Preparation And Application Of Two Elemental Fluorescent Nanomaterials In Environmental And Biological Analysis

In recent years,the application of fluorescent nanomaterials in catalytic,analysis,biology and medicine has attracted much attention.Among them,metal-free elemental fluorescent nanomaterials have a good application prospect in the field of analysis and detection due to their low toxicity and good solubility and optical stability.By means of covalent or self-assembly method,this paper endowing the elemental fluorescent nanomaterials with certain specificity,thus constructing a variety of optical sensing systems based on fluorescent nanomaterials,and realizing sensitive detection of heavy metal ion,insulin and julolidine.The main research content is as follows:(1)We report a simple,low-cost,one-step synthesis of water-soluble luminescent carbon's microwave synthesis method,and surface functionalization imidazole as a novel fluorescence sensor.First,the carbon dots were heated by using citric acid and urea as raw materials,and then the imidazole was modified to the surface of the carbon dots to obtain a fluorescent nanomaterial carbon-imidazolequantum dot(CDs-imidazole)capable of detecting Ni²⁺.In inorganic solutions,the quenching of CDs-imidazole fluorescence by Ni²⁺is likely to be achieved by a dynamically bound photoinduced electron transfer mechanism.The fluorescence quenching efficiency of CDs-imidazolewith nickel ion concentration had good linear relationship between 6-100 m M,the detection limit is 0.93 m M,and can be used in the environmental detection of Ni²⁺.(2)A novel nanomaterial polyethylene glycol-sulfur quantum dot(PEG-SDs)was synthesized with polyethyleneglycol-400 as a passivating agent,sublimated sulfur was used as raw material and stirred at 70?for 45 hours.It has good water solubility and excellent light stability.Its morphology was characterized by transmission electron microscopy,and its spectral characteristics were characterized by ultraviolet absorption spectrum and fluorescence spectrum.Through optimization,the excitation wavelength of PEG-SDs was determined to be 400 nm,and the emission peak was located at 490 nm.Based on the fluorescence enhancement method to detect insulin,under the optimal experimental conditions,insulin concentration within the range of 43?346 u M has a good linear relationship with the fluorescence enhancementefficiency,and the detection limit is 11.71u M.The sensing system may be realized by the mechanism of photoinduced electron transfert,the fluorescence sensor platform can be used to detect insulin in insulin injection.(3)PEG-SDs were prepared by stirring for 160 hours at 70?through the simple condensation reflux method by using sublimed sulfur as raw materials.PEG-SDs were proved as an effective Fe³⁺fluorescence sensor and the limit of detection(LOD)was 2.51u M.Fluorescence of the PEG-SDs-Fe³⁺system could be strengthened by adding julolidine.The detection range and LOD of the julolidinewith PEG-SDs-Fe³⁺system were 2?40 u M and0.289 u M,which had a wider range and lower LOD compared with PEG-SDs.In addition,the fluorescence sensor can be used for the detection of Fe³⁺and juridine in water samples.