Preparation Of Carbon Nanodots And Their Applications In The Detection Of Environmental Pollutants And Drugs

Carbon nanodots（CNDs）,a new type of environmental-friendly carbon nanomaterials,because of their excellent luminescent properties,good biocompatibility,water-solubility and low toxicity,it has a wide range of applications involving photoelectric catalysis,environmental monitoring,drug analysis and other fields.In this thesis,two different carbon nanodots were prepared by simple hydrothermal method and their morphology,structure and optical properties were studied in detail by a series of characterization methods.Finally,it has utilized for multi-detection in drug and environmental pollutant detection.Chapter 1:Briefly describes the structure and composition,preparation methods and luminescence mechanism of carbon nanodots,and introduce the application research progress in cellular biological imaging,environmental monitoring and drug analysis.Chapter 2:Using green and environmental friendly biomass corn cob as carbon source,combined with direct carbonization method and one-step hydrothermal method,fluorescent biomass carbon nanodots were prepared.The results reveal that the average particle size of the prepared carbon dots is2.05 nm,the BCNDs in double-distilled waters emitted blue fluorescence and the optimal excitation wavelength and emission wavelength respectively locate at 357 and 437 nm.Based on the internal filtration effect,the fluorescence of BCNDS can be effectively quenched by Mn（Ⅶ）while ascorbic acid（AA）is reductive,it can reduce Mn（Ⅶ）to Mn（IV）/Mn（II）/Mn（0）,thus,the effect of IFE on the fluorescence of BCNDs is eliminated,and the fluorescence of BCNDs can be recovered.Therefore,a sensitive and selective on-off-on sensor platform for Mn（Ⅶ）and AA detection was constructed and successfully used in the actual sample detection.The recoveries of Mn（Ⅶ）were 97.40～103.77%,and the relative standard deviations were 1.98～5.76（n=3）.Chapter 3:Based on the BCNDs prepared in Chapter 2,its application in drug detection was further studied.After the addition of riboflavin（VB₂）into BCNDs,the fluorescence of the mixed system at 535 nm was enhanced while that at 435 nm was decreased;When DOX was added to BCNDs,the fluorescence of the mixed system at 553 nm was enhanced while that at 435nm was decreased.The results show that there is a fluorescence resonance energy transfer between BCNDs and VB₂/DOX,in which BCNDs are the energy donor and VB₂/DOX are the energy receptor.The liner range of VB₂was 0.27 to 7.21μM,and the detection limit was 4.43 nM.The detection range of DOX were 0.50 to 15.04μM and 20.36 to 70.15μM,respectively.The detection limit were 47.03 and 122.59,respectively.Finally,BCNDs were successfully used to detect VB₂and DOX in cells and actual samples.Chapter 4:Ru-doped orange-red fluorescent carbon nanodots（Ru-CNDS）were prepared by one-step hydrothermal method,using 1,10-phenanthroline,urea and ruthenium chloride as precursors.The results show that the fluorescence of Ru-CNDs at 600 nm could be effectively quenched by S₂O₈2-.Therefore,a lable-free,selective and high sensitive method for the determination of S₂O₈2-was established,the linear range and detection limits were 1.12-346.59μM and 250 nM,respectively.The fluorescent probe has good reproducibility for the specific recognition of S₂O₈2-and used for the actual sample detection.The recoveries were 95.65%～103.70%,and the relative standard deviations（RSDs）were 2.73%～9.76.