Mostafa Azimzadeha - Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran,Tehran, Iran.
Mahdi Rahaie - Department of Life Science Engineering, Faculty of New Sciences and Technologies, University of Tehran,Tehran, Iran.
Navid Nasirizadeh - Department of Textile and Polymer Engineering, Yazd Branch, Islamic Azad University, Yazd, Iran.
Hossein Naderi-Manesh - Department of Nanobiotechnology/Biophysics, Faculty of Biological Sciences, Tarbiat Modares University, Tehran, Iran.

Circulating miRNAs have been becoming as one of the most important biomarkers for cancer early detection (1). Biosensors are the attending class of miRNA quantification methods due totheir great specificity and selectivity. The electrochemical biosensors are the most attractive method, because of their inexpensive, fast and precise detection (2). Additionally, nanobiosensors are the biosensors which are using nanomaterials for signal amplifying andimproving the sensitivity of the detection system (3). Many of nanomaterials have been synthesized with different elements, shapes, structures, aspect-ratios and functionalization scheme, based on their goal application. In this research, graphene oxide and gold nanorodsapplied in an electrochemical nanobiosensor for miRNA quantification (4). The graphene oxide used for expanding the active area of electrode surface, and the gold nanorods attaching to the graphene oxide sheet to provide a media for attachment of thiolated single strand probes (SSprobe)(5-6). The probe was designed to specifically and selectively hybridize to the target miRNA. Additionally, Oracet blue used as an electroactive label which can intercalates withdouble strand oligonucleotide and the reduction signals of OB is measured by differential pulse voltammetry (DPV). The results showed that application of graphene oxide and gold nanorods are very effective in signal amplification and the current for nanobiosensor is much highercompared to the method that not used nanomaterials (Fig 1). In the optimization of experiments which is shown in the Fig 2, the maximum current for the nanobiosensor was achieved at the concentration of the graphene oxide and gold nanorods, 1.0 mg/mL and 100μg/mL, respectively. In conclusion, the application of nanomaterials, graphene oxide and gold nanorods, have extensively improved the electrochemical signals, succeeded the better sensitivity and lower detection limit

nanomaterial, Graphene oxide, Gold nanorods, Nanobiosensor