Preparation Of N/P-doped Green Fluorescent Carbon Dots And Its Application In Food Detection

Carbon dots（CDs）is a novel type of nanomaterials with good luminescent properties with good biocompatibility,a wide range of raw materials,low cost,simple method,high photostability and other advantages.So they are widely applied in environmental detection,biological imaging,drug analysis,food detection,etc.In this paper,three kinds of N-doped green fluorescent CDs were prepared by one-step hydrothermal method,and their morphology,structure and optical properties were analyzed.The novel methods for the determination of ingredients in foods were provided.The main research contents are as follows:Chapter 1:The research of CDs was reviewed.Firstly,the advantages of CDs such as their composition and optical properties are summarized.Secondly,the preparation methods of CDs were classified.Finally,the applications of CDs in various fields were summarized.And the background and research content of this thesis were proposed.Chapter 2:Nitrogen-phosphorus co-doped CDs（N,P-CDs）were prepared by one-step hydrothermal method using p-phenylene diisocyanate,ethylenediamine and concentrated phosphoric acid as raw materials.the morphology and structure of the CDs were characterized,and the optical properties of the CDs were investigated.The CDs has good water solubility,and the optimal excitation and emission wavelengths are 392 nm and520 nm,respectively.And a novel fluorescence detection method for curcumin was established with the linear range of 3.50～242.24μM and the detection limit of 0.86μM.When the CDs were used for the detection of curcumin in actual water samples and chili powder flavoring,the recovery rate was in the range of 94.48%～105.82%,and the relative standard deviation was in the range of 0.17%～0.62%,which showing a good application prospect for the detection of curcumin in actual samples.Chapter 3:N-doped CDs（N-CDs）were prepared by one-step hydrothermal method with p-phenylene diisocyanate and diethylenetriamine pentaacetic acid as raw materials.The morphology and structure of N-CDs were characterized,and the optical properties of the CDs were explored.N-CDs has good water solubility,and the optimal excitation and emission wavelength are 373 nm and 545 nm,respectively.Moreover,a novel fluorescence sensor method with high selectivity for detecting Fe³⁺has been established with a linear range of 4.16～532.54μM and a detection limit of 7.65 n M because Fe³⁺can effectively quench the fluorescence of the N-CDs,Furthermore,the CDs were used to detect Fe³⁺in actual water samples and drink with the recovery rate of 96.62%～101.54%and the relative standard deviation of 0.09%～0.09%.The method is a more promising Fe³⁺detection method.Chapter 4:A nitrogen-doped green fluorescent CDs（N-CDs）wih high fluorescence quantum yield were synthesized by one-step hydrothermal method using m-phenylenediamine and diethylenetriamine pentaacetic acid as raw materials.The morphology and structure of N-CDs were characterized,and the optical properties of the CDs were investigated.The N-CDs have good water solubility,and the optimal excitation and emission wavelength are 442 nm and 515 nm,respectively.In this chapter,a novel fluorescence sensor method for the detection of VB₁₂was established with the linear range of 3.83～187.97μM and the minimum limit of detection of 3.62 n M.Moreover,the N-CDs were used for the detection of VB₁₂in actual samples.The recovery was in the range of94.48%～104.95%,and the relative standard deviation was in the range of 0.15%～0.84%.The established analytical method has a good application prospect in the detection of VB₁₂...