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Abstract(Please copy/paste the abstract send to the congress) : |
Characterization of silver doped ceramic tiles and its antibacterial activity
Nafiseh Baheiraeia, *, Fathollah Moztarzadehb, Mehdi Hedayatic
a school of advanced medical technologies, Tehran university of medical sciences,Tehran,Iran.email:nbaheiraei@gmail.com
*corresponding author
bFaculty of Biomedical Engineering, Amirkabir University of Technology,Tehran, Iran.email: moztarzadeh@aut.ac.ir,
c Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran.email: hedayati47@yahoo.com
Introduction: Ceramic tiles which are commonly used in any home or environment do not have antibacterial activity and microorganisms easily grow on their surfaces especially in moist environments. Silver-doped ceramics and glasses tend to be chemically durable, releasing silver ions for a long time, thus having a good antibacterial activity [1].This study aimed to examine the preparation and antibacterial activity of silver-doped silica thin film on glazed tiles by sol-gel method.
Materials and methods: Silver-doped coating films were prepared by sol-gel method. The starting solution was made from tetraethylorthosilicate, distilled water, nitric acid, ethanol and silver nitrate as a precursor for silver. coating was applied on ultrasonically cleaned glazed ceramic tiles using dip-coating technique. All films were dried at 100°C for an hour and thermal treatment was done in the air at 1100°C for two hours. The Ag/SiO2 thin films were investigated by Fourier Transform Infrared Spectroscopy , Scanning Electron Microscopy, X-ray Diffraction (XRD) and Wavelength Dispersive Spectrometry (WDS). Atomic Absorption Spectroscopy (AAS) was used for the quantitative determination of the silver ion concentration being released from films over a 24 day period. The antibacterial effects of Ag/SiO2 thin films against Escherichia coli and Staphylococcus aureus were also examined. S.aureus and E.coli were chosen as they are among the most prevalent species of gram-positive and gram-negative bacteria causing infection, respectively.
Results and discussion: Analysis results showed the presence of Ag elements on the surface of the coated tiles. Thermal treatment at high temperatures caused sharp XRD peaks and high crystallinity in this system. Good adhesion of the coating to the substrate was noticed by cross sectional images. Ag+ ions were released constantly and the mean release rate(±SD) was 0.104 ±0.01 µg/ml during 24 days. This indicates that silver ions are released from the surface of Ag/SiO2 thin films and these ions could kill microorganisms. Coating films exhibited an excellent antibacterial performance against both bacterium.
Conclusion: According to previous researches, high-temperature processing of silver-doped tetraethoxysilane films (>300 °C) results in the diffusion of Ag+ ions from the surface into the bulk [2] and silver valence might also be affected by thermal treatment at high temperature to reduce the antibacterial effect [3]. However, in our study the presence of Ag elements on the surface of the tiles was proved by WDS.Silver ions following the applied high temperature treatment(1100°C) released constantly as was proved by ASS data and these ions concentration are probably enough to inhibit the development of E.coli and S.aureus.It could be concluded that as-prepared coated glazed tiles have the antibacterial potential to decrease air pollution and improve hygiene.
Refrences:
[1] T. Toshikazu, Antimicrobial agent composed of silica-gel with silver complex, Inorg. Mater. 6 (1999) 505-511.
[2] W. Li, S. Seal, E. Megan, J. Ramsdell, K. Scammon, G. Lelong, L. Laurent, K.A. Richardson, Physical and optical properties of sol–gel nano-silver doped silica film on glass substrate as a function of heat-treatment temperature, J. Appl. Phys. 93 (2003) 9553–9561.
[3] H. Liu, Q. Chen, L. Song, R. Ye, J. Lu, H. Li, Ag-doped antibacterial porous materials with slow release of silver ions, J. Non-Cryst Solids. 354 (2008) 1314–1317. |