Preparation, Characterization and Surface Functionalization of Nano Graphene Oxide Using Lysozyme: Evaluation of Antibacterial Activity Against Escherichia Coli

Abstract

A simple and environment friendly method controlled pyrolysis of citric acid and modified Hummer’s method had used for the synthesis of Graphene Oxide nanosheets (GOns). Here, the GOns are functionalized with hen egg white lysozyme protein by the process of chemical cross-linking results in formation of fGOns. The synthesized GOns was characterized using various standard biophysical techniques such as X-ray diffraction crystallography, UV-Vis spectroscopy, fluorescence spectroscopy, FESEM imaging, DLS particle size and zeta-potential analysis, DSC and TGA analysis. The XRD crystallography results showed a peak at 2O= 9.86° for pyrolysis synthesized GOns and 2O = 10.54° for modified Hummer’s synthesized GOns. The UV-Vis spectra showed a broad peak between 230-235nm for the GOns synthesized by two different methods. FESEM images shows the sharp edge shape of the GOns whereas, fGOns acquired spherical shape. The particle size distribution and zeta potential of GOns was measured. The fGOns was characterized by fluorescence spectroscopy as there is a decrease in fluorescence intensity for fGOns when compared to Lysozyme protein fluorescence confirms the binding of LYZ on GOns surface. The UV-Vis absorption spectra showed a peak shift around 225nm for the fGOns. Further, the effect of GOns and fGOns towards the growth kinetics of E.coli was evaluated by observing the E.coli growth profile and estimation of total intracellular protein concentration. Results showed that pyrolysis synthesized GOns and fGOns exhibiting bacterial growth inhibition during log phase of growth profile. Whereas, modified hummer’s synthesized GOns showed the enhanced growth of E.coli.