Preparation Of Nitrogen And Chlorine-doped Carbon Dots And Their Detection Of Tetracycline And Other Drugs

Carbon dot（CDs）is a new type of multicolor luminescent carbon nanoparticles,which is composed of carbon,hydrogen,oxygen and other elements.They are approximately spherical and have a size less than 10 nm.Because CDs have unique and novel characteristics,such as excellent water solubility,non-toxicity,easy functionalization,biocompatibility,and photobleaching resistance,they are widely used in chemical sensing,biomarking,and bioimaging,biocatalysis,photocatalysis and electrocatalysis and other fields.Chapter 1:A brief overview of CDs,the optical properties of CDs,the synthesis methods of CDs,and the applications of CDs.At the same time,the topic selection background,research content and innovation points are summarized.Chapter 2:Chapter 2:Using o-phenylenediamine and neutral red as raw materials to prepare nitrogen-chlorine-doped carbon dots（N,Cl-CDs¹）by hydrothermal method,they have bright orange fluorescence and the quantum yield（QY）is 5.3%.The surface morphology,structure,functional groups and optical properties of N,Cl-CDs¹were characterized by transmission electron microscopy（TEM）,infrared spectroscopy（FT-IR）,X-ray photoelectron spectroscopy（XPS）,ultraviolet（UV-Vis）and fluorescence（FL）.It is found that the N,Cl-CDs¹are spherical and show good dispersibility in water,with an average particle size of 2.15 nm,and the surface contains-OH,-NH₂and benzene ring structures.Under neutral conditions,the optimal excitation wavelength of the N,Cl-CDs¹is 390 nm,and the corresponding emission wavelength is 606 nm.As the p H value increases,the fluorescence increases,showing two linear segments between p H4.00-p H10.00,and the fluorescence is reversible.Based on the internal filtering effect between N,Cl-CDs1 and tetracycline（TC）,the fluorescence of N,Cl-CDs¹was linearly quenched with the change of TC concentration（0.05-130μM）,and the detection limit was3.9 n M.The N,Cl-CDs¹were used for the detection of TC in actual samples,and the recovery rate was 98.75-102.40%.Because the N,Cl-CDs¹have good biocompatibility,they have been successfully applied to the in vivo biological imaging of Oocystis.Chapter 3:Using riboflavin and neutral red as precursors,nitrogen and chlorine-doped yellow-green fluorescent carbon dots（N,Cl-CDs²）were successfully prepared by hydrothermal method,with a QY of 4.90%.The surface morphology,surface structure and optical properties of N,Cl-CDs²were characterized by TEM,FT-IR,XPS,UV-vis and FL.It is found that the N,Cl-CDs²is approximately spherical and has good dispersion in water with an average particle size of 2.80 nm.There are-OH,-NH₂and benzene rings on the surface.Under the condition of p H=11,the optimal excitation wavelength of N,Cl-CDs²is 370 nm,showing dual emission characteristics,and the corresponding emission wavelengths are 430 nm and 550 nm.Quercetin（QT）was selectively detected by N,Cl-CDs²by fluorescence.Based on the interaction between N,Cl-CDs²and QT,the fluorescence of N,Cl-CDs²was linearly quenched by QT in the range of 0.05-78μM,and the detection limit was as low as 1.2 n M.At the same time,N,Cl-CDs²was used for the determination of QT in the actual sample,the recovery was95.72-103.70%,and the RSD was less than 2.58%.Because the N,Cl-CDs²have good biocompatibility,they have been successfully applied to the in vivo bioimaging of Oocystis,showing the potential of organelle localization.Chapter 4:Using L-glutamine and triethanolamine as raw materials,nitrogen-doped blue fluorescent carbon dots（N-CDs）were successfully prepared by hydrothermal method,with a QY of 3.84%.A variety of characterization methods（TEM,FT-IR,XPS,X-ray diffraction（XRD）,UV-Vis and FL）have been used to show that the N-CDs is approximately spherical,has good dispersion in water,and has an average particle size of2.25 nm.The surface of N-CDs contains-NH₂and-OH groups.The optimal excitation wavelength of N-CDs is 350 nm,and the corresponding emission wavelength is 440 nm.The N-CDs can interact with tetracycline drugs（TCs:TC,chlortetracycline（CTC）and oxytetracycline（OTC））to produce different fluorescent signals.Based on this,there is a linear relationship between the fluorescence intensity ratio（F₀/F）of the N-CDs at 440 nm and the concentration of TC between 0.05-173?M,and the detection limit is 6.11Nm.At 420 nm,the linear range of the N-CDs fluorescence intensity ratio（F/F₀）and CTC concentration response is 0.05-14?M,and the detection limit is 2.21 n M.At 500 nm,I₅₀₀/I₄₄₀has a linear relationship with OTC in the range of 0.05-74?M,and the detection limit is 8.56 n M.At the same time,it is found that N-CDs and TCs will also have different responses under UV light.Based on this,a qualitative analysis method for TCs on filter paper is constructed.