The Application Of Ionic Liquid And Deep Eutectic Solvent Functionalized Composites In The Separation And Analysis Of Proteases And Pollutants

Magnetic solid-phase extraction(MSPE)is a sample pretreatment technology based on solid-phase extraction that uses magnetic materials as extractants.The extractants can be easily collected by an external magnet,without cumbersome centrifugation and filtration steps.Therefore,MSPE can be applied for the pretreatment of high-throughput samples and is easy to realize industrialization.Ionic liquid(IL)is molten salt composed of organic cation and organic or inorganic anion.Deep eutectic solvent(DES)is eutectic mixture formed by hydrogen bond donor and hydrogen bond acceptor through hydrogen bond interaction.By adjusting the anion and cation structures of IL,or hydrogen bond donor and hydrogen bond acceptor structures of DES,"tailor-made"IL and DES with specific functions can be synthesized.Based on this,IL and DES are used to replace traditional organic solvents as modified reagents for the functionalization of composites,which can not only synthesize extractants with specific binding capacity for target analytes,but also give play to"green solvent"property of IL and DES.It effectively reduces the secondary pollution introduced during the synthesis process,and is more in line with the concept of green analytical chemistry.Thus,the synthesis strategy based on IL and DES provides new ideas for designing efficient MSPE extractants.In this study,a variety of ILs and DESs were synthesized and combined with MSPE to construct selective separation and analysis methods of?-chymotrypsin,lysozyme,dyes,and pharmaceuticals and personal care products.The main research contents are as follows:(1)Ionic liquid modified magnetic metal-organic frameworks composites for the solid-phase extraction separation analysis of?-chymotrypsin1-hexyl-3-methylimidazolium chloride ionic liquid modified magnetic multi-walled carbon nanotubes supported by metal organic frameworks composite(Fe₃O₄-MWCNTs-OH@ZIF-67)was synthesized,and combined with MSPE for the extraction of?-chymotrypsin.Initial?-chymotrypsin concentration,ionic strength,extraction time,extraction temperature and solution p H all influenced the extraction capacity of Fe₃O₄-MWCNTs-OH@ZIF-67 toward?-chymotrypsin.Under optimized extraction conditions,the extraction capacity reached up to 635 mg·g^-1,which was much higher than that of ovalbumin,bovine serum albumin and bovine hemoglobin.The elution rate of phosphate buffer with p H of 12 for?-chymotrypsin was 86%,and the enzymatic activity of eluted?-chymotrypsin still retained 93%of initial activity.The regenerated Fe₃O₄-MWCNTs-OH@ZIF-67@IL can be reused several times and kept a high extraction capacity.The proposed method can be successfully used for separation analysis of?-chymotrypsin from the crude extract of porcine pancreas.(2)Ionic liquids skeleton typed magnetic core-shell molecularly imprinted polymers for the specific recognition of lysozyme1-vinyl-3-aminoformylmethyl imidazolium chloride ionic liquid([VAFMIM]Cl-IL)and 1,6-hexanediyl-3,30-bis-1-vinylimidazolium dichloride ionic liquid([HBVMIM]Cl-IL)were synthesized.Choosing[VAFMIM]Cl-IL as double bond functionalization reagent and functional monomer,[HBVMIM]Cl-IL as cross-linker,[VAFMIM]Cl-IL modified carboxyl functionalized iron oxide as substrate materials and lysozyme as template protein,ionic liquids skeleton typed magnetic core-shell molecularly imprinted polymers(Fe₃O₄-COOH@IL-MIP)were constructed via surface-imprinting technique,and utilized for specific recognition of lysozyme.Mechanism exploration indicated that Fe₃O₄-COOH@IL-MIP extracted lysozyme through synergistic effect of electrostatic interaction,cavity memory and various interactions introduced by ILs.The maximum extraction capacity was 166.36mg·g^-1 and imprinting factor was 2.67.Fe₃O₄-COOH@IL-MIP can be reused ten times without obvious loss of extraction capacity.The lysozyme conformation maintained intact after elution and the elution rate was as high as 74%.This method can effectively separate and analyse lysozyme of egg white.