The Preparation And Application Of Functionalized Magnetic Nanoparticles Based On Aptamer In Sample Pretreatment

Magnetic nanoparticles(MNPs)have outstanding properties,such as large specific surface area,strong magnetic susceptibility,ease of preparation,and low toxicity,and have been widely used in environmental and food analysis.As a novel solid phase extraction method,magnetic solid phase extraction(MSPE)based on representative nanoparticles Fe3O4,features high extraction efficiency,high sensitivity,ease of operation,low cost,and is easy to couple with other chromatographic systems to achieve automated online analysis.Fe3O4 MNPs modified with special functional groups can be applied to extract the target analytes selectively,and they can be separated easily and quickly with the assistance of an external magnetic field,making the sample pretreatment and enrichment process easy and rapid.In addition,the magnetic nanoparticles can be recycled,which is environmentally friendly and resources saving.Nucleic acid aptamers have the advantages of high affinity,specificity,low molecular weight,and ease of chemical modification.They can bind to target molecules through hydrogen bonds,electrostatic,stacking,and hydrophobic interactions to build stable three-dimensional space structures.In this work,combining the specific identification and recognition of nucleic acid aptamers with the excellent performance of magnetic nanoparticles,two aptamer-based magnetic nanoparticle adsorbents were successfully fabricated by hydrothermal synthesis method.Two online MSPE-high performance liquid chromatography-mass spectrometry(online-MSPE-HPLC-MS)methods were developed for the measurement of trace metabolites in the human urinary samples.The project conception and research contents are as follows:1、Fe3O4-aptamer magnetic nanoparticles(Fe3O4-aptamer MNPs)were successfully prepared by hydrothermal synthesis and glutaraldehyde cross-linking reaction.Based on the Fe3O4-aptamer sorbent,a new online-MSPE-HPLC-MS method was established to detect 8-hydroxy-2’-deoxyguanosine(8-OHdG)in urine.Benefiting from the high affinity of 8-hydroxy-2’-deoxyguanosine aptamer and the large specific surface area of nanomaterials,the prepared magnetic nanosorbents exhibit desirable advantages such as high extraction efficiency,good selectivity.In addition,to some extent,the as-prepared sorbents can resist matrix interference.When compared with offline manual mode,online extraction mode showed faster analysis speed,easy automation,good reproducibility and high sensitivity,which can reduce the human operation errors effectively.The relevant parameters were optimized in the experiment.Under the optimal experimental conditions,the limits of detection was 0.01 ng mL-1,the linear range was 0.05-200 ng mL-1,good linearity with excellent linear correlation coefficient(R2)being larger than 0.9992)were received.Moreover,the repeatability as relative standard deviations values ranged from 2.2%to 10.5%,and the recoveries of the 8-OHdG were obtained in the range of 82%to 116%.The experimental results show that the proposed online-MSPE-HPLC-MS method has the advantages of rapid analysis,automation,good repeatability and high sensitivity.It can be used to detect 8-OHdG in urine and is expected to become a promising approach for the determination of trace 8-OHdG in complex biological samples.2、The aptamer-based magnetic adsorbent(Fe3O4@PDA-aptamer MNPs)was prepared by hydrothermal synthesis and surface functionalization method,and a novel online-MSPE-HPLC-MS method was developed for the determination of 8-hydroxy-2’-deoxyguanosine(8-OHdG)and hydroxyl ated polycyclic aromatic hydrocarbons(OH-PAHs)simultaneously in urine.Due to the large specific surface area of modified magnetic nanoparticles and strong affinity of aptamer,affinity-specific adsorption of 8-OHdG and non-specific adsorption of OH-PAHs can be achieved at the same time.Under the optimal test conditions,satisfactory sensitivities with the limits of detection in the range of 0.028-0.114 ng mL-1 and good linearity with the correlation coefficients(R2)being larger than 0.9962 had also been obtained.The relative standard deviations values were lower than 16.1%and the recoveries of 8-OHdG and OH-PAHs ranged from 71%to 116%.The above results show that the proposed online-MSPE-HPLC-MS method possessed the advantages of rapid,sensitive and automated,it has potential application in the simultaneous determination of 8-OHdG and OH-PAHs in complex sample matrix to assess the environmental exposure level.