministerio de Ciencia eInnovación) to M.P. The financial support of PID2019-103899RB-I00 (Spanish Ministerio de Ciencia e Inno-vación) Research Project to S.C., PI17CIII/00045 andPI20CIII/00019 grants from the AES-ISCIII program toR.B. and the TRANSNANOAVANSENS-CM Program fromthe Comunidad de Madrid (Grant S2018/NMT-4349) toS.C., RTI2018-095672-B-I00 (Spanish Ministerio de Cienciae Innovación) to P.G.F.; Fundació la Marató de TV3 project081010toM.B.; researchprojectPI20/00625,fromtheAES-ISCIII/FEDER program, to P.N, are gratefully acknowl-edged. A. Montero-Calle acknowledges the support of theFPU predoctoral contracts by the Spanish Ministerio deEducación, Cultura y Deporte. G.S-F. is recipient of a pre-doctoral contract (grant number 1193818N) supported byThe Flanders Research Foundation (FWO). C. Muñoz-SanMartín acknowledges a predoctoral contract from Complutense University of Madrid. R.M. Torrente-Rodríguezacknowledges a Talento-Contract from Comunidad deMadrid (2019-T2/IND-15965).