Study On Synthesis And Application Of Sulfur-Selenium Doped Carbon Quantum Dots

Objective To synthesis the selenium-selenium-doped carbon quantum dots?S,Se-CQDs?with small particle size and high fluorescence quantum yield,research its application for detection of Cr???and the preliminary inquiry as a drug carrier for dopamine?DA?to penetrate the blood-brain barrier to promote the treatment of Parkinson's syndrome and other features.Method?1?The S,Se-CQDs were synthesized in one step by hydrothermal method using citric acid,mercaptoethylamine,and sodium selenite as raw materials and characterized by transmission electron microscopy?TEM?,X-ray energy spectroscopy?XPS?,Fourier infrared spectroscopy?FTIR?,and nuclear magnetic energy spectroscopy?NMR?.?2?To investigate the antioxidant properties of S,Se-CQDs through the DPPH test,hydroxyl radical scavenging test,H₂O₂ scavenging test and O₂·^-scavenging test,inspected its biocompatibility and distribution in cells by cytotoxicity test,zebrafish embryo experiments,and endocytosis experiments?3?S,Se-CQDs were used as fluorescent probes for the detection of Cr???through the principle of fluorescence quenching,and investigated its application in the detection of Cr???in Chinese herbal medicine and aquatic products or water samples.?4?Loading DA by amidation reaction using S,Se-CQDs as carrier?S,Se-CQDs-DA?,investigated the drug release behavior under the action of animal protease and the ability to penetrate the blood-brain barrier in vitro of S,Se-CQDs-DA.Results?1?The diameter of the synthesized carbon quantum dots was found to be about 6 nm by TEM analysis.It was proved that the carbon quantum dots contained-SH and Se by XPS,FTIR,and NMR analysis,indicating that the S,Se-CQDs were successfully synthesized.The fluorescence quantum yield of S,Se-CQDs was 45.4%.?2?The results of DPPH test showed that the clearance rate of active oxygen species of S,Se-CQDs reach 40%,they has a powerful ability to clear·OH and H₂O₂,and have a certain ability to remove O₂·^-.S,Se-CQDs have almost no toxic effects on cells and zebrafish embryos,they were easy to enter cells and gathered in the cytoplasm.?3?S,Se-CQDs were highly selective for the detection of Cr???,and have a good linear relationship at the concentration of 0-15mg/L.The linear equation is y=0.03544x+0.01092,R²=0.992,detection limit is 1.68n M.Using the S,Se-CQDs to detect Cr???in Chinese herbal medicine or aquatic products,the results were close to those of atomic absorption spectrophotometry.The recovery rate of Cr???in water samples is in the range of 90%-105%.?4?The drug loading rate of DA on S,Se-CQDs was4.3%.The release rate of DA reached 80%under the action of animal proteases and S,Se-CQDs-DA could cross the blood-brain barrier the amount of DA is 70%compared with the equivalent dose of levodopa.Conclusion The S,Se-CQDs with small size and high fluorescence quantum yield were successfully synthesized by hydrothermal.S,Se-CQDs have powerful antioxidant capacity,low toxicity and easy to enter cells,which make them have great application potential as biological antioxidant materials.S,Se-CQDs were highly selective for the detection of Cr???and can be used for the detection of Cr???in Chinese herbal medicine and aquatic products or water samples.S,Se-CQDs could cross the blood brain barrier and release DA smoothly under the action of enzymes.Therefore,it is preliminarily believed that S,Se-CQDs loaded with DA penetrate the blood-brain barrier to treat Parkinson's disease is feasible.