Layer-by-layer assembled magnetic molecularly imprinted nanoparticles for highly specific separation of adenosine 5′-monophosphate: Relations between adsorption properties and imprinted layers

Molecularly imprinted polymers (MIPs) are an effective method to accurately recognize and isolate targets. Adenosine 5′-monophosphate (AMPs) are typical nucleoside compounds widely used as intermediates and raw materials in the pharmaceutical field with high medicinal potential. In this work, molecularly imprinted adsorbents with fast magnetic response recovery were obtained for the selective separation of AMP by covering MIPs with AcrU and AM as functional monomers and AMP as a template molecule on the surfaces of Fe3O4 NPs, and then by layer-by-layer (LBL) assembling of the MIPs realized through glutaraldehyde (GA) mediation. Static adsorption experiments have been utilized to explore the adsorption effects of different numbers of imprinted layers. The experimental results showed that the Fe3O4@MIPs-LBL2 covered with two layers of MIPs had the best imprinting effect (IF = 2.50), and the adsorption of AMP by Fe3O4@MIPs-LBL2 was dominated by chemisorption, with the saturation adsorption capacity reaching 105.72 μmol g−1, it could adsorb and separate AMP efficiently from the actual sample (human urine). The magnetic responsiveness solves the problem of difficult recovery and high recovery loss of nano-imprinted adsorbents. Notably, this work not only proposes a magnetic imprinted adsorbent for selective separation of AMP, but also explores the structure-effect relationship between the number of layers of MIPs and adsorption performance, which provides a new inspiration for improving the performance of molecular imprinting techniques.