(714d) Effect of Ethanol Solvent on Antimicrobial Efficiency of Magnesium Oxide Nanoparticles

Authors: 
Bhattacharya, P. - Presenter, Indian Institute of Technology Kharagpur
Neogi, S., Indian Institute of Technology Kharagpur

Effect
of Ethanol Solvent on Antimicrobial Activity of Magnesium Oxide Nanoparticles

Proma
Bhattacharya, and Sudarsan Neogi

Indian
Institute of Technology Kharagpur

Kharagpur
721302

Abstract:
The
emergence of different kinds of antibiotic resistant harmful microbes have led
to extensive research for development of novel antimicrobial agents. It has
been seen that different materials exhibit enhanced properties while in nano-scale
and for exploiting these properties for combating pathogens, nanoparticles are
very much appreciated. Different metal oxide nanoparticles such as zinc oxide,
copper oxide, calcium oxide, titanium dioxide etc.have been
investigated as potential antibacterial agents[1].
MgO is an inorganic compound with a significant band-gap, and it has already
found wide scope of applications like catalysis, harmful waste treatment, development
of refractories and adsorbents, different type of coatings with varied optical
properties, superconducting thin films, and lithium ion batteries, etc.
Recently, magnesium oxide nanoparticles have shown significant potential for
application in biomedical fields, especially tumour treatment and wound healing
due to its inherent antibacterial nature and ability to help in fibroblast
adhesion after a skin injury [2].
The reaction parameters for synthesis of MgO nanoparticles play an important
role in determining the morphology and properties [3].
In this work, the reaction solvent used is ethyl alcohol and its morphology and
surface and antibacterial properties of the nanoparticles are compared to those
synthesized in water. The particles were characterised by FESEM, EDX, XRD and
FTIR for studying their morphology and chemical composition. It has been found
that the size of the nanoparticles was greatly tuned by the solvent. The average
diameter of the water based nanoparticles was found to be 25 nm while it
changed to 10nm when the solvent was changed to ethyl alcohol. The surface
properties were analysed by its zeta potential measurement where it showed
marked change in the isoelectric point (point of zero charge) from 6.5 to 9
when the solvent is changed from water to ethanol. The evaluation of the
antibacterial efficacy of the nanoparticles prove an unexpected increase in
cell annihilation ability against both gram-positive (Staphylococcus aureus)
and gram-negative (Pseudomonus aeruginosa) bacteria. Colony forming unit
reduction tests reveal that a concentration of 5mg/ml of MgO prepared in
ethanol was able to reduce bacterial count by almost 99%. This concentration
was found to be haemocompatible (4% haemolysis), as indicated by the haemolysis
tests. To understand the mechanism of the cell-nanoparticles interaction, FESEM
imaging was done. The results infer that the ability of these nanoparticles to
penetrate and rupture the cell membrane, leading to gradual leakage of cell
components, to be the main reason behind their antibacterial nature. Amino acid
leakage studies are in coherence with this proposed mechanism. Thus, magnesium
oxide nanoparticles synthesized in ethyl alcohol are potential candidates for
wound healing as it is biocompatible as well as highly antibacterial.

Figure 1 Variation of zeta potential of the
nanoparticles synthesized in water and ethyl alcohol with pH of the solution

Figure 2 The percentage reduction of colony forming
units of S. aureus and E.coli with increasing concentration of MgO nanoparticle
synthesized in ethyl alcohol

(b)(a)    

Figure 3 FESEM images showing (a) untreated E.
coli and (b) E.coli treated with 5mg/ml of MgO in ethyl alcohol showing the
rupture of the cell after nanoparticle treatment leading to the leakage of
inter-cellular material

 

References:

 [1]    
Manke A, Wang L and Rojanasakul Y 2013 Mechanisms of nanoparticle-induced
oxidative stress and toxicity Biomed Res. Int. 2013

[2]      Jin T and He Y 2011
Antibacterial activities of magnesium oxide (MgO) nanoparticles against
foodborne pathogens J. Nanoparticle Res. 13 6877–85

[3]      Samodi A, Rashidi A, Marjani K
and Ketabi S 2013 Effects of surfactants, solvents and time on the morphology
of MgO nanoparticles prepared by the wet chemical method Mater. Lett. 109
269–74