Preparation Of Diethylstilbestrol Molecularly Imprinted Polymers And Their Application In Water Quality Testing

Diethylstilbestrol(DES)is an environmental estrogen that can be accumulated in environmental water through medicinal use in aquaculture and excretion by humans and animals.Very low concentrations of DES in environmental water can cause functional feminization and immune function changes in aquatic organisms,and increase the risk of cancer in humans.Therefore,it is imperative to synthesize a new type of function materials for the enrichment and separation of the DES residues accurately and quickly in environmental water,and further to establish a new technique with good selectivity and high sensitivity,thereby enabling simple detect the DES residues succinctly.Molecularly imprinted technology refers to the preparation of polymers that exactly match a target compound(template molecule or imprinted molecule)in terms of spatial configuration and binding sites.The molecularly imprinted polymers(MIPs)synthesized by this technique have many advantages,such as structural predictability,specific recognition,and wide application.In recent years,molecularly imprinted technology has also been applied to the detection and removal of contaminants in wastewater and drinking water.In this study,DES was used as the target molecule;methacrylic acid(MAA),acrylamide(AM),3-Aminobenzeneboronic acid(APBA),and 1,2-diaminobenzene(OPD)were as the functional monomers;ethylene dimethacrylate(EDMA)and divinylbenzene(DVB)were as the crosslinkers;methanol,acetonitrile,and water were as the solvents.The stable complexes of DES with the four monomers were simulated by the LC-ωPBE/6-31G(d,p)method.The stable complex configuration of DES with four monomers was simulated and calculated to screen the best functional monomers,cross-linkers,and solvents for the synthesis of DES-MIPs and to explore the mechanism of DES imprinting.The calculated results showed that DES-MAA complex formed hydrogen bond.When the acetonitrile was as the solvent,the EDMA was selected as the cross-linking agent,and the molar ratio between DES and MAA was 1:5,the stable complexes of DES-MIPs with the lowest energy was the most stable.Then,DES-MIPs were prepared by precipitation polymerization method guided by the theoretical calculation,and the affinity and selectivity of DES-MIPs were investigated by static adsorption,dynamic adsorption,and selective adsorption.The experimental results showed that the DES-MIPs had regular particles with homogeneous morphology and the particle size ranged from 105 to 260 nm;the maximum adsorption capacity of the polymer to DES was 60.17 mg/g,and the kinetic adsorption was in accordance with the quasi-secondary kinetic model.The DESMIPs showed excellent selective adsorption of DES in both single and binary adsorption systems.Finally,the DES-MIPs-quartz crystal microbalance(DES-MIPs-QCM)sensor was constructed by encapsulating the DES-MIPs prepared with the calculated results on the QCM electrode.The response parameters of the sensor were also optimized to explore the selectivity of the sensor,and it was applied to detect the content of DES in water samples.The results showed that the sensor had a high binding affinity for DES when the DES-MIPs was added at 15 mg and the coating volume was 10 μL.The minimum limit of detection of the sensor for DES was 2.63 ng/m L in the range of 50 ～ 350 ng/m L.The molecularly imprinted QCM sensor showed high recognition ability for DES compared with the structural analogs bisphenol A,estriol and estrone.The recovery rates of sensor were in the range of 91.73% ～ 98.54% for seven test in water samples.