Preparation and characterization of uniformly sized molecularly imprinted polymers functionalized with core-shell magnetic nanoparticles for the recognition and enrichment of protein

A general method to prepare thin, molecularly imprinted polymer (MIP) coatings on magnetic Fe(3)O(4) nanoparticles (NPs) with a uniform core-shell structure for the recognition and enrichment of protein was developed. Four proteins (bovine serum albumin (BSA, pI = 4.9), bovine hemoglobin (BHb, pI = 6.9), bovine pancreas ribonuclease A (RNase A, pI = 9.4) and lysozyme (Lyz, pI = 11.2)) with different isoelectric points were chosen as the templates. The magnetic protein-MIPs were synthesized by combining surface imprinting and sol-gel techniques. The morphology, adsorption and recognition properties of the magnetic molecularly imprinted NPs were investigated by transmission electron microscopy (TEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy and through the use of a vibrating sample magnetometer (VSM). In comparison with the use of Lyz, BSA and RNase A as template proteins, BHb-imprinted Fe(3)O(4) showed the best imprinting effect and the highest adsorption capacity among the four proteins. The as-prepared Fe(3)O(4)@ BHb-MIPs NPs with a mean diameter of 230 nm were coated with an MIP shell that was 10 nm thick, which enabled the Fe(3)O(4)@BHb-MIPs to easily reach adsorption equilibrium. A high magnetic saturation value of 25.47 emu g(-1) for Fe(3)O(4)@BHb-MIPs NPs was obtained, which endowed the adsorbent with the convenience of magnetic separation under an external magnetic field. The resultant Fe(3)O(4)@BHb-MIPs NPs could not only selectively extract a target protein from mixed proteins but also specifically capture the protein BHb from a real sample of bovine blood. In addition, different batches of magnetic MIPs showed good reproducibility and reusability for at least six repeated cycles.