Purification of hemoglobin by adsorption on nitrogen-doped flower-like carbon superstructures.

Nitrogen-doped flower-like carbon superstructures (NPC-F) are prepared via carbonizing self-assembled polyimide nanosheets. SEM, TEM, XPS, and N2 sorption methods are adopted to characterize the flower-like structure. NPC-F exhibits adsorption selectivity for hemoglobin (Hb) because the specific pyridinic N groups of NPC-F could coordinate with the sixth vacancy of ferrous ion in hemoglobin. The adsorption behavior fits well with Langmuir model with a maximum adsorption capacity of 360.0 mg g-1 and the adsorbed Hb could be lightly stripped from the NPC-F nanospheres surface by 0.5 wt% CTAB solution. Circular dichroism spectra indicate no obvious conformation changing of Hb during purification process by NPC-F nanospheres. Five cycles of a continuous adsorption/desorption experiment demonstrate the reusability of NPC-F as adsorbent for Hb. The prepared NPC-F superstructures are then employed for the isolation of Hb from human whole blood sample, obtaining high-purity Hb as demonstrated by sodium dodecyl sulfate polyacrylamide gel electrophoresis assays. Graphical abstractNitrogen-doped flower-like carbon superstructure (NPC-F) is used to isolate target protein. NPC-F exhibits highly selective capture capacity towards hemoglobin because the specific pyridinic N groups of NPC-F could coordinate with the sixth vacant coordinating position of Fe2+ in hemoglobin.