Synthesis Of Magnetic Nanoparticles Modified By Deep Eutectic Solvents And Their Applications

Epimedium is a representative traditional Chinese medicine with a history of thousands of years in China.It has the functions of promoting bone healing,antioxidation,and improving reproductive system functions.Flavonoids are the main active components of Epimedium,and are also the category components controlled by previous pharmacopoeia,occupying an important position in various research fields.However,due to the complexity of the types and structures of the characteristic flavonoids in Epimedium,as well as the low concentration of some components distributed in the body and the interference of biological substrates,it is difficult to accurately detect and analyze them.Sample pretreatment plays an important role in the accurate and quantitative analysis of target components in complex samples.This technology generally reduces interference through the enrichment,separation,and purification of target components to increase detection sensitivity,improve detection accuracy,and ensure experimental repeatability.Solid phase extraction（SPE）is a commonly used separation and enrichment technology that achieves the separation of target compounds from sample matrices and interfering compounds through the adsorption of the compounds to be separated by solid adsorbent.It is commonly used for the pretreatment and analysis of complex samples.However,traditional SPE technologies generally have low selectivity,low adsorption capacity,and cumbersome operations,resulting in slow processing and low efficiency.Therefore,developing new SPE methods with high selectivity,speed,and large adsorption capacity is a key research direction.Magnetic nanoparticles（MNPs）are a new type of adsorption material synthesized using magnetic nanoparticles as carriers and modified with different functional monomers on their surfaces.They have the advantages of high specific recognition ability,stable performance,rapid magnetic separation,and large adsorption capacity.They are often used as magnetic adsorbents for SPE pretreatment processes.In this study,a new magnetic adsorption material Fe₃O₄-CS-DES was synthesized and characterized for the detection of flavonoids in Epimedium.By optimizing the adsorption and elution conditions,MSPE-HPLC-UV quantitative analysis methods for Epimedium and biological samples were established,and were successfully used to enrich and detect flavonoids in them.The research work of this paper is mainly carried out from the following three aspects.Firstly,12 deep eutectic solvents（DES）were prepared,and the best DES was selected as the functional monomer.Using chitosan（CS）modified Fe₃O₄ as the carrier,a new environmentally friendly magnetic adsorption material Fe₃O₄-CS-DES was synthesized by precipitation polymerization.A series of methods were used to characterize the structure and morphology of the materials and explore the synthesis of polymers.The adsorption performance and reusability of the polymer were evaluated through adsorption isotherms,adsorption kinetics,and recovery experiments.Secondly,the adsorption and elution conditions of Fe₃O₄-CS-DES were optimized.Under the optimal conditions,a MSPE-HPLC-UV method was established for the enrichment and separation of five flavonoids from Epimedium from four varieties and18 habitats,and the content of these five flavonoids was determined.Through analysis and comparison,it was found that there were significant differences in the content of flavonoids in Epimedium from different varieties and habitats.This study provides a new method for the determination of the content of Epimedium,and provides a reference for the quality control of different varieties and habitats of Epimedium.Thirdly,taking blood,urine,and feces samples from male SD rats as the research object,the adsorption efficiency of Fe₃O₄-CS-DES for icariin in three biological samples was compared.The results showed that Fe₃O₄-CS-DES had the highest adsorption efficiency for icariin in urine.The adsorption and elution conditions of flavonoids in urine were optimized.Under the optimal conditions,an analytical method for the enrichment and detection of icariin in urine by Fe₃O₄-CS-DES was established,providing a new method for rapid and efficient enrichment and analysis of flavonoids from urine samples.