Electrochemical nano-genosensor for highly sensitive detection of miR-21 biomarker based on SWCNT-grafted dendritic Au nanostructure for early detection of prostate cancer

MicroRNAs (miRNAs) appear as a novel reliable candidate in biomarkers for early diagnosis of cancer. Due to their roles in various types of cancer, their potential as a diagnostic biomarker is getting more attention. Here, a novel electrochemical biosensor for detection of miR-21 was demonstrated, through combining the advantages of electrochemical methods and nanomaterials with the selectivity of oligonucleotides, based on thiolated receptor probe-functionalized dendritic gold nanostructures (den-Au) via the self-assembly monolayer (SAM) process which grafted on the single-wall carbon nanotubes (SWCNTs) platform on the surface of the fluorinedoped tin oxide (FTO) electrode. Cadmium ions (Cd2+) were used as signal units and also signal amplification substance which labeled before on miR-21 target. The oxidation signal of Cd2+ as a signal unit was measured by differential pulse voltammetry (DPV) technique that had a very wide linear relationship with the concentration of miR-21 target (0.01 fmol L-1 to 1 mu mol L-1) and low experimental detection limit of 0.01 fmol L-1. Furthermore, fabricated biosensor showed acceptable performance in human serum samples and also good selectivity indiscriminate between the complementary target and non-complementary one, so this nano-genosensor can clinically be used for prostate cancer diagnosis through the detection of miR-21 in human serum samples.