The Study Of Synthesis And Properties Of Molecularly Imprinted Core-shell Nanomaterials

Molecular imprinting technique?MIT?refers to the preparation of a relatively mature technology for preparing functionally specific functional polymers?MIPs?for target molecules.The prepared molecularly imprinted polymer has the advantages of wide application range,high plasticity,good stability and excellent selectivity,especially its highly crosslinked rigid matrix,which is extremely advantageous for forming specific recognition sites,and can selectively and template Molecular binding for the purpose of selective recognition of target molecules.Quantum dots?QDs?is a class of quasi-zero-dimensional nanocrystals which has unique size dependence,high fluorescence intensity,narrow half-peak,and good stability.The novel molecularly imprinted fluorescence sensor prepared by using quantum dots as the light source will have the advantages of excellent optical properties of quantum dots and high selectivity of molecular imprinting,and has practical significance for specifically identifying high-risk pollution factors in complex systems.Antibiotics and phenolic substances are common high-risk pollutants in the environment.Improper treatment of wastewater in the chemical production process,leakage during the transportation of raw materials and non-standard medical use in underdeveloped areas have caused high-risk pollutants to flow into the environment,causing great harm to the environment and human health.Chloramphenicol has serious adverse reactions to the human hematopoietic system,causing human body marrow suppression and irreversible aplastic disorders.Symptoms like anemia,hypoplasia,platelets and leukopenia.Phenolic contaminants can cause genital disorders,abnormal behavior,decreased reproductive capacity,damage to the nervous system and immune system,death of larvae,and even extinction in animals.Therefore,the control and monitoring of these substances are particularly important based on the hazards of high-risk pollutants and the sustainable and renewable development of ensuring the health and environment of the people.The research uses quantum dots as a carrier to synthesize a molecularly imprinted fluorescence sensor with good selectivity and fluorescence performance through reverse microemulsion technology.The morphology,structure,composition and molecularly imprinted fluorescence sensor were studied by means of transmission electron microscopy?TEM?,Fourier transform infrared absorption spectroscopy?FT-IR?,and molecular fluorescence spectrophotometer,scanning electron microscopy?SEM?.Optical performance Fast,sensitive and reliable specific recognition of chloramphenicol and 2,4,6-trichlorophenol was achieved by fluorescence quenching.The specific research work carried out in this paper is as follows:?1?Determination of trace chloramphenicol in the environment by molecularly imprinted silica coated CdTe QDs fluorescence quenching method.Thioglycolic acid-modified CdTe QDs were synthesized by aqueous phase synthesis using thioglycolic acid?TGA?as a stabilizer.APTS was used as a functional monomer,TEOS was used as a cross-linking agent,and chloramphenicol was used as a template molecule.The molecularly imprinted sensing material was successfully prepared by reverse microemulsion technology and the fluorescence sensor?MIP@SiO₂@QDs?was successfully constructed.The morphology and optical activity of MIP@SiO₂@QDs were characterized by transmission electron microscopy,infrared spectroscopy,scanning electron microscopy and fluorescence spectrophotometer.The results show that the prepared sensor has a spherical shape,uniform particle size and high fluorescence emission intensity.The effects of pH and reaction time on the fluorescence of MIP@SiO₂@QDs were also investigated and the optimal detection conditions were determined.Fluorescence quenching experiments showed that the sensor had a good response to chloramphenicol,and the two showed a good linear relationship in the range of 1⁴00?mol/L.The detection limit was 0.35?mol/L.Selective experiments show that the prepared sensor has good selective recognition ability for chloramphenicol.It is used for the test of actual samples,and the recovery rate of the standard addition is satisfactory.?2?A novel fluorescence sensor based on molecularly imprinted silica microspheres coated with CdSe@CdS QDs was prepared and its detection of 2,4,6- trichlorophenolThe high-quality oil phase CdSe@CdS QDs modified by myristic acid/octadecene was synthesized under the condition of high temperature and anaerobic condition with 1-octadecene and myristic acid as ligands.The functional monomer APTS is then modified to the surface of the quantum dot so that the template molecule,2,4,6-trichlorophenol,can spontaneously assemble to the surface of the quantum dot by hydrogen bonding interaction.Then using the reverse microemulsion technology,using TEOS as the cross-linking agent and ammonia as the initiator,the molecularly imprinted fluorescence sensor MIP@SiO₂@QDs was prepared and the specific recognition of 2,4,6-trichlorophenol was established.The morphology and optical activity of MIP@SiO₂@QDs were characterized by transmission electron microscopy,infrared spectroscopy,X-ray diffraction,scanning electron microscopy and fluorescence spectrophotometer.The characterization results show that the prepared sensor has a spherical shape,uniform size and good dispersibility.The test results show that the prepared sensor has good selectivity,strong anti-interference ability,acid and alkali resistance and good stability.The concentration of 2,4,6-trichlorophenol showed a good linear relationship with the signal in the range of 5¹000?mol/L,the detection limit was 0.9?mol/L,and it has been successfully used for sensitive and rapid detection of 2,4,6-trichlorophenol in environmental water samples.