Imprinting nanoparticles: Core-shell bovine hemoglobin (BHb) imprinted magnetic nanoparticles (MNPs) with a mean diameter of 210 nm have been synthesized for the first time. The imprinted magnetic nanoparticles could easily reach the adsorption equilibrium and magnetic separation under an external magnetic field, thus avoiding problems related to the bulk polymer. In this work, the core-shell bovine hemoglobin (BHb) imprinted magnetic nanoparticles (MNPs) with a mean diameter of 210 nm were synthesized for the first time. In this protocol, the initial step involved co-precipitation of Fe(2+) and Fe(3+) in an ammonia solution. Silica was then coated on the Fe(3)O(4) nanoparticles using a sol-gel method to obtain silica shell magnetic nanoparticles. Subsequently, 3-aminophenylboronic acid (APBA), which is the functional and cross-linking monomer, and poly(APBA) thin films were coated onto the silica-modified Fe(3)O(4) surface through oxidation with ammonium persulfate in an aqueous solution in the presence or absence of protein. The morphology, adsorption, and recognition properties of the magnetic molecularly imprinted nanomaterial were investigated by transmission electron microscopy (TEM), X-ray diffraction (XRD), thermogravimetric analysis (TGA), and vibrating sample magnetometer (VSM). Rebinding experiments were carried out to establish the equilibrium time and to determine the specific binding capacity and selective recognition. The protein adsorption results showed that poly(APBA) MIPs-coated magnetic nanoparticles have high adsorption capacity for template protein BHb and comparatively low non-specific adsorption. The imprinted magnetic nanoparticles could easily reach the adsorption equilibrium and magnetic separation under an external magnetic field, thus avoiding problems related to the bulk polymer. We believe that the imprinted polymer-coated magnetic nanoparticles can be one of the most promising candidates for various applications, which include chemical and biochemical separation, cell sorting, recognition elements in biosensors, and drug delivery.