Journal of Basic Applied Sciences, 2016, 12, 205-210 205 [623162]

Journal of Basic & Applied Sciences, 2016, 12, 205-210 205

ISSN: 1814-8085 / E-ISSN: 1927-5129/16 © 2016 Lifescience Global Synthesis and Characterization of Zinc Oxide Nanoparticles for
Antibacterial Applications
S. Naseem Shaha,*, S. Imran Alib, S. Rizwan Alia, M. Naeema, Yasmeen Bibic,
S. Rehan Alia, S. Masood Razaa, Yousuf Khand and Sikander Khan Sherwanie
aDepartment of Physics, Federal Urdu University of Arts, Sciences and Technology, Karachi, Pakistan
bDepartment of Applied Chemistry and Chemical Technology, University of Karachi, Karachi, Pakistan
cDepartment of Chemistry, Federal Urdu University of Arts, Sciences and Technology, Karachi, Pakistan
dCentralized Science Laboratory, University of Karachi, Karachi, Pakistan
eDepartment of Microbiology, Federal Urdu University of Arts, Sciences and Technology, Karachi, Pakistan
Abstract: ZnO nanoparticles are synthesized for antibacterial applications by a simple co-precipitation method. X-ray
diffraction (XRD) reveals that the synthesized ZnO has hexagonal crystal structure with mean crystallite size of 29 nm.
Scanning electron microscopy (SEM) and Energy dispersive x-ray spectroscopy (EDX) shows pure ZnO with uniform
morphology. UV–VIS absorption spectroscopy yield an absorption edge in the range 300-400 nm which corresponds to a band gap energy of 3.50 eV. Antibacterial activity of ZnO nanoparticles is tested against gram positive and gram
negative bacteria by using agar-well method. These ZnO nanoparticles are found to be strongly antimicrobial as they
effectively prevent the growth of many test microorganisms with a small minimum inhibitory concentrations (MIC) ~ 80 – 280
g/ml.
Keywords : Nanoparticles, Chemical synthesis, Zinc oxide, Optical property, Antibacterial activity.
INTRODUCTION
Outstanding optical absorption features of ZnO and
its biocompatibility have resulted in many modern day
cosmetic products employing ZnO nanoparticles as key
ingredient [1,2]. These include lotions, ointments, medicated creams and sunscreens etc. In this context, the remarkable antimicrobial properties ZnO are also of relevance especially for medical and biological applications [3,4]. Additionally, due to successive use
of antibiotics, microorganisms have developed
immunity against them. This situation certainly demands new antibacterial compounds such ZnO
based on advanced functional materials [5].
It has been shown that ZnO nanoparticles exhibit
antimicrobial activity against a number of microorganisms [6,7]. To realize the full potential of ZnO as an antimicrobial agent, controlled and cost-
effective synthesis of pure, uniform (monodisperse)
and crystalline ZnO nanoparticles is of prime importance. A low-cost and simple synthesis with a high yield will guarantee successful commercialization of the product. Synthesis of nanoparticles via chemical methods has already been employed for producing
advanced functional nanomaterials exhibiting better

*Address correspondence to this author at the Department of Physics, Federal
Urdu University, Gulshan-e-Iqbal Campus Block 9, Karachi, Pakistan;
E-mail: [anonimizat] semiconducting, optical and piezoelectric properties
[3,8]. In particular, ZnO nanoparticles synthesized via chemical routes are found to be biologically compatible and environment friendly. Chemical synthesis usually involves ambient temperature thereby reducing the cost and complexity of the synthesis process. Many
chemical routes to synthesized ZnO have been
reported in literature such as sol–gel [9], thermal decomposition [10], micro emulsion [11] etc. However, all these methods either involve a number of unwanted chemicals or complex process steps. Thus the purity
and yield of the sample always remain an issue.
Here, we present a simple co-precipitation method
to synthesize uniform, spherically shaped and pure
ZnO nanoparticles using zinc acetate as a metal
precursor and dimethylformamide as a precipitating agent. No other dispersing or structure directing agents are used. X-ray diffraction shows that the synthesized ZnO nanoparticles have hexagonal crystal structure with an average crystallite size of 29 nm. Scanning
electron microscopy (SEM) reveals that the as
synthesized nanoparticles acquire uniform morphology. Energy dispersive x-ray spectroscopy (EDX) confirms that the synthesis process yields pure ZnO nanoparticles within its detection limit. UV–VIS absorption spectroscopy yield an absorption edge
value for ZnO nanoparticles in the wavelength ranges
of 300–400 nm. The band gap energy of the sample is found to be 3.50 eV, which is larger than the one

