Formation of hemoglobin assisted graphene oxide biocomposite film

Graphene oxide is a one-atom thick layer of graphite and has evolved as a promising precursor for preparing graphene-based composite materials with wide range of applications. Nowadays studies on the binding of biomolecules and nanoparticles with graphene oxide have become an interesting subject to researchers. In this paper, we report the interaction of graphene oxide with hemoglobin at the air-water interface by Langmuir-Blodgett and spectroscopic techniques. Study of the surface pressure growth kinetics reveals that an increased amount of graphene oxide in water subphase enhances surface activity of hemoglobin. The composite monolayers have been transferred onto glass substrate for characterizations by scanning electron microscopy, atomic force microscopy, Raman spectroscopy, UV-vis absorption and emission spectroscopy and circular dichroism. Studies show the decrement of α-helix with increasing concentration of graphene oxide with no major change in β-sheet, which suggests a modification of secondary structure of hemoglobin due to formation of hemoglobin graphene oxide complex. Hemoglobin changes its conformation in presence of the micro hydrophobic environment of graphene oxide sheet, thus forming the said complex at air-water interface. (author)