Design and characterization of Ni²⁺ and Co²⁺ decorated Porous Magnetic Silica spheres synthesized by hydrothermal-assisted modified-Stöber method for His-tagged proteins separation

The complete elimination of enzymes from the reaction mixture and the possibility of its recycling for several rounds result in great benefits, allowing the reduction of the enzyme consumption and their usability in continuous processes. In this work, it is evaluated the capture of a H6-tagged green fluorescence protein (GFP-H6) on porous magnetic spheres using the Co²⁺ and Ni²⁺ affinity adsorption as a possible cost-effective and up-scaled alternative way for the immobilization of His-tagged proteins. For this purpose, Porous Magnetic Silica (PMS) spheres were synthesized by one-step hydrothermal-assisted modified-Stöber method. The obtained spheres have a homogenous size distribution of 400nm diameter. The γ-Fe₂O₃ nanoparticles are homogenously distributed in the silica matrix. The obtained PMS spheres have a saturation magnetization of about 10emu/g. Magnetophoresis measurements show a total separation time of 16min at 60T/m. The obtained PMS spheres were successfully and homogenously decorated with Co²⁺ and Ni²⁺ and then evaluated for the capture of a GFP-H6 protein. The results were compared with the performance of the commercial beads Dynabeads® His-Tag Isolation & Pulldown.