| Carbon dots?CDs?are quasi-zero-dimensional fluorescent nanoparticles with a carbon skeleton structure and a size of less than 10 nm.CDs have the advantages of strong fluorescence,good light stability,photobleaching resistance,small molecular weight and particle size,good biocompatibility,low toxicity,wide excitation spectrum and narrow emission spectrum.CDs are an ideal fluorescent material.However,the application of CDs mainly focuses on conventional biochemical detection and biological imaging.It is worth mentioning that probes for biochemical detection are often detected based on changes in the fluorescence intensity of the probe.It is susceptible to interference from probe concentrations,detection environments,and instrumentation.A new ratio fluorescent probe based on CDs can overcome the above problems and improve detection sensitivity.In drug delivery,the CDs drug delivery system has problems such as insufficient drug loading,large fluctuations in concentration after administration,short effective time,and inability to release the response to the environment.A fluorescent temperature sensitive hydrogel was prepared by combining long wavelength CDs with a temperature sensitive hydrogel.It can not only trace and observe the drug carrier,but also realize the responsive release of the drug by controlling the external temperature,thereby solving the problem of the sudden release of the existing drug dosage form.In addition,the application of CDs in other fields such as fingerprint development can be further extended.This thesis mainly uses the exploration of the previous literature and the research of the experiment to carry out the following four aspects.The first chapter introduces the overview,preparation,properties and applications of CDs.A brief introduction to the preparation of CDs includes top-down and bottom-up methods.It is mentioned that CDs have properties such as photoluminescence,up-conversion,photostability,fluorescence lifetime,and biocompatibility.The application of CDs in conventional fields such as chemical detection and biological imaging,as well as applications in various fields such as fingerprint development and fluorescent temperature sensitive hydrogels are described.In the second chapter,the blue-emitting CDs and the green-emitting cadmium telluride quantum dots were combined into a fluorescent probe pair to develop a novel ratio fluorescent probe.The effects of different pH,different concentrations of sodium chloride and time stability on the fluorescence intensity of the fluorescent probe were investigated.By optimizing the detection conditions,the ratio fluorescence probe achieves the recognition of silver ion?Ag+?specificity and sensitivity.The concentration of Ag+showed a good linear relationship with the probe in the range of3.10×10-14 M-7.06×10-14 M,and the detection limit reached 2.56 pM.In the third chapter,DL-malic acid and ethylenediamine were used as raw materials to synthesize green-emitting CDs?G-CDs?by one-step hydrothermal method.The effects of the types of CDs on the development of fingerprints were examined,and CDs suitable for fingerprint development were preferred.Various factors affecting the development of latent fingerprints,such as different objects,different pH and different development time,were explored.The best development conditions were selected.The development of the latent fingerprint was realized by using G-CDs as the fingerprint developing agent.The optical properties,surface groups and elemental compositions of G-CDs were studied by UV-visible absorption spectroscopy,fluorescence spectroscopy,X-ray photoelectron spectroscopy and fluorescence lifetime.Combining the previous research and existing characterization results,the mechanism of fingerprint development was discussed.In the fourth chapter,the fluorescent temperature-sensitive CDs/PNIPAM hydrogel was prepared by one-step synthesis in an oil bath at 70°C with G-CDs,acrylic acid andN-isopropylacrylamide?NIPAM?asthemainrawmaterials,N,N'-methylenebisacrylamide as the crosslinking agent and potassium persulfate as the initiator.The optical,temperature sensitive and pH properties of CDs/PNIPAM were explored by UV-visible absorption spectroscopy,fluorescence spectroscopy,infrared spectroscopy,transmission electron microscopy,Zeta potential and fluorescence microscopy.It has excellent biocompatibility,has potential application prospects in the fields of fluorescence imaging,fluorescent ink,drug delivery,further research on its application in pharmaceutical preparations will be further explored. |
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