Detection of plasma miR-223 by a novel label-free graphene oxide/gold nanocomposite immunosensor in colorectal cancer patients: An electrochemical biosensor approach

Abstract

MicroRNAs (miRNAs) are one group of the pertinent molecular biomarkers in the early detection of cancers, especially colorectal cancer. A simple and label-free nanostructured electrochemical biosensor was fabricated to detect miR-223, a colorectal cancer miRNA, by a vertical arrangement of graphene oxide (GO) decorated with gold (Au) Nano-flower nanostructures (GO@Au-NS). The use of high surface-to-volume aspect ratio nanostructures with excellent electroactivity that contain thiolated DNA probes (Cap-223) could increase the accessibility, chance, and recognition performance of miR-223. The substrate characteristics are scanned by HRSEM, EDX, and electrochemical techniques. Furthermore, the successful immobilization of Cap-223 on GO@Au-NS and their hybridization with targeted miR-223 macro-molecules were investigated by electrochemical techniques (CV, EIS, and DPV). The electroactivity of the working electrode before and after GO@Au-NS fabrication showed a significant difference. A wide range of linear detection of miR-223 by a fabricated biosensor was from zM to nM, with a lower detection limit (LOD) of 0.012 aM. The selectivity of the nanostructured miR-223 biosensor was also investigated by studying the discrimination ability of mismatched miRNAs sequences, which resulted in high selectivity for the biosensor. In addition, its efficiency in the detection of miR-223 in a real sample (human serum) showed a remarkable ability of the biosensor to detect it with a low percent of relative standard deviation (RSD = 5.7%). The developed electrochemical biosensor exhibited great potential for miRNA-based early detection of colorectal cancer and had excellent sensitivity, and selectivity, making it helpful for use in translational medicine research and clinical applications.