206 Journal of Basic & Applied Sciences, 2016, Volume 12 Shah et al.
reported for bulk samples (3.20 eV) [12]. The
antibacterial activity of ZnO nanoparticles is
systematically tested against gram positive (G+)
bacteria and gram negative (G-) bacteria by using agar-
well method. The results show that ZnO nanoparticles are strongly antimicrobial as they successfully suppressed the growth of a number of test
microorganisms.
EXPERIMENTAL DETAILS
The co-precipitation operations commonly contain
the substances like hydroxide, carbonates, sulphates,
acetates and oxalates [13]. In this particular research,
we adopt the co-precipitation method for the preparation of nanoparticles of ZnO of nearly uniform size [14]. Zinc acetate dehydrate and DMF were used for synthesizing ZnO nanoparticles and all chemical were purchased from Merck and are of analytical
grade. All the glassware were cleaned first with distilled
water and then with acetone and dry air. The desired amount of Zinc acetate dehydrate was weighted on an electronic balance and mixed with 200 ml of DMF in a round bottom flask. The mixture was stirring at room temperature for 30 minutes to make a homogeneous
mixture. Thereafter, the temperature of the flask was
raised to and kept stable at 200
oC for 3 hours on a hot
plate with continuous stirring. The mixture was then brought to room temperature (RT) and wash several time to remove unreacted product. After that the
obtained yield of the sample was centrifuged at 4000
rpm to separate the precipitates. The resulting sample
was dried at 70
oC in an oven for 24 hours and then
annealed at 400 oC for 10 hours.
RESULTS AND DISCUSSION
X-ray diffraction (XRD) was performed on ZnO
nanoparticles to determine the particle size and phase purity. We use a Bruker Axis, D8 Advance diffractometer with Cu K

radiation (
= 1.54 Å) at 40
kV. Figure 1 shows the XRD pattern of ZnO
nanoparticles. The XRD peaks are significantly broader
as compared to bulk samples [15]. Briefly, a peak in the diffraction pattern originates from the sum of the diffracted intensities over all atoms in the crystal [16]. Due to the large number of atoms in bulk crystals the sum generally converge resulting in a delta function or
a very narrow peak. Nanoparticles on the other hand
consists of small crystallites having finite number of atoms. Thus the diffracted intensity does not converge effectively and a rather broad peak results. The data obtained from X-rays diffractometer are further refined using Maud material analysis software. XRD pattern of
the sample has prominent peaks at 2 theta values of
31.73°, 34.37°, 36.21°, 47.47°, 56.55°, 62.77°, 66.31°, 67.87° and 69.01° corresponding to (100), (002), (101), (102), (110), (103), (200), (112) and (201) planes. The

Figure 1: XRD pattern of ZnO nanoparticles. Inset shows magnified view of (101) peak.

Synthesis and Characterization of Zinc Oxide Nanoparticles Journal of Basic & Applied Sciences, 2016, Volume 12 207
lattice constants of our sample are found to be a=b=
3.2530 Å and c = 5.2130 Å in good agreement with the
values of hexagonal ZnO of the space group P63mc.
The (hkI) values are also in good agreement with the
standard card of ZnO powder [17].
The average size of nanoparticles is found by using
Debye-Scherrer equation.
D=0.9/Cos 
where, ,  and  are the X-ray wavelength of (Cu-K
),
the full width at half maximum and the angle of (101) diffraction plane respectively. The crystallite size of the sample is found to be around 29 nm. The SEM image of ZnO nanoparticles is shown in Figure 2. A high
degree of agglomeration is clearly visible in agreement
with previous studies [18]. The observation of some
larger nanoparticles in SEM image is attributed to agglomeration [19]. EDX spectrum of ZnO nanoparticle samples is shown in Figure 3. The names and
percentages of the elements for the ZnO sample are shown in the labeling. Clearly, Zn and O are the main
constituents of the sample [20] and no trace of
impurities could be found within the detection limit of
EDX.

Figure 2: Morphology of Zinc Oxide Nanoparticles.

