Electrochemical detection of non-small cell lung cancer (NSCLC) mir-223 biomarker employing gold/MWCNT nanocomposite–based sandwich platform

Recently, microRNA-223 (miR-223) has emerged as a new prognostic and diagnostic biomarker for detecting non-small cell lung cancer (NSCLC); thus, sensitive and selective detection of miR-223 is important in the early phase of cancer management. Herein, a simple miR-223 biosensor is developed using a biotin-tagged double-stranded DNA-RNA hybrid structure sandwiched between a recognition probe and a bioconjugate as a signaling unit. The recognition probe (MWCNT/AuNPs/DNA-1//GCE) is fabricated by immobilizing thiol-modified capturer DNA (DNA-1) onto a predesigned multiwall carbon nanotubes/gold nanoparticle–modified glassy carbon electrode (MWCNT/AuNPs//GCE) via Au–S interaction. However, 6-(Ferrocenyl)hexanethiol (Fc-SH) coupled streptavidin/AuNPs bioconjugate (Sv/AuNPs/Fc-SH) can selectively bind to biotinylated dsDNA-RNA hybrid via biotin − streptavidin conjugation and generates electrooxidation signal directly under applied potential. The proposed sensor demonstrates linear dynamic response as a function of log concentration of miR-223 (log C miR-223 ) ranging from 1 pM to 10 nM with a relatively low detection limit of 0.73 pM (3σ/sensitivity, n = 3) and is capable of discriminating miR-223 from its homologous sequences, hence can be considered for the diagnosis of clinical samples. Graphical Abstract