Antibacterial Activity of Silver and Gold Particles Formed on Titania Thin Films (original) (raw)
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Nanomaterials
Multiple antibiotic resistance has now become a major obstacle to the treatment of infectious diseases. In this context, the application of nanotechnology in medicine is a promising alternative for the prevention of infections with multidrug-resistant germs. The use of silver as a powerful antibacterial agent has attracted much interest. TiO2 and SiO2 thin films enhanced with Ag particles have been developed with the aim of maintaining the transparency of the polymer films. Antibacterial activity was evaluated for a Gram-negative species-Escherichia coli-in concentrations of 105 and 104 CFU/mL in different conditions-activation by UV irradiation, single layer and double layer. Increased antibacterial efficacy of TiO2-deposited foil was found for the tests that had been exposed to UV activation. In the case of bilayer tests, the efficiency was higher compared to those in a single layer, as the contact surface between the films and the bacterial suspension increased. Films can be used...
Structural analysis of TiO2 and TiO2-Ag thin films and their antibacterial behaviors
Journal of Physics: Conference Series, 2012
TiO2 (rutile and anatase) thin films was first prepared using reactive sputtering, in an Ar+O2 plasma. In the 2nd stage of the experiment, various amounts (3, 7, and 10 at. %) of Ag was doped into the rutile film in order to form TiO2-Ag thin films. These films were annealed for one hour in Ar atmosphere, at 300, 400, and 500 °C. The films' structures were then examined using X-ray diffractometry. FESEM (field-emission scaning electron microscopy) was used to investigate the surface emergence of Ag particles. As for the examination of optical band gaps and absorption of these films, UV-Vis-NIR photometer was used. The results show that, in as-deposited condition, the addition of Ag might disrupt the growth of crystalline structure and cause the formation of amorphous films. After annealing, it is found that the structure tends to become anatase phase which is a metastable phase between amorphous titanium oxide and rutile. More importantly, the absorption of the Ag-doped films wo...
BioDiscovery
This research aims to study the antibacterial activity of thin films nanostructured TiO doped with Ag and Cu on Gracilicutes and Firmicutes bacteria with clinical significance. The thin films were deposited on glass substrates without heating during the deposition by radio frequency magnetron co-sputtering of TiO target and pieces of Ag and Cu. The total surface area of Ag was 60 mm and this one of Cu was 100 mm. The r.f. power was 50W and sputtering atmosphere was Ar (0,8 Pa). The thickness of the films was about 60 nm. The experiment was conducted under day light regime. The test strains Bacillus cereus, Staphylococcus epidermidis, Salmonella enterica, Escherichia coli and Pseudomonas sp. were used. The bactericidal effect was established at different time point between 30 min-90 min for Pseudomonas sp. and S. enterica. The Firmicutes bacteria B. cereus and S. epidermidis were killed at 4 and 8 h of the treatment respectively. The effect against E.coli was bacteriostatic till 10 hour. The toxic effect was evaluated by classical Koch's method and optical density measurments. The results were confirmed by assessment of dehydrogenase activity inhibition. The film could be used in medical and clinical practice.
CVD Elaboration of Nanostructured TiO 2 -Ag Thin Films with Efficient Antibacterial Properties
Chemical Vapor Deposition, 2010
Nanostructured TiO 2 -Ag composite coatings are deposited by direct liquid injection metal-organic (DLI-MO) CVD at 683 K in a one-step process. Silver pivalate (AgPiv) and titanium tetra-iso-propoxide (TTIP) are used as Ag and Ti molecular precursors, respectively. Metallic silver nanoparticles are co-deposited with anatase TiO 2 on stainless steel, glass, and silicon wafers. The silver particles are uniformly embedded in the oxide matrix through the entire film thickness. The influence of the growth conditions, including injection parameters, is investigated on the chemical, physical, and structural characteristics of the coatings as well as on their anti-bacterial activities. The bacterium Staphylococcus aureus is employed for anti-bacterial tests. The films are bactericidal, according to the JIS Z 2801 standard test performed in the dark, when they contain less than 1 at.-% of silver. Under UV irradiation they exhibit a photocatalytic activity which decays by increasing the silver content. As a result of this dual functionality, the TiO 2 -Ag nanocomposite coatings show promising potentialities as long-term anti-bacterial surfaces since selfcleaning can be achieved periodically under UV light in order to maintain an efficient anti-bacterial activity in the dark or in visible light.
Synthesis of Ag–TiO2composite nano thin film for antimicrobial application
Nanotechnology, 2011
TiO 2 photocatalysts have been found to kill cancer cells, bacteria and viruses under mild UV illumination, which offers numerous potential applications. On the other hand, Ag has long been proved as a good antibacterial material as well. The advantage of Ag-TiO 2 nanocomposite is to expand the nanomaterial's antibacterial function to a broader range of working conditions. In this study neat TiO 2 and Ag-TiO 2 composite nanofilms were successfully prepared on silicon wafer via the sol-gel method by the spin-coating technique. The as-prepared composite Ag-TiO 2 and TiO 2 films with different silver content were characterized by scanning electron microscopy (SEM), atomic force microscopy (AFM), x-ray diffraction (XRD) and x-ray photoelectron spectroscopy (XPS) to determine the topologies, microstructures and chemical compositions, respectively. It was found that the silver nanoparticles were uniformly distributed and strongly attached to the mesoporous TiO 2 matrix. The morphology of the composite film could be controlled by simply tuning the molar ratio of the silver nitrate aqueous solution. XPS results confirmed that the Ag was in the Ag 0 state. The antimicrobial effect of the synthesized nanofilms was carried out against gram-negative bacteria (Escherichia coli ATCC 29425) by using an 8 W UV lamp with a constant relative intensity of 0.6 mW cm −2 and in the dark respectively. The synthesized Ag-TiO 2 thin films showed enhanced bactericidal activities compared to the neat TiO 2 nanofilm both in the dark and under UV illumination.
