Metal coordination assisted thermo-sensitive magnetic imprinted microspheres for selective adsorption and efficient elution of proteins

Protein recognition and separation with high efficiency, low cost and facile construction has been hampered by the deficient development of fabrication methods. Toward this issue, we proposed a functionally integrated strategy by combining metal coordination, thermo-sensitive building blocks and hollow Fe₃O₄@mSiO₂ microspheres (mSiO₂ referred as mesoporous silica) with molecularly imprinted polymers (MIPs), to realize selective adsorption and effective desorption of the targeted protein bovine serum albumin (BSA). Herein, a series of metal ions (Mn²⁺, Fe³⁺, Ni²⁺, Cu²⁺, Zn²⁺) were selected to chelate onto the surface of amino groups modified substrates to investigate the metal coordination effect, wherein Ni²⁺ exhibited the optimal BSA immobilization ability. Beneficial from the sufficient templates coordinated by Ni²⁺, our MSS@Ni²⁺-MIPs (represented Ni²⁺-involved imprinted microspheres) with well-designed composite structure showed the best rebinding performance (Q = 182.18 mg/g, IF = 4.78) and rapid adsorption equilibrium kinetics (30 min) at 32 °C. Although template proteins were seized by the strong metal coordination, we obtained the satisfactory elution efficiency (61.97 %) at 20 °C assisted with the swollen thermo-sensitive components. Based on this facile, smart and versatile imprinting approach, the well-defined materials would hold great promising in bio-applications.