Preparation of bottlebrush polymer–modified magnetic graphene as immobilized metal ion affinity adsorbent for purification of hemoglobin from blood samples

An immobilized metal affinity (IMA) adsorbent was prepared by grafting bottlebrush polymer pendant with iminodiacetic acid (IDA) from the surface of polydopamine (PDA)-coated magnetic graphene oxide (magGO), via surface-initiated atom transfer radical polymerization (SI-ATRP). Poly(hydroxyethyl methacrylate) (PHEMA) was grafted firstly from the PDA-coated magGO as the backbone, and then poly(glycidyl methacrylate) was grafted from the PHEMA chains via the second SI-ATRP to afford the bottlebrush polymer-grafted magGO Thereafter, IDA was anchored on the nanocomposites to produce the IMA adsorbent after chelating copper ions. The adsorbent was characterized by various physical and physicochemical methods. Its adsorption properties were evaluated by using histidine-rich proteins (bovine hemoglobin, BHb) and other proteins (lysozyme and cytochrome-C). The results show that its maximum adsorption capacity to BHb was 378.6 mg g-1, and the adsorption equilibrium can be quickly reached within 1 h. The adsorbent has excellent reproducibility and reusability. It has been applied to selectively purify hemoglobin from human whole blood, indicating its potential in practical applications. Graphical abstract.