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RESEARCH PROFILE

Associate Professor Dr. Montree Sawangphruk

Chemical Engineering
School of Energy Science and Engineering (ESE)
Tel. +66(0) 33 014251
Email montree.s@vistec.ac.th
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Advanced Antimicrobial Materials and Products: Discovery of Antifungal Activity of Graphene Nanosheets

Graphene Oxide and Related Materials

The as-prepared GO and rGO materials were dispersed in acetone to a nominal concentration of 0.5 mg ml−1 (Fig. 1a). Exfoliated GO produced through the modified Hummers method had sufficient functional groups (e.g., epoxides, hydroxyls, carboxylic acids) to enable suspension in acetone. After reducing GO with hydrazine hydrate, rGO was harvested and re-dispersed in acetone using sonication. The rGO suspension shows black color produced by the removal of oxygen by reduction with hydrazine hydrate. The microstructures of rGO nanosheets were observed by optical microscopy (Fig. 1b), SEM (Fig. 1c) and TEM (Fig. 1d). The optical micrograph shows the transparent characteristic of rGO nanosheets on an oxidized Si substrate. The SEM image shows rGO nanosheets with average particle (lateral) size of less than 5 μm coated on the carbon substrate. The TEM image shows a few layers of rGO nanosheets with different lateral sizes. The nanosheets randomly overlap forming different edge graphitic layers.

Fig. 1 (a) Photograph showing the dispersion of rGO (left) and GO (right) in acetone, (b) optical micrograph, (c) SEM image and (d) TEM image of rGO nanosheets.

Antimicrobial Products/Prototypes

Antifungal activity of rGO nanosheets


Fig. 2 Mycelial growth of A. niger on the PDA media containing different concentrations of rGO (0–500 μg ml−1).


Fig. 3 Mycelial growth of A. oryzae on the PDA media containing different concentrations of rGO (0–500 μg ml−1).

 


Fig. 4 Mycelial growth of A. oxysporum on the PDA media containing different concentrations of rGO (0–500 μg ml−1).

The concentrations of rGO nanosheets, which can totally inhibit the mycelia growths of A. niger ( Fig. 2), A. oryzae ( Fig. 3), and F. oxysporum ( Fig. 4), are at 500, 500, and 250 μg ml−1, respectively. The reason, why the rGO nanosheets were effective to inhibit fungi, is probably due to the direct contact with the cell walls of fungi. After the contact, the reactive oxygen-containing functionalities of several small rGO nanosheets could chemically react with the organic functional groups of chitin and other polysaccharides on the cell walls of fungi. Notably, the antibacterial mechanism of graphene-related materials based on the direct contact with the bacterial cells was previously reported. It was also reported that the antifungal mechanism of essential oils containing oxygen-species functional groups (e.g., phenol) was due to the direct contact with the cell walls of fungi. Interestingly, it was recently reported that the cytotoxicity of GO nanosheets on A549 human cells occurred as a result of direct interactions between the cell membrane and GO nanosheets.

Coin Destructive extraction of phospholipids from cell membrane by graphene nanosheets

It has been found that graphene nanosheets can penetrate into and extract large amounts of phospholipids in the E. coli cell membranes. The strong dispersion interaction between hydrophobic graphene nanosheets and lipid molecule is a key driving force in killing and/or inhibiting the growth of bacterial cells. The recent study offers fundamentally understanding to the antimicrobial mechanism of graphene. The penetration of graphene into the cell membrane and subsequently the destructive extraction of phospholipids from the bacterial cell membrane is most possibly an exact antibacterial mechanism of graphene nanosheets. Experimentally microscopic and theoretical molecular dynamics simulation studies show that pristine graphene and GO nanosheets can induce the degradation of inner and outer cell membranes of E. coli via the interactions with phospholipids of bacterial cell membrane (See Figure 5 below). Graphene-based nanosheets can penetrate into and then remove large amounts of phospholipids from the cell membranes because of the strong interactions between graphene and lipid molecules. This destructive extraction leads to the death of bacterial cells.

        
Fig. 5 Cartoon showing the destructive extractions of phospholipids from E. coli cell membrane by graphene nanosheets

 

Selected Publications

  • S. Luanwuthi, A. Krittayavathananon, P. Srimuk and M. Sawangphruk, Rsc Advances, 2015, 5, 46617-46623.
  • M. Sawangphruk, Y. Sanguansak, A. Krittayavathananon, S. Luanwuthi, P. Srimuk, S. Nilmoung, S. Maensiri, W. Meevasana and J. Limtrakul, Carbon, 2014, 70, 287-294.
  • M. Sawangphruk, M. Suksomboon, K. Kongsupornsak, J. Khuntilo, P. Srimuk, Y. Sanguansak, P. Klunbud, P. Suktha and P. Chiochan, Journal of Materials Chemistry A, 2013, 1, 9630-9636.
  • M. Sawangphruk, P. Srimuk, P. Chiochan, T. Sangsri and P. Siwayaprahm, Carbon, 2012, 50, 5156-5161.
  • M. Sawangphruk, Y. Sanguansak, P. Suktha and P. Klunbud, Electrochemical and Solid State Letters, 2012, 15, F5-F7.
  • M. Sawangphruk, S. Pinitsoontorn and J. Limtrakul, Journal of Solid State Electrochemistry, 2012, 16, 2623-2629.
  • M. Sawangphruk, Graphene Science Handbook: Applications and Industrialization, CRC press, 2016, ISBN: ISBN 9781466591332.
 

Research Group Members:

Dr. Montree Sawangphruk (Assistant Professor)
Dr. Kanokwan Kongpatpanich (Lecturer)
Dr. Saran Kalasina (Postdoctoral Research Fellow)
Ms. Atiweena Krittayavathananon
Mr. Poramane Chiochan
Mr. Chan Tanggarnjanavalukul
Ms. Montakan Suksomboon
Mr. Nutthaphon Phattharasupakun
Ms. Juthaporn Wutthiprom
Ms. Siriroong Kaewruang
Mr. Jakkrit Khuntilo
Ms. Phansiri Suktha
Mr. Pawin Iamprasertkun
Mr. Tanut Pettong
Ms. Pichamon Sirisinudomkit
 

International Research Collaborator:

Department of Microbiology, Kasetsart University