Figure 3: EDX Spectra of Zinc Oxide Nanoparticles. Optical properties of the samples were studied by
UV–VIS absorption spectroscopy. The absorption
spectra of sample were recorded in the range 300 nm
to 900 nm by a UV-2600 Spectrometer ( Shimadzue) .
We use DMF as the reference solution for the absorption spectrum of ZnO nanoparticles. Figure 4
shows the UV-VIS spectrum for ZnO nanoparticle. It should be noted that the absorption edge values for
ZnO samples lie in the wavelength ranges of 300 – 400
nm. The observed UV peak is found to be in good agreement with previously reported [21] free exciton transition peak. This transition is an intrinsic feature of the wurtzite ZnO and has its origin in the excitonic
recombination [22].
The type of electronic transition and band gap can
be determined with the help of optical absorption
spectrum. When the band gap ( Eg) of a semiconductor
is smaller than the photons of higher energy, an electron is transferred from the valence band to the conduction band. This causes an abrupt increase in the absorbency of the material to the wavelength corresponding to the band gap energy [23]. The
relation of the absorption coefficient (
), incident
photon energy
hv and Eg
is given by,
=(hv
Eg)1
2A
hv
where hv photon energy,
=4k/= absorption
coefficient ( k = absorption index or absorbance) and A 

constant. The value of Eg is found to be around 3.50
eV by the straight line portion of (
hv)2=0 axis; (see
Figure 5). The value of Eg is found to be larger than the
bulk value in agreement with Ref. [9]. A shift in the Eg
of ZnO nanoparticles from its bulk value of 3.20 eV is observed [24]. The increase in the Eg with decrease in
the crystallite size is due to finite size effects.

Figure 4: UV-VIS spectra of ZnO Nanoparticles.

208 Journal of Basic & Applied Sciences, 2016, Volume 12 Shah et al.

Figure 5: (
hv)2 vs. photon energy (h ) of ZnO
nanoparticles.
Furthermore, we have tested the antimicrobial
activity of our ZnO nanoparticles against thirteen G+
bacteria and twenty G- bacteria. Muller Hinton Agar and
Muller Hinton Broth were used as culturing media for bacterial strains according to the procedure described in Ref. [25]. ZnO nanoparticles were then tested for their antibacterial activity against thirteen G
+ bacteria
and twenty G- bacteria, by using Agar-well method.
Initially, the bacterial culture was refreshed using
autoclaved Muller Hinton broth. Thereafter, wells of suitable size and separation were punched into Muller Hinton Agar and 10 micro-liters of bacteria culture was carefully dispensed into the wells [26]. The plates were then allowed to incubate at 28
oC for 1 to two days after
which the incubation diameter of zone of inhibition (ZI)
was noted by Vernier caliper. Table 1 shows the
estimated values ZI for different bacteria. As a standard an antibiotic Gentamicin was used. It should be noted that out of 13 G
+ and 20 G- bacteria, ZnO nanoparticles
exhibit significant antibacterial features against 4 G+
and 6 G- bacteria. No antibacterial activity could be
noticed for the rest of the bacteria studied. For G+
bacteria, ZnO exhibits maximum activity (22±2) against Bacillus subtilis and minimum activity ((13±2) against
Bacillus cereus bacteria. On the other hand for G
–
bacteria, the maximum (20±1) and minimum (10±0)
activities were recorded for Enterobacter aerogenes
and E. coli , respectively.
Beside the size of inhibition zone, Minimum
inhibitory Concentration (MIC) of ZnO sample can also be used to quantify its antibacterial activity. MIC is the minimum concentration of antibacterial agent that stops visible growth of bacteria after overnight exposure. Clearly, a small value of MIC means strong antibacterial activity. In order to estimate the MIC of the
sample by Micro broth dilution method using 96-well
microtiter plate [27] the following steps were performed.
Step-1 : Solution-A of the nanoparticles was prepared in
ultra-pure distilled water for a range of concentrations 10 g/ml – 1 g/ml. Step-2 : Microbial inoculums were
prepared in microtiter plate by sub culturing microorganisms (at 37
0C for 2 hrs) into standard
Muller Hinton Broth (MHB) [28]. These were diluted to
approximately 105 to 106 of organisms/ml in MHB (Solution-B). Step-3 : A 100 μl of solution A (for each
dilution) is added to 100 μl of solution B (for each test
microorganism) in the microplate wells [29]. Step-4 :
These plates were incubated at 37
0C for one day.
Thereafter, 40 μL, 0.02 mg/ml triphenyl tetrazolium
chloride (TTC) were poured in each microplate well. This caused in a change of color of TTC from colorless to red due to microbial growth [30]. Step-5: Finally, the MIC of ZnO nanoparticles was determined as the lowest concentration that stopped the visible growth of the test microorganism.
The estimated values of MICs against different
bacteria mentioned Table 1, are presented in Table 2.
The antibacterial activity of ZnO nanoparticles were determined against thirteen G
+ bacteria ( Bacillus(B)
cereus, Bacillus(B) subtilis, Bacillus(B) thruingiensis,
Corynebacterium(C) diptheriae, Corynebacterium(C) hofmanii, Corynebacterium(C) xerosis, Staphylococcus
(S) epidermidis, Streptococcus(S) saprophyticus,
Staphylococcus(S) aureus, Staphylococcus(S) aureus AB 188, M. smegmatis, Streptococcus(S) fecalis,
Streptococcus(S) pyogenes ). The result showed that
only 4 grams positive bacteria were found active for ZnO nanoparticles as shown in Table 1. The twenty G
–
bacteria were screened ( Enterobacter(E) aerogenes,
Escherichia(E) coli ATCC 8739, Escherichia(E) coli, E.
coli multi drug resistance , Klebsiella (K) pneumonia,
Salmonella(S) typhi, Salmonella(S) paratyphi A, Salmonella(S) paratyphi B, Shigella(S) dysenteriae, Serratia(S) marcesens, Acinetobacter(A) baumii,
Campylobacter(C) jejuni, Campylobacter(C) coli,
Helicobactor(H) pylori, Hemophilus(H) influenza, Vibrio(V) cholera, Aeromonas(A) hydrophila, Proteus(P) mirabilis, Pseudomonas(P) aeruginosa and Pseudomonasaeroginosa ATCC). Among these gram
negative bacteria 6 bacteria were found active for the sample as shown in Table 2.
CONCLUSION
ZnO nanoparticles are synthesized and tested for
their antibacterial activity against thirteen grams

