Sep 20, 2012
Graphene-polymer nanocomposite kills bacteria on surfaces
Graphene can kill bacteria and prevent the formation of pathogenic and corrosive microorganisms, which makes it a potential candidate for antimicrobial coatings for surgical equipment other surfaces in various settings. Graphene can be hard to process on its own because the material tends to clump, but one way to get around this is to mix it with specific polymers. This allows graphene to disperse more readily in solution and coat surfaces more effectively.
Polymer nanocomposites with antimicrobial and biocompatible properties are of growing interest thanks to the variety of applications in areas such as biosensing and biomedical devices. Other uses include water treatment, for example, as membranes for water purification and disinfection. Currently, studies on biomedical, industrial and water-treatment applications of graphene-containing polymer nanocomposites have focused either on the material’s antimicrobial properties or on its human cytotoxity.
In order for these graphene-based nanocomposites to be used safely, they need to have both low mammalian toxicity and efficient antimicrobial characteristics. Researchers from the University of Houston and Case Western Reserve University have teamed up to prepare and characterize highly stable graphene (G) poly(N-vinylcarbazole) (PVK) dispersions and films for biomedical and industrial applications, reporting their results in the journal Nanotechnology.
The team led by Debora Rodrigues and Rigoberto Advincula prepared highly dispersed PVK-G (97/3 w/w %) nanocomposite solutions in various organic and aqueous solvents by solution mixing and sonication methods, while thin films were fabricated by electrodeposition. The antimicrobial property of the polymer nanocomposite was then tested against Escherichia coli (E. coli) and Bacillus subtilis (B. subtilis).
In the study, the scientists found that microbial growth after exposure to the nanocomposite PVK–G presented fewer viable and active bacteria compared with exposure to pure PVK or pure graphene solutions. Furthermore, the PVK–G thin film showed ~80% inhibition of biofilm formation while the PVK and the unmodified surfaces showed almost full coverage (i.e. >80 %).
The biocompatibility of the exfoliated PVK–G solutions on mammalian cells was evaluated and presented ~80% cell survival, which suggests that the polymer nanocomposite is highly biocompatible.
Overall the team’s results support the potential use of PVK–G for a wide variety of biomedical and industrial applications where bactericidal properties coupled with low cytotoxicity to mammalian cells are vital.
Additional details can be found in the journal Nanotechnology.
About the author
The investigation was conducted by research teams from the Civil and Environmental Engineering department at the University of Houston and from the Department of Macromolecular Science and Engineering at Case Western Reserve University. The teams are part of a collaborative research programme, which is focused on the development of nanocomposites for antimicrobial and anti-corrosive applications. This project was supported by the Research Experience for Teachers (RET) program (NSF Award No. 1130006) and the National Science Foundation Career Award (NSF Award No. 104093). Dr Catherine M Santos is a postdoc at the University of Houston. She performed the antimicrobial and biocompatibility tests on the polymer nanocomposite in solution and on thin-film coated surfaces. She was assisted by Farid Ahmed (a UH PhD student) and Alex Leon (a UH undergraduate student). Joey Mangadlao is a PhD student from Case Western Reserve University. He was responsible for the preparation and characterizations of the PVK-G dispersions and films. The PI leaders were Dr Debora F Rodrigues and Dr Rigoberto C Advincula. Dr Rodrigues is an assistant professor from the Civil and Environmental Engineering department at the University of Houston. She has been known to develop antimicrobial polymers containing carbon-based nanomaterial for environmental applications. Dr Advincula is a professor from the Department of Macromolecular Science and Engineering at Case Western Reserve University and his expertise is in macromolecular synthesis and fabrications.