Graphene Oxide/Carbon Nanotubes Aerogel For The Isolation Of Hemoglobin

Proteins play important roles in the life activities. It is of profound significance to develop rapid and efficient isolation methods to obtain proteins of high purity from complex sample matrices for ensuing proteomic analysis. In the present work, graphene oxide(GO)/carbon nanotubes(CNTs) aerogel is prepared and used as adsorbent for protein isoaltion, which not only provides a new protocol for the separation/purification of proteins, but also demonstrates the novel applications of GO/CNTs aerogel in life sciences.In the first part, a brief review is given to the methodologies used for the separation/purification of proteins. In addition, the properties and applications of GO and aerogel have also been discussed.In the second part, a solid-phase extraction procedure for the isolation of hemoglobin (Hb) from human whole blood is developed by using GO/CNTs aerogel as adsorbent. GO/CNTs aerogel is prepared by freeze-drying of homogeneous solutions of CNTs and GO sheets. The obtained GO/CNTs aerogel is characterized by means of FTIR, SEM, TEM and Zeta potential (surface charge analysis). The performance of the as-prepred GO/CNTs aerogel in the adsorption/isolation of Hb is thus investigated. At pH8.0, an adsorption of83%for100mg L-1Hb in a1.0mL solution is achieved by using0.1mg of GO/CNTs aerogel as sorbent, while nearly no adsorption of albumin is observed under the same condition, which offers the possibility for the selectively separate of Hb. Under the above adsorption conditions, the adsorption capacity of Hb onto GO/CNTs aerogel is2832.1mg g-1. The retained Hb could be recovered by using Britton-Robinson buffer of pH11.5as eluent, giving rise to a recovery of67%. Circular dichroism spectra indicate that the adsorption/desorption processes pose no effect on the conformation of Hb, showing favorable biocompatibility of the obtained GO/CNTs aerogel. The GO/CNTs aerogel is thus used for the selective isolation/purification of Hb from human whole blood. The results of sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE) indicate that high purity of hemoglobin is obtained.In the third part, GO aerogel is prepared by freeze-drying of homogeneous GO sheets solution. The obtained GO aerogel is characterized by means of FTIR, SEM and TEM. At pH6.0and an ionic strength of0.05mol L-1,100mg L-1Hb in a1.0mL solution is thoroughly adsorbed by using0.1mg of GO aerogel as sorbent, while the selectivity for proteins is not perfect. Under optimal adsorption conditions, the adsorption capacity of Hb onto GO/CNTs aerogel is better than CNTs, but not as good as that on GO aerogel.