Study On The Synthesis Of Carbon Nanodots And Its Application

Xu, et al. first accidently found carbon nanodots in2004. In recent years, carbon nanodots has attractedwidespread research interest and gradually replaced semiconductor quantum dots in bioimaging andbiosensor fields due to its high fluorescence, good photostability, excellent biocompatibility, low-toxicityand environmentally friendly. What’s more, it has generated many applications in analytic chemistry,environment monitoring, solar and optoelectronic devices. The synthesise and application of carbonnanodots have been studied in the thesis, and the main researches are as follow:Microwave-assisted approach has been selected to prepare carbon nanodots by using succinic acid andcitric acid as the precursor materials and the prepared carbon nanodots were signified as SC-dots and CC-dots, respectively. The synthesized SC-dots are monodisperse with a narrow size distribution, and show ahigh fluorescence quantum yield. The UV-VIS and fluorescence spectra of these prepared carbon nanodotshave been investigated. The influence factors of the synthesis of the SC-dots and its XRD and FT-IR havealso been discussed. What’s more, the effects of acidity and High salt solution on the SC-dots have beenstudied. Cytotoxicity test showed that SC-dots and CC-dots were low-toxicity to the cell.The responses of carbon nanodots to the different metal ions have been studied, the quenchingmechanisms of the Cu2+, Hg2+to the SC-dots and the Fe3+, Hg2+to the CC-dots have been more detailedlyanalysised. Among all, The quenching of Cu2+and Hg2+to SC-dots showed as static and dynamicquenching, however, that of Fe3+and Hg2+to CC-dots showed as dynamic and static quenching,respectively.In alkaline conditions, Cu2+has the quenching effect on the fluorescence of SC-dots, ampicillin canrecovery the fluorescence of SC-dots due to its complex with Cu2+. Base on this phenomenon, afluorescence method for detecting ampicillin has been established. The UV-VIS and fluorescence spectra ofthe system have been discussed, the effects of pH, temperature and the dosage of reagent on the system aswell as have been optimized. Under the optimum conditions, the recovered fluorescence of the system andthe concentration of ampicillin is linear in the range0.4~6.0μg/mL with a correlation coefficient of0.999and detection limit of0.26μg/mL. This method can be applicated to detect ampicillin in the drugs andhumans urine, with a recoveries between99.7%and102.4%. In alkaline conditions, a more sensitive fluorescence method for the detection of o-phenylenediaminehas been builded using the phenomenon that o-phenylenediamine can cooperate with Fe3+to quench thefluorescence of carbon nanodots. The quenching mechanisms of the system have been more detailedlyanalysised, and the results indicated that the quenching of o-phenylenediamine and Fe3+to CC-dots wereboth dynamic quenching. The UV-VIS and fluorescence spectra have been scaned, and the effects of pH,temperature and the dosage of reagents on the system have also been investigated. Under the optimumconditions, the quenched fluorescence of carbon nanodots is proportional to the concentration of o-phenylenediamine over the8.0~220ng/mL, the detection limit is1.32ng/mL. The mothod can be used todetect the o-phenylenediamine in the well water and tap water, the recoveries all falled in the window of97.95%~108.9%.