Magnetic metal oxide affinity chromatography-based molecularly imprinted approach for effective separation of serous and urinary phosphoprotein biomarker

Many phosphoprotein biomarkers have been proved to exist in body fluids such as serum and urine, however, there is absence of rapid and efficient separation and identification method. In this study, we proposed to combine metal oxide affinity chromatography (MOAC), molecular imprinting technology (MIT) and matrix-assisted laser desorption ionization time-of-flight mass spectrometry (MALDI-TOF MS) to establish an effective approach to solve this problem. To verify the feasibility of this approach, we selected a typical phosphoprotein lysozyme (Lys) as template and magnetic TiO2 as substrate to prepare the molecularly imprinted nanoparticles (denoted as Fe3O4@TiO2@Lys MIPs). A point worth noting is that polydopamine (PDA) as polymer layer made Fe3O4@TiO2@Lys MIPs more hydrophilic and biocompatible. Thanks to the recognition sites of phosphate and the template-shaped cavities, Fe3O4@TiO2@Lys MIPs showed great sensitivity (0.01 ng*mu L-1) and selectivity (Lysozyme: BSA: beta-casein = 1:100:100, mass ratio) in standard phosphoprotein solution. At the end, the Fe3O4@TiO2@Lys MIPs showed great separation ability to lysozyme phosphoprotein in both human serum and urine samples. Therefore, the MOAC-based molecularly imprinted approach is worthy to be expected in effective separation of phosphoprotein biomarker in complex body fluid, which will be a promising one in future.