scholarly journals Enhanced Antibacterial Activity of Silver Doped Titanium Dioxide-Chitosan Composites under Visible Light

Materials ◽  
2018 ◽  
Vol 11 (8) ◽  
pp. 1403 ◽  
Author(s):  
Jie Li ◽  
Bing Xie ◽  
Kai Xia ◽  
Yingchun Li ◽  
Jing Han ◽  
...  
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Titanium Dioxide ◽  
Visible Light ◽  
Silver Ions ◽  
Antibacterial Activities ◽  
Nano Tio2 ◽  
Inverse Emulsion ◽  
Potential Applications

Nano titanium dioxide (TiO2) with photocatalytic activity was firstly modified by diethanolamine, and it was then doped with broad spectrum antibacterial silver (Ag) by in situ method. Further, both Ag doped TiO2-chitosan (STC) and TiO2-chitosan (TC) composites were prepared by the inverse emulsion cross-linking reaction. The antibacterial activities of STC composites were studied and their antibacterial mechanisms under visible light were investigated. The results show that in situ doping and inverse emulsion method led to good dispersion of Ag and TiO2 nanoparticles on the cross-linked chitosan microsphere. The STC with regular particle size of 1–10 μm exhibited excellent antibacterial activity against E. coli, P. aeruginosa and S. aureus under visible light. It is believed that STC with particle size of 1–10 μm has large specific surface area to contact with bacterial cell wall. The increased antibacterial activity was attributed to the enhancement of both electron-hole separations at the surface of nano-TiO2 by the silver ions under the visible light, and the synergetic and sustained release of strong oxidizing hydroxyl radicals of nano-TiO2, together with silver ions against bacteria. Thus, STC composites have great potential applications as antibacterial agents in the water treatment field.

scholarly journals Retrieval of effective aerosol diameter from satellite observations

2016 ◽  
Author(s):  
Humaid Al Badi ◽  
John Boland ◽  
David Bruce
Keyword(s):  
Particle Size ◽  
Energy System ◽  
Dust Storms ◽  
Aircraft Measurements ◽  
Infrared Band ◽  
Brightness Temperatures ◽  
Aerosol Particle Size ◽  
Potential Applications ◽  
Modelling And Forecasting

Abstract. Dust aerosol particle size plays a crucial role in determining dust cycle in the atmosphere and the extent of its impact on the other atmospheric parameters. The in-situ measurements of dust particle size are very costly, spatially sparse and time-consuming. This paper presents an algorithm to retrieve effective dust diameter using infrared band brightness temperature from SEVIRI (the Spinning Enhanced Visible and InfaRed Imager) on the Meteosat satellite. An empirical model was constructed that directly relates differences in brightness temperatures of 8.7, 10.8 and 12.0 μm bands to effective dust diameter using the Mie extinction efficiency factor. Three case studies are used to test the model. The results showed consistency between the model and in-situ aircraft measurements. A severe dust storm over the Middle-East is presented to demonstrate the use of the model. This algorithm is expected to contribute to filling the gap created by the discrepancies between the current size distributions retrieval techniques and aircraft measurements. Potential applications include enhancing the accuracy of atmospheric modelling and forecasting horizontal visibility and solar energy system performance over regions affected by dust storms.

Stability of nano-sized titanium dioxide in an aqueous environment: effects of pH, dissolved organic matter and divalent cations

2013 ◽  
Vol 68 (2) ◽  
pp. 276-282 ◽  
Author(s):  
X. N. Yang ◽  
F. Y. Cui
Keyword(s):  
Particle Size ◽  
Titanium Dioxide ◽  
Organic Matter ◽  
Zeta Potential ◽  
Dissolved Organic Matter ◽  
Ph Value ◽  
Divalent Cations ◽  
Aqueous Environment ◽  
Nano Tio2 ◽  
The Stability

Nano-sized titanium dioxide in the aquatic environment has a potential impact on the environment and human health. In this study, the impact of pH value, dissolved organic matter (DOM) and divalent cations (Ca2+) on the stability of titanium dioxide nanoparticles (nano-TiO2) in an aqueous environment was investigated in batch tests. The results showed that the particle size of nano-TiO2 was not sensitive to pH value but was inversely proportional to zeta potential. The nano-TiO2 becomes more stable with surface zeta potential, accompanied by small particle size and high dispersion. In the presence of DOM, the particle size was smaller and the stability of nano-TiO2 could be enhanced. This might be a synergistic effect of the ligand exchange and electrostatic force. Particle size increased with the addition of Ca2+ and the stability decreased.

scholarly journals Surface functionality density regulated in situ reduction of nanosilver on hierarchial wrinkled mesoporous silica nanoparticles and their antibacterial activity

RSC Advances ◽  
2018 ◽  
Vol 8 (35) ◽  
pp. 19420-19425 ◽  
Author(s):  
Xuejuan Wan ◽  
Lisi Wu ◽  
Hang Pei ◽  
Haoqi Ke ◽  
Guanghui Yang ◽  
...  
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Mesoporous Silica ◽  
Silica Nanoparticles ◽  
Mesoporous Silica Nanoparticles ◽  
Antibacterial Properties ◽  
In Situ Reduction ◽  
Surface Functionality

Nanosilver with diverse particle size was attached onto hierarchical WMS, and the resulted samples showed excellent antibacterial properties.

