In the present research, silver/carbon dot nanoparticles (Ag/CDs) were used for fluorescence determination of tetracycline (TC). For this purpose, extract of Malva with the scientific name of Malva Sylvestris from Malvaceae family with different medicinal properties and high nutritional value was used as the precursor for CDs synthesis and the reducing agent of silver ions through the hydrothermal method. The effect of synthesis parameters including AgNO3 and β-cyclodextrin concentrations, amount of extract, temperature, pH, and time were investigated on the preparation of Ag/CDs. The X-ray diffraction and energy-dispersive X-ray spectroscopy (EDS) confirmed the synthesis of Ag/CDs, and transmission electron microscopy (TEM) showed the construction of nanoparticles with an average size of 25 nm. The intensity of localized surface plasmon resonance (LSPR) absorption peak of silver nanoparticles was increased with addition of TC. In addition, with increasing the concentration of analyte, the fluorescence intensity of the Ag/CDs was enhanced due to metal enhanced fluorescence (MEF). By plotting the calibration curve using fluorescence data, the linear range of 0.025–3 ppm and the limit of detection of 0.6 μg L- 1 (1.2 nM) were obtained for the method. To evaluate the practical performance of the sensor, the TC determination was carried out in human blood plasma and satisfactory results were obtained.
