Evaluation of Antibacterial Potential of Graphene Oxide Nanosheets and its Protein Functionalized Form

Abstract

It is tough to develop highly effective antimicrobial agents that are not harmful to humans and do not show adverse effects on the environment as well as economically favourable. Recently Graphene oxide nanosheets (GOns) have been reported as potential candidate for having antibacterial activity. In this present investigation, GOns was synthesized by pyrolysis of citric acid and characterized by UV- Vis spectroscopy, Field emission scanning electron microscopy, Raman spectroscopy and X-ray diffraction analysis. UV-Vis absorption spectra shows the characteristic peak of GOns around 235nm and FESEM shows the fairly regular and sharp edges of GOns. XRD analysis and Raman spectroscopy shows the nanostructure of GO with characteristic peak at 2?=10º (XRD) and ~1350cm-1, ~1600cm-1 (Raman spectroscopy). Further the toxicity of GOns and Lysozyme-GOns conjugate was assessed against human erythrocytes and the antibacterial effects were evaluated against two Gram-negative bacteria Escherichia coli and Pseudomonas aeruginosa and one Gram-positive bacteria Lactobacillus casei. The hemotoxcity of GOns was within 10%. Furthermore GOns reduced the growth in Gram-negative (P. aeruginosa) via ROS independent manner and acted as a growth enhancer for Gram-positive (L. casei). GOns functionalized with lysozyme increased the antibacterial effect as well as hemocompatibility. Results show that GOns has insignificant toxicity at high concentration against erythrocytes hence functionalised GOns can be safely used for antibacterial as well as biomedical applications.