Abstract

The unique micro-RNA signatures of different tumours distinguish cancer from normal tissue. MicroRNA-155 (miR-155) is one of the biomarkers approved for breast cancer diagnosis. Due to this compound's very low concentration level in the early stages of cancer in the human body, it is challenging to quantify this miRNA in serum/plasma using conventional methods. To accurately and specifically identify this biomarker, an electrochemical nanobiosensor is proposed in the present work that is constructed based on microRNA complementary strand hybridization, and the final signal was measured using hematoxylin as a label. To achieve these goals, a novel nanocomposite of carbon nanofiber, nickel-metal-organic frameworks (Ni-MOF@GO), Ag-doped graphene (GQD-Ag), and CdS quantum dots (CdSQDs) was used to immobilize single-stranded RNA probes. Various electrochemical methods, such as cyclic voltammetry, differential pulse voltammetry, and electrochemical impedance spectroscopy, were used to investigate the step by step of fabrication of the proposed nanobiosensor. The analytical results of applying the fabricated nanobiosensor for miR-155 determination showed a low detection limit of 0.1 fM with a dynamic range of 0.3 fM-500 pM under the optimal experimental conditions in PBS buffer. The nanobiosensor was also specific to the target miRNA sequence compared to one-, three-base mismatches, miR-21 (as the non-complementary target), and their combination. In addition, the nanobiosensor demonstrated a notable performance in evaluating real samples by not showing any noticeable interference. Hence, this platform is believed to be promising for future applications in diagnosing and screening breast cancer.