The Synthesis,Characterization Of Phosphorus And Nitrogen Co-doped Carbon Dots And Its Application As Label In Protein

As zero-dimensional carbon materials,carbon dots have drawn many attention owing to its unique optoelectronic properties.Heteroatom-doped carbon dots not only have fine dispersion in water,low toxicity and good biocompatibility like CDs,but also have highly photoluminescence quantum yield,excellent fluorescence stability and many functional groups.Herein,we prepared phosphorus and nitrogen co-doped carbon dots（P,N-CDs）using phytic acid and ethanediamine as precursors.We explored the effects of synthesis method and reaction condition on the fluorescence properties of P,N-CDs.Besides,we investigated the fluorescence stability and possibility as fluorescent label of P,N-CDs.The dissertation includes the following aspects:1.Synthesis and characterization of P,N-CDsA series of P,N-CDs were synthesized using phytic acid and ethanediamine as precursors under controlled reaction conditions by hydrothermal and microwave-assisted hydrothermal method,respectively.The P,N-CDs were characterized by scanning electron microscopy,transmission electron microscopy,atomic force microscopy,fluorescence spectrum,FT-IR Spectrum,UV-vis Spectrum and energy dispersive spectrometer,and also assessed the cytotoxicity by the MTT method.The results showed that the P,N-CDs possessesd highest photoluminescence quantum yield with microwave-assisted hydrothermal method and purified by dialysis（Φ=27%）.The morphology of P,N-CDs presents regular globular structures with 4.3 nm of the average particle diameter and 2.3 nm of thickness,and there are also have phosphate easter group and amino group on the surface.The cytotoxicity assays showed that cells still survivaling 84%with 400 mg/L P,N-CDs after 24 h.The results proved that the P,N-CDs possesses low toxicity,good biocompatibility,and excellent fluorescence stability.2.Study on the fluorescence stability of P,N-CDsWe studied the factors of physical and chemical which could impact the fluorescence stability of P,N-CDs.It was found that salinity,lighting time,amino acids,proteins,inorganic ions have no obviously effects on fluorescence intensity of P,N-CDs,except Cr₂O₇^2-has remarkable quenching effect.We build a new method according to the phenomenon.The method analytical ability for Cr₂O₇^2-is fine,and the detection Cr₂O₇^2-limit of 0.12?M.The P,N-CDs could be used to detect Cr₂O₇^2-which in natural environment.3.P,N-CDs as fluorescent labels for human immunoglobulin G detection in human serumDue to a great deal of phosphate easter group on the surface of P,N-CDs,which could be directly activated by EDC-NHS,P,N-CDs tend to cross linked with N-terminal of amino acid readily.P,N-CDs were thus labelled in goat anti-human immunoglobulin（g Ig G）.The obtained P,N-CDs/g Ig G still kept higher fluorescent quantum yield of 14%.Through specific binding by antigen-antibody,P,N-CDs/g Ig G were used for the detection of human immunoglobulin G in human serum with satisfactory results.