Synthesis and Characterization of Zinc Oxide Nanoparticles Journal of Basic & Applied Sciences, 2016, Volume 12 209
positive bacteria and twenty grams negative bacteria
by using agar-well method. These ZnO nanoparticles are synthesized by a simple co-precipitation method. X-ray diffraction confirms the formation of hexagonal ZnO nanoparticles with lattice constants a=b= 3.2530 Å and
c = 5.2130 Å. The average crystallite size of is found to
be 29 nm using Debye-Scherrer formula. Scanning electron microscopy (SEM) reveals that as synthesized nanoparticles are monodisperse. No trace of impurity could be detected by Energy dispersive x-ray spectroscopy (EDX). UV–VIS absorption spectroscopy
yield an absorption edge value in the wavelength
ranges of 300-400 nm and a band gap of 3.50 eV. The ZnO nanoparticles are found to exhibit strong antimicrobial features with quite low values of minimum
inhibitory concentrations (MIC) ~ 80 – 280
g/ml.
ACKNOWLEDGEMENT
The work at Nanoscale Condensed matter research
Laboratory (NCRL), Department of Physics Federal Urdu University, Karachi is partially supported by
FUUAST Dean research grant titled “ Mini-project 2016 ”
REFERENCES
[1] Applerot G, Lellouche J, Perkas N, Nitzan Y, Gedanken A,
Banin E. ZnO nanoparticle-coated surfaces inhibit bacterial biofilm formation and increase antibiotic susceptibility. RSC
Adv 2012; 2: 2314-2321.
http://dx.doi.org/10.1039/C2RA00602B
[2] Yu SF, Yuen C, Lau SP, Park WI, Yi GC. Random laser
action in ZnO nanorod arrays embedded in ZnO epilayers.
Appl Phys Lett 2004; 84: 3241-3243.
http://dx.doi.org/10.1063/1.1734681
[3] Peter KS, Rosalyn LK, George LM, Kenneth JK. Metal oxide
nanoparticles as bactericidal agents. Langmuir 2002; 18:
6679-6686.
http://dx.doi.org/10.1021/la0202374
[4] Premanathan M, Karthikeyan K, Jeyasubramanian K,
Manivannan G. Selective toxicity of ZnO nanoparticles toward Gram-positive bacteria and cancer cells by apoptosis
through lipid peroxidation. Nanomed Nanotechnol. Biol Med
2011; 7: 184-192.
http://dx.doi.org/10.1016/j.nano.2010.10.001

[5] Xie Y, He Y, Irwin PL, Jin T, Shi X. Antibacterial activity and
mechanism of action of zinc oxide nanoparticles against
Campylobacter jejuni. Appl Environ Microbiol 2011; 77: 2325-2331. http://dx.doi.org/10.1128/AEM.02149-10

