Synthesis of Magnetic Fe3O4 Nanorings for BSA Protein Adsorption

The adsorption of bovine serum albumin (BSA) protein is important for protein research but remains a great challenge. Here, the hydrothermal method and calcination in a hydrogen-argon mixed atmosphere were used to obtain ordered mono-crystalline magnetic Fe 3 O 4 nanorings with controllable size and uniform structure, which were applied to the adsorption of BSA protein. The results showed that the magnetic Fe 3 O 4 nanorings prepared have the advantages of good crystallinity, controllable morphology, and excellent magnetic response. The Fe 3 O 4 nanorings had an outer diameter of ~160–180 nm, inner diameter of ~80–110 nm, and height of 70 to ~110 nm. The amount of BSA adsorbed by magnetic Fe 3 O 4 nanorings increased with increasing protein concentration; when the concentration of BSA was ~2.75 mg·mL -1 the adsorption amount approached saturation. When the pH value of the solution was ~5, the Fe 3 O 4 nanorings absorption of BSA was greatest. With increasing adsorption time, the amount adsorbed increased gradually. Adsorption equilibrium was reached after 3 h. According to the formula, the saturated adsorption capacity of BSA per gram of magnetic Fe 3 O 4 nanorings was 325.2 mg. Graphical Abstract .