Green Preparation And Optical Analysis Of Nitrogen Doped Fluorescent Carbon Dots

Carbon dots（CDs）is a new fluorescent carbon nanomaterial with a size less than10nm.Due to its unique optical properties,it has a good application prospect in the field of sensing and biomedicine.Currently,impovements are needed in synthesis of CDs due to environmental pollution,harsh conditions,and complicated operation.Meanwhile,to develop new synthesis methods of carbon dots are significative.Hence,two kinds of fluorescent carbon dots were prepared by electrochemical pulse potential method and electrochemical pre-oxidation-hydrothermal synthesis method.Based on the different properties of the two CDs,a specific and sensitive fluorescence sensor was constructed.The main study is as follows:A facile method using pulse potential carbonization of low-molecular weight organic compounds for CDs synthesis was introduced.In the mixture of o-phenylenediamine and ethanol,monodisperse N-CDs with excitation independent and solvation effects were obtained from mixture through an electrochemical oxidation.Furthermore,the effects of pH、high salt solution、metal ions on the carbon fluorescence of the synthesized N-CDs were studied.Under a wide pH range and high salt concentration,the carbon dots still has high fluorescence intensity and Fe³⁺has a well fluorescence quenching effect,which has the potential application for Fe³⁺detection.The N-doped blue fluorescent carbon dots were prepared by electrochemical preoxidation-hydrothermal combination treatment of sodium citrate and urea.The synthesized N-CDs have a narrow particle size distribution and high fluorescence intensity.Besides,the effect of pH and high salt solution on the fluorescence of carbon dots were studied,and the response of N-CDs to different metal ions was also studied.Specific detection of Fe³⁺can be achieved based on changes in fluorescence intensity of the probe,when the iron ion concentration is 0.01⁰.4μM,there is a good linear relationship between the fluorescence intensity of N-CDs and iron ion concentration,and the detection limit is46.6 nM,R²=0.9981.The response of the ABA antibody-labeled combinatorial carbon dots to the phytohormone ABA was studied by a chemical coupling reaction.Experiments shown that the antibody labeled carbon dots are better selective and sensitive to the phytohormone ABA,and there is a good linear relationship between ABA concentration and fluorescence intensity in the range of 0.08 to1.0 ng/mL.The detection limit is 23 pg/mL,R²=0.9942,it is expected to get a good application in the field of plants.