[6] Huang Z, Zheng X, Yan D, Yin G, Liao X, Kang Y, Yao Y,
Huang D, Hao B. Toxicological effect of ZnO nanoparticles
based on bacteria. Langmuir 2008; 24: 4140-4144.
http://dx.doi.org/10.1021/la7035949
[7] Sawai J, Yoshikawa T. Quantitative evaluation of antifungal
activity of metallic oxide powders (MgO, CaO and ZnO) by an
indirect conductimetric assay. Journal of Applied Microbiology 2004; 96: 803-809. http://dx.doi.org/10.1111/j.1365-2672.2004.02234.x

[8] Huang MH, Mao S, Feick H, Yan H, Wu Y, Kind H, Weber E,
Russo R, Yang P. Room-temperature ultraviolet nanowire
nanolasers. Science 2001; 292(5523): 1897-1899.
http://dx.doi.org/10.1126/science.1060367
Table 1: Antibacterial Potential of ZnO Nanoparticles
Gram positive bacteria Zone of inhibition in mm
(mean ± S.D) Gram negative bacteria Zone of inhibition in mm
(mean ± S.D)
Bacillus cereus 13±2 Enterobacter aerogenes 20±1
Bacillus subtilis 22±2 Escherichia coli ATCC 8739 12±1
Bacillus thruingiensis 20±1 Escherichia coli 10±2
Staphylococcus epidermidis 15±1 E. coli multi drug resistance 10±0
– – Serratia marcesens 10±1
Acinetobacter baumanii 18±0

Table 2: Minimum Inhibitory Concentration of ZnO Nanoparticles
Gram positive bacteria Minimum inhibitory
concentration (
g/ml) Gram negative bacteria Minimum inhibitory
concentration (
g/ml)
Bacillus cereus 260 Enterobacter aerogenes 80
Bacillus subtilis 280 Escherichia coli ATCC 8739 100
Bacillus thruingiensis 140 Escherichia coli 180
Staphylococcus epidermidis 120 E. coli multi drug resistance 180
– – Serratia marcesens 120
– – Acinetobacter baumanii 180

210 Journal of Basic & Applied Sciences, 2016, Volume 12 Shah et al.
[9] Seema R, Poonam S, Shishodia, Mehra RM. Synthesis of
nanocrystalline ZnO powder via sol-gel route for dye-
sensitized solar cells. Solar Energy Materials & Solar Cells 2008; 92: 1639-1645. http://dx.doi.org/10.1016/j.solmat.2008.07.015

[10] Svetozar M, Ankica S, Stanko P. Formation of nanosize ZnO
particles by thermal decomposition of zinc acetylacetonate
monohydrate. Ceramics International 2010; 36(3): 1117-1123. http://dx.doi.org/10.1016/j.ceramint.2009.12.008

[11] Agrell J, Germani G, Jaras SG, Boutonnet M. Production of
hydrogen by partial oxidation of methanol over ZnO-supported palladium catalysts prepared by microemulsion
technique. Appl Catal A 2003; 242: 233-245.
http://dx.doi.org/10.1016/S0926-860X(02)00517-3

[12] Singh S, Chakrabarti P. Comparison of the structural and
optical properties of ZnO thin films deposited by three different methods for optoelectronic applications,
Superlattices Microstruct 2013; 64: 283-293.
http://dx.doi.org/10.1016/j.spmi.2013.09.031

[13] Noboru I, Ozaki Y, Kashu S, James M. Superfine particle
technology. New York: Springer Verlag; 1992. Available
from: http://link.springer.com/book/10.1007/978-1-4471-
1808-4
[14] Kumar S, Asokan K, Kumar SR, Chatterjee S, Kanjilal D,
Kumar GA. Investigations on structural and optical properties of ZnO and ZnO:Co nanoparticles under dense electronic
excitations. RSC Adv 2014; 4: 62123-62131.
http://dx.doi.org/10.1039/C4RA09937K

[15] Jian MZ, Yan Z, Ke-Wei X, Vincent J. General compliance
transformation relation and applications for anisotropic hexagonal metals. Solid State Communications 2006; 139:
87-91.
http://dx.doi.org/10.1016/j.ssc.2006.05.026

