World Journal Of Engineering
The antibacterial activities of Ag doped T-ZnO
Xing Duan, Xiaoling Xu, Zuowan Zhou1
Key Laboratory of Advanced Technologies of Materials (Ministry of Education), School of Materials Science and
Engineering, Southwest Jiaotong University, Chengdu, 610031, P. R. China
broth in flasks. Subsequently, 200 μl bacterial culture
(108 cfu ml−1) was inoculated into the above sterilized
Introduction
LB broth containing the materials and incubated at 37
The strong antibacterial activities of metallic Ag and
◦C on a rotary shaker for 18 h in the dark room (shaking
Ag+ ions have been known for a long time[1-4],
provided the bacteria with aeration and homogeneity).
however, Ag is so expensive that cannot be directly
Finally, aliquots of the treated cells were diluted
used in many fields .Therefore, there is necessary to
appropriately with LB medium, and then the dilutions
find low-cost methods of using silver. So, Ag
were spread on agar plates and incubated overnight at
nanoparticles have been suppoeted on SiO2[5],
37 ◦C to count the clones and calculate the amount of
zeolites[6], carbon fibers[7], and etc.. These ways are
active cells. The counts on the three plates were
inert of antibacterial activity. ZnO is anther inorganic
averaged. The lowest concentration which needed to
antibacterial agent and relatively low-cost, it can be
inhibit the growth of bacteria was defined as the MIC.
used as an excellent support for Ag nanoparticles. the
Results and discussion
Ag/T-ZnO showed good antibacterial activities for both
gram-negative and gram-positive bacteria [8]. In the
present work, we report a simple method to get
Ag/T-ZnO, which has positive antibacterial activities.
Experimental
Materials
The T-ZnO had been reported in our former research
[9]. Ag/T-ZnO compound was prepared by the solid
solutions method in which T-ZnO and Ag2CO3 were
used. The fabrication processes were as follows: a
certain amout Ag2CO3 and T-ZnO were mixed envnly
then got into 850 ℃ muffle furnace for 1 h.
Characterizations and Antibacteria activities
The structure of samples was investigated by X-ray
diffraction (XRD, Rigaku Dymax) with a Cu target and
a monochronmator at 50 kV and 300 mA. Scanning
electron microscope (SEM, Camscan-4) with a working
voltage of 20 kV was used to characterize the surface
morphology of the Ag/T-ZnO compound. The
antibacterial activities were evaluated by minimal
inhibitory concentration (MIC) method. In a typical
procedure, the Ag/T-ZnO were suspended in 10 ml
distilled water with different concentrations and
oscillation dispersion, then suspended in 10 ml LB
1
Figure 1 XRD patterns of pure T-ZnO and Ag/T-ZnO
nanocomposites with different Ag contents.
Fig.1 shows the X-ray diffraction patterns of the T-ZnO
and Ag/T-ZnO composites with the different Ag/T-ZnO
weight ratios ranging from 0.5 to 2%. It can be seen
that the diffraction peaks at 2θ=31.88°, 34.41°, 36.26°
and 47.52° are attributed to the typical wurtzite
structure of ZnO, and diffraction peak at 2θ=38.1° is
assigned to metal Ag. This indicates that wurtzite ZnO
and fcc Ag phases coexist in the Ag/ ZnOw composites.
The intensity of the peaks of Ag increases with the
increase of Ag content.
Fig. 2 (a)-(e) show the SEM images of T-ZnO and
Ag/T-ZnO with different weight rations of Ag Fig.2(a),
(b) give that the arm of Ag/T-ZnO has no evident
stacking particles. It can be seen from Fig. 2 (c) to
Fig.2(f) that the Ag particles is increased with the
Author to whom correspondence should be addressed, E-mail: zwzhou@at-c.net
287
World Journal Of Engineering
increasing of doping amount of Ag. The size of Ag
particle is about 10~50nm..
(a)
(b)
(c)
(d)
(e)
(f)
Figure 2 SEM images of (a) T-ZnO
One reason is that T-ZnO, as a support, decreases the
aggregation of Ag nanopaticles, and accordingly the Ag
nanoparticles can have more opportunities to attach to
the cell membranes and interact with sulfur- and
phosphorus-containing compounds in them. Zinc oxide
itself have good antibacterial properties, T-ZnO has
better antibacterial activity than p-ZnO and n-ZnO in
our present work[10]. The interaction between the Ag
nanoparticles and the cell membrane will disturb power
functions of the cell, such as permeability and
respiration, finally resulting in cell death.
Conclusion
Ag/T-ZnO with different
Ag/T-ZnO composites were successfully synthesized by
solid solutions method .The antibacterial activities were
enhanced by the dopping of Ag on T-ZnO. It will be a
good method for sufficiently exerting the good
antibacterial effect of Ag and T-ZnO.
References
weight ratios of (b) 0wt% (c)0.5wt% (d) 1.0wt% (e )1.5wt%
(f )2.0wt%
Table 1. Minimum inhibition concentrations (MIC) values of
ZnO and Ag/T-ZnO samples against E. coli in dark
Antibacterial agent
MIC(ppm)
T-ZnO
500
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