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Quantitative detection of drug residues in animal food stuffs is very important. Excessive use of veterinarian veterinarians, like antibiotics are a serious threat to consumers, due to the residence of livestock products such as meat, milk, eggs. Rapid detection of antibiotics is essential by using an efficient, fast, affordable, and specific tool for risk reduction and food safety control. In the present study, an aptasensor based on pencil graphite electrode modified with nanomaterial including grapheme and gold, for rapid detection of tetracycline antibiotic was developed in milk samples. Cycle voltammetry and differential pulse voltammetry (DPV) techniques were used for response evaluation of aptasensor. In order to modification the graphite pencil electrode, the scanrate (40 mV/s) and the number of cycles (10) and immobilization time of graphene (90 min) were optimized. Under optimum conditions, using differential pulse voltammetry technique was found to increase linearly in the range of 1 × 10^-12 to 1 × 10^-5 M, with increasing concentration (R² = 0.985). The detection limit of the aptasensor was found to be 1.4× 10^-13 M. A review of functional characteristics including repeatability, reproducibility, satability, and selectivity suggests acceptable performance for aptasensor. Overall, the fabricated aptasensor has efficiency required to detect tetracycline in milk samples.

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Determination of antibiotic residues in food including honey is very important. To data, various methods have been developed to determination of antibiotics in honey and other animal products. In recent years, the fabrication of electrochemical biosensors in combination with nanomaterial has attracted much attention. In the present study, an impedometric biosensor based on nanomaterial including reduced oxide grapheme (RGO) and gold nanoparticles (GNP) was developed for antibiotic detection of tetracycline in honey samples. Cyclic voltammetry and electrochemical impedance spectroscopy techniques were used to evaluate the working electrode surface. Peak current values in different modes were 0.034, 0.048, 0.09, 0.020 and 0.015 μA for unmodified electrode, RGO, GNP, aptamer and antibiotic, respectively. Biosensor characteristics including reproducibility, reproducibility, stability, and selectivity were evaluated using resistance charge transfer data, the results showed that they were acceptable. In order to calculate recovery percentage, concentrations of 1×10^-9 and 1×10^-11 M were prepared from tetracycline and injected into honey samples. The results showed that the proposed biosensor provides 94.1% to 104.4% recovery rate for tetracycline in honey samples.