carbon quantum dots as a fluorescent sensing platform for amoxicillin detection

Abstract: quantum dots (qds) are semiconductor nanoparticles with unique optical and electrical properties that have been extensively studied and used for analytical purposes in the last two decades due to their strong fluorescence emission and tunable nanoparticle sizes [1]. however, many qds are toxic even at relatively low concentration. one of the most recently discovered qds are carbon dots (cds) or carbon quantum dots (cqds) [2]. due to ease of synthesis methods, low cost, low toxicity, strong fluorescence emission, environmental compatibility and abundant synthesis sources, applications of cqds has expanded in the fields of bioimaging, drug delivery and chemical sensors [3]. amoxicillin as an antibacterial drug, strengthens the immune system and is used to treat bacterial infections [4]. in this study, carbon quantum dots were synthesized using hydrothermal method and used for measuring amoxicillin based on fluorescence quenching technique. preliminary studies have shown that the intensity of cqds fluorescence (λex=350 nm and λem=440 nm) is related to the concentration of amoxicillin, in which increasing its concentration reduces the fluorescence intensity of cqds. based on these observations, the effect of various factors such as ph, temperature, time and ionic strength of the analytical solution on the fluorescence of cqds were studied and optimized. according to the experimental data, the linear dynamic range of 2.0-30.0 μm amoxicillin, the method detection limit of 2.0 μm amoxicillin and the relative standard deviation of 0.2 % in repeated measurements of 10 μm amoxicillin were obtained. the effect of many ionic species and different chemical compounds on the analytical signals (fluorescence intensity of cqds) were also investigated. the proposed method for measuring the amount of amoxicillin in pasteurized milk samples was also used and evaluated.