What is it about?

Graphene oxide (GO) is extensively proposed as an effective antibacterial agent in commercial product packaging and for various biomedical applications. However, the antibacterial mode of action of GO is yet hypothetical and unclear. Here we developed a new and sensitive fingerprint approach to study the antibacterial activity of GO and underlying mechanism, using Raman spectroscopy. Spectroscopic signatures obtained from biomolecules such as Adenine and proteins from bacterial cultures with different concentrations of GO, allowed us to probe the antibacterial activity of GO with its mechanism at the molecular level. Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as model micro-organisms for all the experiments performed. The observation of higher intensity Raman peaks from Adenine and proteins in GO treated E. coli and E. faecalis; correlated with induced death, confirmed by Scanning electron Microscopy (SEM) and Biological Atomic Force Microscopy (Bio-AFM). Our findings open the way for future investigations of the antibacterial properties of different nanomaterial/GO composites using Raman spectroscopy.

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Why is it important?

Escherichia coli (E. coli) and Enterococcus faecalis (E. faecalis) were used as model micro-organisms for all the experiments performed. The observation of higher intensity Raman peaks from Adenine and proteins in GO treated E. coli and E. faecalis; correlated with induced death, confirmed by Scanning electron Microscopy (SEM) and Biological Atomic Force Microscopy (Bio-AFM). Our findings open the way for future investigations of the antibacterial properties of different nanomaterial/GO composites using Raman spectroscopy.

Perspectives

Herewith, by using morphological and spectroscopic data we confirmed experimentally and theoretically that GO can induce the degradation of the outer and inner cell membranes of E. coli and E. faecalis bacteria. The work presented here demonstrates the great antibacterial action of GO is due to the release of Adenine and protein from Bacteria. Herein, we reported the exact mechanism at molecular level. The strategy can either be the use of GO as a Raman signal enhancer or the designed incorporation of GO in the novel antibiotics and other clinical applications. Antibacterial effects, bacterial inactivation and bacteriostatic effect of GO can be analysed by adjusting Raman signal. In future work, the size effect of GO on cytotoxicity will be investigated using Raman signal enhancer under relevant conditions. This will promote the use of GO in medical applications such as therapy, drug delivery and bio imaging in greater ways. Finally, the identified destructive extraction of Adenine and proteins offer a novel mechanism for GO antibacterial activity. Our finding will play a vital role in the design of new GO based antimicrobial materials.

Dr. Sitansu Sekhar Nanda
Myongji University

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This page is a summary of: Study of antibacterial mechanism of graphene oxide using Raman spectroscopy, Scientific Reports, June 2016, Springer Science + Business Media,
DOI: 10.1038/srep28443.
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