Fluorescence Quenching Effect Of Interaction Between Carbon Quantum Dots And Drugs And Its Analytical Application

Carbon quantum dots(CQDs)are new type of fluorescent carbon probes,which are not only similar to the traditional semiconductor quantum dots which has the luminous characteristcs of small size and good light stability,but also with characteristcs of low cost,mild reaction conditions,easy measurement,good water-solubility and low bio-toxicity.By replacement of the traditional semiconductor quantum dots,such CQDs can be applied to biological imaging,bio-labelling,environment detecting,photoelectrocatalysis and drug detection & analysis,etc.At present,CQDs have become a hotspot in the identification and detection of ions,but seldom in drug analysis.In this thesis,several kinds of carbon quantum dots with high fluorescence quantum yield were synthesized by using simple synthesis method and low-priced carbon source.And such carbon quantum dots were used as fluorescent probes to study the application of fluorescent carbon quantum dots in drug analysis in order to realize the quantitative detection of drug,which will provides a certain experimental basis for the interaction between quantum dots and drug.The paper includes two major parts,one is literature review,and another is the research report including the following:1.Taking sugar as carbon source,one-step hydrothermal synthesis method was used to synthesize the luminescent carbon quantum dots of which luminescent properties were studied by fluorescence spectra,ultraviolet-visible absorption of spectra and infrared spectra,and also the fluorescence lifetime was determined and the interaction between doxycycline hyclate and such carbon quantum dots was studied.The experiments showed that in the p H=7.96 BR buffer solution,the fluorescence intensity of the carbon quantum dots was obviously quenched by doxycycline hyclate and a new method for determining doxycycline hyclate was put forward at the basis of using carbon quantum dots as probes.The method gave a linear response(r=0.9992)for doxycycline hyclate from 2.0 × 10-7 mol/L to 3.0 × 10-5 mol/L with a theoretical detection limit of 1.94×10-7 mol/L.And the method had been applied to determine doxycycline hyclate in samples,with recovery ranged from 97.2% to 99.5%.The quenching type between doxycycline hyclate and the carbon quantum dots was determined by measuring the temperature effect on the quenching constant and the change of the ultraviolet-visible absorption of spectra.2.In this work,taking sodium citrate and ammonium acetate as carbon source,one-step microwave synthesis method was used to synthesize new carbon quantum dots.The new carbon quantum dots exhibit excellent water-solubility,good photostability,and a high quantum yield(about 50.4%).Fluorescence spectra,ultraviolet-visible absorption of spectra and infrared spectra were used to study the luminescent properties of the carbon quantum dots,and the fluorescence lifetime was determined.The interaction between tetracycline hydrochloride and the carbon quantum dots was studied.The experiments showed that in the p H=7.24 BR buffer solution,the fluorescence intensity of the carbon quantum dots was obviously quenched by tetracycline hydrochloride.The method gave a linear response(r=0.9991)for tetracycline hydrochloride from 1.0 × 10-7 mol/L to 2.0 × 10-5 mol/L with a theoretical detection limit of 8.46×10-8 mol/L.The method was applied to determine tetracycline hydrochloride in the drugs with recovery ranged from 95.2% to 102.8%.The quenching type between tetracycline hydrochloride and the carbon quantum dots was determined as static by measuring the temperature effect on the quenching constant and the change of the ultraviolet-visible absorption of spectra.3.In the p H=8.0 Na2HPO4-Na H2PO4 buffer solution,the fluorescence intensity of the carbon quantum dots was quenched by oxytetracycline hydrochloride characterized at 442 nm and the fluorescence intensity of the carbon quantum dots quenched showed a linear relationship with the concentration of oxytetracycline hydrochloride,based on which the fluorescence spectrophotometry was established to determine oxytetracycline hydrochloride.Optimizing the experimental conditions,the quenching type between oxytetracycline hydrochloride and the carbon quantum dots was determined as dynamic by measuring the temperature effect on the quenching constant,the change of ultraviolet-visible absorption of spectra and the fluorescence lifetime.The method gave a linear response(r=0.9975)for oxytetracycline hydrochloride from 3.0 × 10-7mol/L to 2.0 × 10-5 mol/L with a theoretical detection limit of 1.53×10-7 mol/L.The method was applied to determine the tablet content of oxytetracycline hydrochloride with recovery ranged from 97.5% to 102.5%.4.In this work,taking triethanolamine as carbon source and nitrogen source,microwave synthesis method was used to synthesize the water-soluble carbon quantum dots(NCDs).The luminescence properties of the water-soluble carbon quantum dots were studied,and the fluorescence lifetime was determined.The experiments showed that in the p H=5.72 BR buffer solution,the fluorescence intensity of NCDs was obviously quenched by ornidazole,based on which a new method for the determination of ornidazole was put forward by using NCDs as fluorescent probes.The effects of various factors on the reaction system were investigated,such as the amount of buffer solution,the type of buffer solution,the amount of quantum dots,the reaction time,the reaction temperature and the surfactant.The method gave a linear response(r=0.9960)for ornidazole from 8.0 × 10-7 mol/L to 1.0 × 10-4 mol/L with a theoretical detection limit of 7.3×10-7 mol/L.The method was applied to determine ornidazole in samples with recovery ranged from 98.50% to 102.0%.At the same time,the quenching mechanism of the system was studied.And the quenching type between ornidazole and NCDs was determined as dynamic by measuring the temperature effect on the quenching constant and the change of the ultraviolet-visible absorption of spectrometry.