This article aims to explore the antibacterial activity of thin films of TiO doped with Ag and Cu using two types of Gram-negative and Gram-positive test bacteria with clinical significance (Gracilicutes and Firmcutes bacteria). The thin films (thickness of about 60 nm) were deposited on glass substrates by radio frequency magnetron co-sputtering (r.f. power of 50 W) of TiO target with Ag and Cu pieces on its surface in an Ar atmosphere (0.8 Pa) without heating during the deposition. The total surface area of the Ag was 60 mm and that of the Cu was 100 mm . Bacillus cereus, Staphylococcus epidermidis, Salmonella enterica, Escherichia coli and Pseudomonas sp. were used as test strains. The antibacterial actvity of the films was evaluated by the classical Koch's method and optical density measurements. The bactericidal effect was established at different time points between 30 min and 90 min for Pseudomonas sp. and S. enterica. The Firmicutes bacteria B. cereus and S. epidermidis were killed at the 4 and 8 hour of the treatment, respectively. The effect on E. coli was bacteriostatic until the 10 hour. The results were confirmed by assessment of the bacterial dehydrogenase activity. The studied thin films of TiO co-doped with Ag and Cu have a potential for application as antibacterial coatings.
2014
In this research, undoped and doped (Fe, Ce, and Ag) antibacterial coatings of nanostructured TiO2 films were prepared by a sol-gel dip coating method. Doped and undoped TiO2 films were excited with ultraviolet (UV) radiation to improve their photo catalytic activity. The antibacterial activity against Staphylococcus Aureus bacteria was studied using an antibacterial–drop test and colony count method. The Fe doped TiO2 films exhibited higher antibacterial activity than other samples. The percent of bacteria killing or killed (PBK) on bare glass substrate, undoped, Ce, Ag, and Fe doped TiO2 thin films (after UV illumination) were 23.8, 50.3, 57.8, and 70.1%, respectively. Uv-Visible Spectrophotometry, Photoluminescence (PL), X-ray Diffraction (XRD), and Atomic Force Microscopy (AFM) were carried out to study the relation between optical, luminescence, structural, and surface morphological characteristics of the samples with their antibacterial activities. Several parameters such as t...
Malaysian Journal of Microbiology, 2012
Aim: Nanotechnology is an increasingly growing field with its current application in Science and Technology for the purpose of manufacture of novel materials at the nanoscale level. Silver-Titania nanoparticles (AgTiO2-NPs) have been known to have inhibitory and bactericidal effects. Methodology and Results: In the present study, stable silver-titania nanoparticles coated metallic blocks were prepared for testing their efficacy against selected bacterial pathogens like Escherichia coli and Staphylococcus aureus. In the experimental part, the bacterial pathogens were inoculated on silver-titania nanoparticle coated blocks and the treatment was carried out in "0" time and "24" h interval and were enumerated. Conclusion, significance and impact of study:The results were compared with the control (uncoated metallic blocks) and analyzed by using Japanese Industrial Standard (JIS Z2801:2000) method. From this study, it was concluded that silver-titania nanoparticles has inhibitory effect on bacterial pathogen tested.
Role of silver nanoparticles in imparting antimicrobial activity of titanium dioxide
Materials Letters, 2016
In the present work, facile syntheses for titanium dioxide (TiO 2), Silver (Ag), and Ag/TiO 2 nanoparticles were applied through sol-gel technique. Structural and morphological characterizations were followed by UV, TEM, and SAED. The cup agar diffusion method was followed to investigate the bactericidal activities against three common bacterial strains being Escherichia coli (Gram-negative), Bacillus subtitles and Staphylococcus aureus (Gram positive). The bactericidal activities were evidenced by the inhibition zones of the bacterial growth around the resultant substrates. The results prove promising bactericidal activity of Ag and Ag/TiO 2 nanophases compared to TiO 2 anatase phase nanoparticles possessing no bactericidal activity. The combined presence of silver nanoparticles along with the anatase phase induced a promising bactericidal activity.
Comparative Study of Antibacterial Efficiency of M-TiO2 (M = Ag, Cu) Thin Films Grown by CVD
Key Engineering Materials, 2014
M-TiO2 (M = Ag, Cu) nanocomposite layers were grown by pulsed direct liquid injection chemical vapor deposition (DLICVD) on various substrates to produce bactericidal surfaces with long term activity. Monodisperse Ag nanoparticles (NPs) with an average size of 5-10 nm are embedded in an anatase matrix. A bactericidal behavior determined by the JIS Z 2801 standard test was found for Ag-TiO2 films for Ag ≤ 1 at. % and above. Higher Ag content is not necessary since efficiency is already at its maximum (relative activity 100%). By contrast, using Cu as antibacterial agent, a larger size distribution of metal particles was found (20 to 400 nm). Cu-TiO2 films exhibit a bactericidal behavior if their thickness is higher than 100 nm and Cu content ≥ 3.5 at. %. These coatings are still antibacterial after 5 months of aging and their efficiency has decreased by only 35%.