[16] Tam
s U. The Meaning of Size Obtained from Broadened X-
ray Diffraction Peaks. Advanced Engineering Materials 2003;
5: 323-329.
http://dx.doi.org/10.1002/adem.200310086
[17] Powder Diffraction File, Alphabetical Index, Inorganic
Compounds, Published by JCPDS International Centre for Diffraction Data, Newtown Square, PA. 19073, 2003 (JCPDS Card No.: 36-1451).
[18] Chou TP, Qifeng Z, Glen EF, Guozhong C. Hierarchically
Structured ZnO Film for Dye-Sensitized Solar Cells with Enhanced Energy Conversion Efficiency. Adv Mater 2007;
19: 2588-2592.
http://dx.doi.org/10.1002/adma.200602927

[19] Caglara M, Yakuphanoglub F. Structural and optical
properties of copper doped ZnO films derived by sol-gel. Applied Surface Science 2012; 258: 3039-3044. http://dx.doi.org/10.1016/j.apsusc.2011.11.033
[20] Rana SB, Singh P, Sharma AK, Carbonari AW, Dogra R.
Synthesis and characterization of pure and doped ZnO
nanoparticles. Journal of Optoelectronics and Advanced Materials 2010; 12: 257-261. https://www.ipen.br/biblioteca/
2010/16402.pdf
[21] Van Dijken A, Makkinje J, Meijerink A. The influence of
particle size on the luminescence quantum efficiency of
nanocrystalline ZnO particles. Journal of Luminescence.
2001; 92(4): 323-328.
http://dx.doi.org/10.1016/S0022-2313(00)00262-3

[22] Naeem M, Qaseem S, Gul I, Maqsood A. Study of active
surface defects in Ti doped ZnO nanoparticles. J Appl Phys
2010; 107: 124303.
http://dx.doi.org/10.1063/1.3432571
[23] Wang JF, Wen BS, Hong C, Wen XW, Guo Z. (Pr, Co, Nb)-
Doped SnO2 Varistor. J Am Ceram Soc 2005; 88: 331-334. http://dx.doi.org/10.1111/j.1551-2916.2005.00095.x

[24] Viswanatha R, Sapra S, Satpati B, Satyam PV, Dev BN,
Sarma DD. Understanding the quantum size effects in ZnO
nanocrystals. Journal of Materials Chemistry 2004; 14:661-668. http://dx.doi.org/10.1039/b310404d

[25] Talat M, Yasmeen B, Humera I, Iffat M, Aneela W, Sikandar
S. Complexation and Antimicrobial activities of  sitosterol
with trace metals. (Cu (II), Co (II), and Fe (III). European
Academic Research 2013; 1: 677-685. Available from:
http://euacademic.org/UploadArticle/100.pdf
[26] Perez C, Paul M, Bazerque P. An antibiotic assay by the
agar well diffusion method. Acta Biol Med Exp 2009; 15: 113-
115.
[27] Julia AK, George EH, Max S, Wendy A, Catherine M, Cynthia
C. Use of the National Committee for Clinical Laboratory
Standards Guidelines for Disk Diffusion Susceptibility Testing
in New York State Laboratories. J Clin Microbiol 2000; 38(9): 3341-3348. Available from: http://www.ncbi.nlm.nih.gov/pmc/ articles/PMC87384/
[28] Olson CR, Balasubramaniam T, Shrum J, Nord T, Taylor PL,
Burrell RE. Novel Antimicrobial Activity of Nanocrystalline Silver Dressings. Int. Congress on MEMS 2005; 129-131. http://dx.doi.org/10.1109/ICMENS.2005.90

[29] Sougata S, Atish DJ, Samir KS, Golam M. Facile synthesis of
silver nano particles with highly efficient anti-microbial
property. J Polyhedron 2007; 26: 4419-4426.
http://dx.doi.org/10.1016/j.poly.2007.05.056
[30] Navarro V, Villarreal ML, Rojas G, Lozoya X. Antimicrobial
evaluation of some plants used in Mexican traditional
medicine for the treatment of infectious diseases. J Ethnopharmacol 1996; 53(3): 143-147. http://dx.doi.org/10.1016/0378-8741(96)01429-8

Received on 21-03-2016 Accepted on 12-04-2016 Published on 29-04-2016

http://dx.doi.org/10.6000/1927-5129.2016.12.31

© 2016 Shah et al.; Licensee Lifescience Global.
This is an open access article licensed under the terms of the Creative Commons Attribution Non-Commercial License
(http://creativecommons.org/licenses/by-nc/3.0/ ) which permits unrestricted, non-commercial use, distribution and reproduction in
any medium, provided the work is properly cited.