Fabrication Of Molecularly Imprinted Polymers Based On Novel Cross-linkers For Pollutant Analysis

In order to achieve effective enrichment and separation of target pollutants in food,environmental and biological samples,researchers are dedicating to the design and development of various types of adsorbents.Owing to their numerous merits of simple preparation,low cost and outstanding adsorption selectivity,molecularly imprinted polymers(MIPs)have attracted extensive attention,and have been widely applied for the selective separation of target analytes from complex samples.Therefore,it is of great significance to develop MIPs with satisfactory binding capacity and specific recognition,excellent hydrophilicity and satisfactory biocompatibility.The content of cross-linker in imprinted network usually reaches 70%-90% so that the structure and properties of cross-linkers have an important effect on the adsorption performance of MIPs.Aiming at solving the problems of poor targets recognition in aqueous media,low selectivity towards target analytes and difficulty to degrade of MIPs,novel crosslinkers and various preparation technologies and strategies(i.e.surface imprinting,metal-chelation imprinting,and multi-functional monomers imprinting)will be introduced into the preparation of MIPs,combining with stimuli-responsive imprinting(i.e.magnetic-,solvent-responsive).And based on the constructed MIPs,analytical methods with highly enrichment ability and selectivity for target analytes in environmental,food and biological samples have been established.This paper not only effectively solved the above mentioned problems,such as poor selectivity in aqueous media,low adsorption capacity and complex preparation process of MIPs,etc.,but also enriched the types of existing cross-linkers,providing smart insights for the design and fabrication of MIPs with excellent adsorption properties,and offering ingenious ideas for establishing simple,fast and efficient analysis methods.This paper can be summed up as the following four parts:1.Magnetic MIPs(MMIPs)was synthesized on the surface of magnetic nanoparticles using hydrophilic triethylene glycol dimethacrylate(TEGDMA)as cross linker,methacrylic acid as functional monomer and sulfamethazine as template.The effects of the amount of cross-linker on the adsorption capacity and imprinting factor of MMIPs were investigated in detail.The results of single-and binary-adsorption experiments showed that the prepared MMIPs possessed higher specific binding ability towards sulfamethazine in aqueous media than that of traditional imprinted polymers prepared with ethylene glycol dimethacrylate as cross-linker.And the prepared MMIPs were successfully used for selective enrichment and separation of sulfamethazine in environmental water,achieving satisfactory analysis results.2.Two novel solvent-responsive MIPs(S-MIPs with bi-functional monomers and SMMIPs with magnetic and solvent dual responsiveness)were constructed by using TEGDMA as cross-linker integrating with the host-guest interaction between template and functional monomer for selective adsorption and separation of bisphenol A(BPA)in complicated samples(e.g.,environmental water,fruit juice and human urine).These two MIPs possessed high adsorption capacity and selectivity for BPA in aqueous media.This work effectively solved the problem of adsorption capacity and selectivity reduction caused by solvent difference between preparation and application conditions,and the eluent of solvent-responsive MIPs in the elution process was well consistent with the subsequent analysis process,which significantly simplified the extraction steps and improved the extraction efficiency.3.Benefiting from easy modification,wide availability and biodegradability,cellulose was often applied for preparation of the synthetic adsorbents.However,most of the prepared cellulose-based adsorbents failed to realize the adsorption selectivity for target analytes.Incorporating cellulose with imprinting technology not only can improve the biocompatibility of the constructed MIPs,but also would enhance the selectivity of cellulose-based materials towards target analytes and expand their applications.BPA-imprinted polymers(CMC-MIPs)were synthesized by thermallyinduced free radical polymerization using methyl acrylyl-modified carboxymethyl cellulose(CMC)and divinylbenzene as dual cross-linkers and styrene as functional monomer.The analytical method for BPA in milk with satisfactory recoveries and precision was established based on CMC-MIPs integrating with HPLC detection.4.Styrene-methyl acrylic acid copolymers were served as functional cross-linker instead of separate functional monomers or cross-linkers,which significantly simplified the raw materials composition of MIPs.The magnetic MIPs(Cu-CMMIPs)were constructed on the surface of carboxymethyl cellulose coated magnetic nanoparticles incorporating the surface imprinting and metal-chelating imprinting.Benefiting from the template perfectly matching the imprinted cavities,chelation interaction and multihydrogen bonding interaction between template and imprinted network,the prepared Cu-CMMIPs exhibited excellent adsorption capacity and selectivity towards template tetracycline,which was successfully used for the tetracycline analysis in environmental water with satisfactory recoveries and low limit of detection.The implementation of this work would inspire more insights on the fabrication of MIPs with high adsorption selectivity.