Recent advances of magnetic molecularly imprinted materials: From materials design to complex sample pretreatment

As a type of synthetic polymeric materials with selective recognition, molecularly imprinted polymers (MIPs), have possessed wide-ranging applications for selective separation and enrichment of targets analytes in complex sample matrix. However, when using MIPs as conventional solid phase extraction adsorbents for complex samples pretreatment, complex column packing is necessary, and it is not beneficial for large-volume samples operation. By combining the magnetic separation with MIPs, the constructed magnetic imprinted polymers (MMIPs) not only possess high adsorption selectivity for target analytes, but also bring significant convenience to the rapid separation of adsorbents and the processing of large-scale samples. In this review, we summarize advanced preparation strategies of MMIPs in recent years, including direct polymerization on magnetic nanoparticles (sol-gel process, dopamine self-polymerization, traditional polymerization and covalent reaction), polymerization on modified magnetic nanoparticles (magnetic nanoparticles modified with polymerizable groups, active groups, and hydrophilic layer, respectively) and polymerization on functionalized magnetic nanoparticles (magnetic nanoparticles functionalized with carbonaceous materials, natural materials and MOFs, respectively). Meanwhile, we highlight the utilization of MMIPs in sample pretreatment for targets analysis from complicated samples (food samples, environmental samples and biological samples). Finally, we evaluated the faced challenges and future trends in the field.