Sensitive on-chip detection of cancer antigen 125 using a DNA aptamer/carbon nanotube network platform

Despite the major role of cancer antigen 125 (CA125) in cancer progression, its structural diversity makes antibody-based immunoassay of this protein difficult. Here we report the selection of an anti-CA125 ssDNA aptamer and its application to sensitive detection of CA125 when used together with a CA125-specific antibody immobilized on a three-dimensional network of carbon nanotubes (3DN-CNTs). With exceptional stability and easy modifications over antibodies, the selected ssDNA aptamer (rCAA-8) showed high binding affinity (166 nM) for recombinant CA125, which enabled CA125-specific imaging in ovarian cancer cells (OVCAR-3). Furthermore, when compared to other fluorescent assays based on graphene oxide or flat surface and traditional enzyme-linked immunosorbent assay, a chip-based assay using a 3DN-CNT surface and anti-CA125 antibody-aptamer pair resulted in higher sensitivity and broader dynamic range as a function of CA125 concentration, due to high target specificity and high surface loading density. Our on-chip aptamer-based assay will facilitate sensitive and specific monitoring of CA125 in the biological and clinical fields. (C) 2017 Elsevier B.V. All rights reserved.This work was supported by the National Research Foundation (NRF) grants funded by the Korean government (MSIP) (No. 2012M3A7B4035286 and 2016M3A9B4918833). This work also supported by the MSIT (Ministry of Science and ICT), Korea under the ITRC (Information Technology Research Center) support program (IITP-2017-1711055214) supervised by the IITP (Institute for Information & communications Technology Promotion). This work was also supported by Basic Science Research Program (No. 2012R1A6A1029029) through the NRF funded by the Ministry of Education. Funding was also provided by the grant (FA2386-15-1-4081) from the AFOSR/AOARD, USA