Introduction: Low levels and high levels of ceruloplasmin (Cp) in serum cause several diseases such as Wilson's disease [1, 2], so its accurate determination in human fluids is much essential. To date, numerous DNA or RNA aptamers have been identified for various targets with high affinity that have been applied in various fields, such as therapeutics, diagnostics and biosensors [3, 4]. Aptamer-based biosensors have exceptional adequate, compared to the natural receptors, such as enzymes and antibodies. The intrinsic properties of aptamers, such as high flexibility of structure, and convenience in the design of their structure, enable to develop the various novel aptasensors. Experimentals: The proposed nanoaptasensor was based on a glassy carbon electrode modified with diazonium-functional multiwall carbon nanotubes. The aptamer was linked onto the electrode surface, via electrochemical approach, followed by chemical immobilization of aminated-aptamer. Each fabrication steps was accompanied by changes to the electrochemical parameters. The binding of Cp to aptamer was monitored using CV, DPV, and EIS. While detecting Cp with the aptamer-based biosensor, EIS and DPV of [Fe(CN)6] 3-/4- was used to quantify the response of the aptamer–Cp interaction. Results and Discussion: The different stages of the nanoaptasensor preparation were investigated by recording CV, DPV and EIS of a modified electrode in the presence of the reversible [Fe(CN)6] 4-/3- redox system. At the next step, the experimental parameters such as aptamer concentration, incubation time and pH in the solution was optimized. 2.0 µmol L-1 aptamer solution, pH of 7.4, and 20 min for incubation time were selected as optimized values for Cp sensing. Under the optimal condition, the proposed nanoaptasensor was employed for the determination of Cp using DPV and EIS. The calibration curve for Cp concentration was linear at 0.02 to 80.0 ng mL -1 with detection limit (signal-to-noise ratio of 3) of 1.7 pg mL -1 .
