Study On Preparation And Application Of High Brightly Carbon Dots And Self-protective Room Temperature Phosphorescence Nanomaterials

Fluorescence and phosphorescence have been widely development and application in materials science,environmental science,biological sensing,medical and agricultural production and other fields.Fluorescence and phosphor new materials laid a solid material foundation for the development of fluorescence and phosphorescence analysis technology.With the rapid development of nano science and technology,fluorescent nanoparticles make a conspicuous figure as a kind of new fluorescent material in various fields.Carbon quantum dots is one of the hot research topic in recent years.Carbon quantum dots that have good water solubility,light bleaching,low toxicity,as well as good biocompatibility,is widely used in some fields,such as analysis of detection,biological imaging,photocatalysis;Room temperature phosphorescence has been widely used in life science,clinical medicine,environment and other fields since long life and wide stokes shift.However,The operating of oxygen removal limits the development and application of room temperature phosphorescence in a certain extent.Discovery and research of room temperature phosphorescence composite materials through self-assembly supramolecular system offers a new way for the development of room temperature phosphorescence.This paper not only studied hydrothermal preparation of fluorescent carbon quantum dot with using the different carbon source and applied to life ion sensing and cell imaging;Two crystalline nanoparticles were also prepared by synergic self-assembly of multi non covalent bonds weak force without operating of oxygen removal in suspension solution at room temperature and explored its mechanism of self-protection room temperature phosphorescence.The main contents of this paper are summarized as follows:?1?Reported a creative approach for preparation of high fluorescent carbon dots with bromophenol?pesticide residues?as precursor.We mainly studied the solvent dependence and temperature dependence of preparation of carbon dots.The results show that the higher content of organic solvent and higher carbonization temperatureis is advantageous to synthesis of the small size and high quantum yield carbon dots.At the same time,the carbon dots all has good water solubility,high stability and the ability to resist photobleaching.Aggregation and carbonization mechanism in the process of synthesis of carbon dots was deduced reasonably andinfered the untight structure of carbon dots through the room temperature phosphorescence method.And the preparation of carbon dots with pesticide residues as carbon source was simulated in the laboratory levels and used as colorless ink and fluorescent probe for printing pictures and cellular imaging.The results confirmed that the carbon dots have low toxicity,good biocompatibility and light stability.This method that the effective use of pesticides and other harmful chemicals for biomarkers and biological imaging probe has opened up a new way.?2?Reported fluorescence carbon dots was prepared through hydrothermal method with branched polyethyleneimine and citric acid as the carbon source.Optimal excitation and emission wavelength of carbon dots were 355 nm and 455 nm,respectively.It has maximum emission intensity when PH was 5.22.We found that Fluorescence of carbon dots aqueous solution are obvious response to Cu²⁺,Co²⁺,Fe3+ or other metal ions in neutral or alkaline,and only has obvious response to Cu²⁺under acidic condition?The copper amine complexes formed since Cu²⁺ can coordination with a large number of rich electronic amino on the surface of carbon dots so that the fluorescence quenching of carbon dots.Therefore,under acidic condition,carbon dots can be used as fluorescent probe for detection of Cu²⁺ in aqueous solution,and detection range was 0.02¹?M,which nearly with the previously reported detection range of fluorescent carbon dots through different methods with the same carbon source.?3?Reported the crystalline nanoparticles?CNs?that can emit room temperature phosphorescence were prepared through titrating the PbCl₂·4H₂O aqueous solution to 5-Isal ethanol solution,or titrating reciprocally 5-Isal ethanol solution and BPE dichloromethane solution without operating of oxygen removal.FT-IR spectroscopy and X-ray diffraction results showed that supramolecular co-crystals were prepared with 5-Isal and PbCl₂·4H₂O or BPE by synergic self-assembly of hydrogen bonding,?…? stacking and other non covalent bond interactions together.X-ray data revealed the same composition between CNs1 and Co-cry1;And because the solubility difference,and combined with high performance liquid chromatography?HPLC?proved that room temperature phosphorescence of CNs 2 came from 5-Isal,rather than Co-cry2 with nanometer size.In addition,we studied the room temperature phosphorescence properties of the co-crystals aqueous solution.Under the 375 nm excitation,Co-cry1 emited room temperature phosphorescence located at 505 nm and 545 nm,and Co-cry2 emited room temperature phosphorescence located at 528 nm.Due to the density structure of the crystalline nanoparticles or co-crystals,the dissolved oxygen was prevented to close to 5-Isal,which protected the inspire triplet of 5-Isal.Therefore,synergic self-assembly through multi weakly interactions in suspension solution have constructive significance to the development of self-protect room temperature phosphorescence of nanomaterials.