Synthesis Of Novel Nano-structured Imprinted Materials And Electrochemical Detection Of Drugs

Ketamine is a drug that has been abused for a long time and has a wide range of abuse.Fentanyl is one of the most toxic drugs that has emerged in recent years.The biological materials（blood,urine,saliva,etc.）usually contain drugs,there are a lot of interferences,which make the qualitative and quantitative analysis of drugs difficult.Therefore,it is of great significance to establish an accurate,sensitive,fast and high specific identification method for the detection of drugs.Molecularly imprinted polymers（MIPs）can be used in various occasions and complex environments due to their specific recognition cavity structure and memory identification function for the designated template molecules.By introducing nanomaterials,such as magnetic materials（Fe₃O₄）,covalent organic frameworks（COFs）,and graphene（r GO）,molecularly imprinted polymers can be endowed with some new functions and characteristics,which overcome the defects of polymers in magnetic conductivity and other aspects,increase the application range of polymers and improve the applicability of materials.In this paper,ketamine（KT）and alfentanil（AFEN）were used as detection objects,and Fe₃O₄,COFs,and carbon materials were used as carriers to prepare novel nano-imprinted polymers by surface molecular imprinting technology,which are used in electrochemical sensors detection research.The specific research contents are as follows:（1）The theoretical simulation was carried out in Gaussian software（Gauss 16）of the Windows system based on density function theory（DFT）.The molecular configuration of KT was optimized at the atomic level with the aid of Gaussian View5.0 program to obtain the stable molecular configuration of KT with the lowest energy and no imaginary frequency.The most suitable functional monomer species and imprinting ratio of KT-MIPs were gradually separated by computational simulation.KT was the template molecule,and methacrylic acid（MAA）,acrylamide（AM）,2-allyl-hydrophobic nicotinic acid（ANA）,acetamyl acrylic acid（AAA）were single functional monomers.The interaction between template molecule and functional monomer is studied,and the optimal functional monomer is selected.In addition,the number of binding energy hydrogen bond,the effective action site of bond length and the transformation trend of NBO charge were calculated at different imprinting ratios.The effective interaction mechanism between KT and functional monomers MAA,AM,ANA and AAA at different imprinting ratios can be studied at the small molecule level.Finally,the most suitable functional monomer for the preparation of molecularly imprinted polymer was selected as MAA,and the optimal polymerization ratio of KT/MAA was 1:4.（2）KT-Fe₃O₄-MIPs were prepared by surface imprinting polymerization,based on KT and MAA as template molecules and main functional monomers,ethylene glycol dimethacrylate（EGDMA）as cross-linking agent,the ration of KT:MAA:EGDMA as1:4:30,magnetic Fe₃O₄ nanoparticles as carrier material.The adsorption and selectivity of KT-Fe₃O₄-MIPs for KT were investigated by equilibrium adsorption experiments.The adsorption isotherm and kinetic adsorption curves were analyzed by Langmuir and Freundlich models.The results show that the theoretical maximum adsorption capacities of KT by Fe₃O₄@MIPs is 33.9905 mg·g^-1 and Fe₃O₄@NIPs is 15.7307 mg·g^-1.The binding sites on Fe₃O₄@MIPs are evenly distributed,and Fe₃O₄@MIPs has a strong selection ability and a specific recognition for the adsorption of KT.（3）The electrochemical sensor is constructed by modifying KT-Fe₃O₄-MIPs on the magnetic electrode.In 5.0 mmol·L^-1 K₃[Fe（CN）₆]solution(containing 0.1 mol·L^-1 KCl),the content of KT was determined by square wave voltammetry（SWV）,the adsorption of KT-Fe₃O₄-MIPs to KT is proved.The peak current showed a good linear relationship with KT concentration in the range of 1×10^-12～4×10^-4 mol·L^-1,and the detection limit was 8×10^-13 mol·L^-1.The constructed electrochemical sensor showed excellent selectivity and stability,and was applied to the determination of ketamine in domestic sewage with satisfactory results.（4）Covalent organic framework materials（COFs）were synthesized by microwave assisted synthesis and characterized by Fourier transform infrared spectroscopy（FTIR）,transmission electron microscopy（TEM）and scanning electron microscopy（SEM）.COFs@r GO/GCE electrode was constructed by COFs and reduced graphene oxide（r GO）,and the constructed electrochemical sensor was used for sensitive detection of AFEN.In the experiment,the PBS solution was 1/15 mol·L^-1 with p H of 7.38.The sensor had a good linear range for AFEN at 2×10^-8～7.26×10^-6 mol·L^-1.The detection limit was 6.7×10^-9 mol·L^-1.The sensor was successfully applied to the determination of alfentanil in urine.