(3)Poly(deep eutectic solvent)-functionalized magnetic metal-organic framework composits coupled with solid-phase extraction for separation analysis of cationic dyesPoly DES composed of 3-acrylamidopropyl trimethylammonium chloride and sorbitol functionalized magnetic metal-organic framework composite(Fe₃O₄-NH₂@HKUST-1@PDES)was synthesized,and combined with MSPE for selective separation of malachite green(MG)and crystal violet(CV).A response surface methodology(RSM)was selected to optimize initial concentration of dyes,extraction time,solution pH and extraction temperature.The maximum extraction capacity predicted by RSM model matched well with actual experimental results,and it was 966.93 mg·g^-1 for MG and 788.90 mg·g^-1 for CV under optimum extraction conditions.The electrostatic interaction between Fe₃O₄-NH₂@HKUST-1@PDES and cationic dyes played the main roll in extraction process.The extraction process of Fe₃O₄-NH₂@HKUST-1@PDES toward MG tended to be a heterogeneous multilayer extraction-adsorption,while toward CV was typical monolayer extraction-adsorption.Spiked recoveries of fish samples at three spiking levers ranged from 89.43%to100.65%for MG and 95.29%to 98.03%for CV.(4)Deep eutectic solvent stabilized magnetic polydopamine combined with solid-phase extraction for di-selective separation analysis of mixture dyesThree DESs based on methacrylic acid and quaternary ammonium salts stabilized magnetic polydopamine extractants(MPDA-PDES)were synthesized and used for selective separation of target dye from malachite green(MG)and sunset yellow(SY)binary dye solution.The addition of Ca Cl₂ in separation system realized the dynamic transformation process from selective separation of MG to selective separation of SY,and selectivity factor was reduced from 37.57 to 0.30.The MPDA-PDES extractant exhibited strong anti-interference ability and good regeneration performance.It can be used for six times and extraction capacity remained basically unchanged.Mechanism exploration manifested that synergistic effect of electrostatic interaction,hydrophobic interaction,hydrogen bonding and ?-? stacking between MPDA-PDES and dyes made polydopamine stabilized by DES containing long-chain alkyl groups exhibited good selective separation ability to cationic dye in binary dyes solution.The separation of dyes in synthetic wastewater suggested that MPDA-PDES can be successfully used for selective removal of target dyes in actual wastewater.(5)Separation of pharmaceuticals and personal care products by deep eutectic solvents-regulated magnetic metal-organic framework extractantsSeven DESs composed by quaternary ammonium salts and carboxylic acids regulated magnetic metal organic framework composites(DES-MUi O-66-NH₂)were synthesized,and combined with MSPE for selective separation of five pharmaceuticals and personal care products(PPCPs).The separation process of DES-MUi O-66-NH₂ toward PPCPs was well fitted with Langmuir isotherm model and pseudo-second-order kinetics model,indicated that the separation of PPCPs occured on homogeneous surface of DES-MUi O-66-NH₂.Under the optimal conditions,the extraction capacity of DES-MUi O-66-NH₂ toward ofloxacin and mefenamic acid was97.60 and 79.22 mg·g^-1,respectively.DES-MUi O-66-NH₂ exhibited excellent anti-interference ability,reproducibility and reusability,can repeatedly extract PPCPs six times,and the extraction capacity remained basically unchanged.Mechanism exploration indicated that DES-MUi O-66-NH₂ selectively extracted PPCPs through electrostatic interaction,chelation,?-? stacking,hydrophobic interactions and hydrogen bonding.Density functional theory further proved the existence of chelation.The investigation of structure-activity relationship manifested that structures of DESs directly determined the separation specificity of DES-MUi O-66-NH₂ for PPCPs.The proposed method provided new ideas for designing efficient extractants for PPCPs.