The Synthesis Of Element-doped Fluorescent Carbon Dots And Its Application In Biomedical Analysis

Carbon-based materials have a wide range of applications and development prospects in the fields of chemistry,materials,industrial applications,and other interdisciplinary fields due to their environmental friendly properties.But they are difficult to become effective fluorescent carbon materials due to their lack of a suitable band gap.However,carbon dots(CDs)have good fluorescence characteristics which are composed of dispersed spherical carbon nanoparticles and their size is generally less than 10 nm.In the recent years,carbon dots have attracted the attention of scientific researchers after their initial discovery due to their excellent optical properties,high quantum yield,low synthesis cost,simple synthesis route,low toxicity and good biocompatibility.More and more studies have shown that carbon dots are a new type of spectroscopic probe following traditional semiconductor quantum dots and fluorescent dyes.They have a wide range of applications in the aspects of chemical and biological sensing,bioimaging,nanomedicine,photocatalysis and electrocatalysis.At present,there are various synthesis methods of carbon dots which have the advantages of low raw material price and simple synthesis method.But most of them also have some disadvantages such as energy consumption and expensive equipment.In order to establish a highly sensitive and low-cost analytical method,this article aims to prepare a new type of fluorescent carbon dots and discuss the synthesis process of carbon dots at room temperature.Then fluorescence spectrum analysis technology is used as the analysis and measurement method to make full use of the simple synthesis,low price of raw materials and good photobleaching resistance of carbon dots.In view of the current shortcomings of carbon dots in synthesis methods and biomedical analysis research,it is proposed to use element doping methods to carry out the following research contents:1.Nitrogen-doped carbon dots were synthesized at room temperature for the detection of tetracycline hydrochloride.In order to fit the concept of green synthesis and reduce the cost of testing,we used room temperature synthesis to synthesize nitrogen-doped carbon dots.However,considering that the synthesis method at room temperature generally required the addition of strong acid or base and took a long time,this study was based on the principle of amine-aldehyde condensation reaction to generate Schiff base by using glyoxal as the carbon source and o-phenylenediamine as the carbon source and nitrogen source.These two reactants were simply mixing and reacting at room temperature for 3 hours to generate yellow-green luminescent N-doped carbon dots.The synthesis route of room temperature synthesis of N-doped carbon dots was simple and easy to operate.The N-doped carbon dots also had excellent optical properties.Because the absorption band of tetracycline partially overlapped with the excitation band or emission band of N-doped carbon dots,the mechanism used to detect tetracycline could be inner filter effect(IFE).Therefore,it was a fluorescent probe with excellent properties that could be used to detect tetracycline hydrochloride.Finally,this method have been successfully applied to the detection of tetracycline content in tetracycline tablets.2.Preparation of Fe-doped carbon dots and intracellular imaging study of hypochlorous acid.Hypochlorous acid is a very important reactive oxygen species which is closely related to the development of many human diseases.The use of fluorescent probes to monitor the concentration changes of hypochlorous acid in biological samples in real time is of great significance for exploring and regulating the pathological process.A one-step solvothermal method was used to synthesize green fluorescent Fe-doped carbon dots.The absolute quantum yield of Fe-doped carbon dots was 23.8%.Fe-doped carbon dots had good light stability and emission independent of excitation characteristics.The synthesized Fe-doped carbon dots had a very good fluorescence response to hypochlorous acid.Therefore,the Fe-doped carbon dots were used for the detection of hypochlorous acid.The detection limit of this method was7.80 nmol/L which is more sensitive than many other fluorescence detection methods for hypochlorous acid.In addition,the Fe-doped carbon dots did not respond to many other cations and anions,especially to other reactive oxygen species.The Fe-doped carbon dots had good selectivity for detecting hypochlorous acid.In short,the advantage of this method for detecting hypochlorous acid was that it had high sensitivity and very good selectivity.Finally,we have also successfully used Fe-doped carbon dots for He La cell imaging,and then realized the exogenous and endogenous imaging of hypochlorous acid.In summary,this article developed a room-temperature synthesis method to synthesize nitrogen-doped carbon dots.We have realized the detection of tetracycline successfully with the help of fluorescence spectroscopy technology by using N-doped carbon dots as fluorescent detection probes.And then we continued to study the detection mechanism.Then,Fe-doped carbon dots were successfully synthesized by solvothermal synthesis method and used for the detection of hypochlorous acid and intracellular imaging.Fe-doped carbon dots have good selectivity and high sensitivity in hypochlorous acid detection.The detection method meets the basic requirements of analytical chemistry in the aspects of simple,fast and sensitive.The above research content provides a certain experimental basis for the room temperature synthesis research of carbon dots,and also expands the research scope of carbon dots in the field of synthesis and biomedical analysis.