A novel electrochemical biosensor for sensitive detection of non-small cell lung cancer ctDNA using NG-PEI-COFTAPB-TFPB as sensing platform and Fe-MOF for signal enhancement

Non-small cell lung cancer (NSCLC) is the most common type of lung cancer with poor survival, in part because that half of the cases are already in advanced stage when they are diagnosed. In response to this issue, the present work constructed a novel electrochemical biosensor for sensitive detection of circulating tumor DNA (ctDNA) related to NSCLC. Specifically, polyethyleneimine (PEI) and covalent organic framework (COFTAPB-TFPB) functionalized nitrogen-doped graphene (NG) nanocomposite (NG-PEI-COFTAPB-TFPB) was designed and employed as sensing platform for the first time. NG-PEI-COFTAPB-TFPB with porous structure and good conductivity showed a synergistic effect on promoting electron transfer, which could provide large specific surface area and active sites to increase the immobilization of capture probe (CP). In addition, gold nanoparticles (AuNPs) decorated Fe-based metal-organic framework (Fe-MOF) were labeled with signal probe (SP) to form tracer label, which would attach to the electrode surface by sandwich hybridization of target probe (TP) with CP and SP. Consequently, FeIII from Fe-MOF could react with K4[Fe(CN)6] to form electroactive prussian blue, generating a significantly amplified electrochemical detection signal. Under optimum conditions, the proposed DNA biosensor displayed a broad linear range for ctDNA determination from 100 fM to 100 nM with a detection limit of 7.65 fM. Moreover, the biosensor was successfully fabricated to assay ctDNA in human serum, indicating the potential for cancer diagnosis. More importantly, the high sensitivity and satisfactory stability of this biosensor make it a promising method to detect other biomolecules by changing the corresponding sequences of CP and SP.