Preparation and Antibacterial Activity of Silver Ions-Substituted Hydroxyapatite/Titania

2006 ◽  
Vol 510-511 ◽  
pp. 78-81 ◽  
Author(s):  
Guo Yu Lv ◽  
Yu Bao Li ◽  
Ai Ping Yang ◽  
Xiang Zhang ◽  
Wei Hu Yang ◽  
...  
Keyword(s):  
Antibacterial Activity ◽  
Composite Materials ◽  
Silver Ions ◽  
Antibacterial Activities ◽  
Bacterial Strains ◽  
X Ray Diffraction ◽  
Disk Diffusion Test ◽  
Transmission Electron ◽  
Dose Dependent ◽  
Better Than

In this paper a series of silver ions-substituted hydroxyapatites (HA) were prepared. The antibacterial activities of these materials on textiles against bacteria have been investigated. Titania (TiO2) was selectively added into the materials to decrease the silver-ions concentration to get the same active antimicrobial effects. The microstructure, the shape and size, concentration of silver, and the groups of the composite materials were characterized using transmission electron microscopy (TEM), infrared spectroscopy (IR), Atomic absorption spectroscopy (AAS), and X-ray diffraction (XRD). The results showed that there was a dose dependent-effect of silver-ions concentration from the disk diffusion test. The higher the silver-ions concentration, the better the antibacterial activity of the composite materials was. Keeping silver-ions concentration constant, the antibacterial activity of the materials for adding Titania was better than that of without Titania. Moreover, the addition of Titania would inhibit the discolouration of the composite materials. The antibacterial activities of the composite materials differentiate to some extent with the bacterial strains.

Photocatalytic Activity of TiO2-C Composites under the Visible Light

2009 ◽  
Vol 610-613 ◽  
pp. 310-315
Author(s):  
Jin Huo Li ◽  
De Gui Zhu ◽  
Zong Yue Xue ◽  
Shuang Quan Guo
Keyword(s):  
Photocatalytic Activity ◽  
Methyl Orange ◽  
Visible Light ◽  
High Photocatalytic Activity ◽  
Ultraviolet Region ◽  
Gravimetric Analysis ◽  
Scanning Calorimetry ◽  
Nano Tio2 ◽  
Light Region

TiO2-C composites of high photocatalytic activity were in-situ fabricated with nano-TiO2 powders and resins. The composites were characterized by differential scanning calorimetry and thermal gravimetric analysis (DSC-TG), X-ray diffraction (XRD), UV-Vis diffuse reflection spectrum (DRS), transmission electron microscope (TEM) and scan electronic microscopy (SEM). XRD results indicated that the composites consist of carbon and anatase phases. UV-Vis DRS showed that composites not only have a good performance in the ultraviolet region, but also have a very good performance in the visible light region. Photocatalysis degradations of methyl orange with purity nano-TiO2 and TiO2-C composite were tested by lighting of visible light. After methyl orange liquid was lighted by visible light for 1 hour, the decolorization ratio of methyl orange can be up to 96.3%( reactive brilliant red X-3B:98.7%) with TiO2-C powders, while it was only 34.7% (reactive brilliant red X-3B:66.9%) with purity nano-TiO2 powders. In-situ fabricated carbon can change the width of energy band of TiO2 and adsorb methyl orange and reactive brilliant red X-3B molecules. The former accelerate the absorption of visible light, and the later raise the decomposition rate of methyl orange and reactive brilliant red X-3B. All of these can improve photocatalytic activity of TiO2-C composites under the visible light.

Antibacterial potential of essential oils of Zataria multiflora and Mentha piperita, micro- and nano-formulated forms

2020 ◽  
Author(s):  
Mahmoud Osanloo ◽  
Abbas Abdollahi ◽  
Alireza Valizadeh ◽  
Niloufar Abedinpour
Keyword(s):  
Particle Size ◽  
Antibacterial Activity ◽  
Essential Oils ◽  
Pathogenic Bacteria ◽  
Antibacterial Activities ◽  
Mentha Piperita ◽  
Zataria Multiflora ◽  
Microdilution Method ◽  
Better Than ◽  
Antibacterial Potential

Background and Objectives: Plant-derived essential oils (EOs) shave many usages in health and medicine, such as anti- bacterial agents. The aim of this study was the improvement of antibacterial activities of two EOs using nanotechnology. Materials and Methods: Antibacterial activity was investigated on four important human pathogenic bacteria using the 96-well plate microdilution method, a quantitative approach. Eleven formulations were prepared using each of the EOs. Eventually, the best nanoformulation with the smallest particle size and polydispersive indices (PDI and SPAN) was selected using each EO for further investigations. Moreover, two microemulsions with similar ingredients and the same portion in comparison with two selected nanoemulsions were also prepared. Antibacterial activity of each EO was compared with its micro- and nano-emulsions. Results: The antibacterial efficacy of Zataria multiflora EO (ZMEO) was significantly better than Mentha piperita EO (MPEO). Besides, the antibacterial activity of nanoemulsion of ZMEO with a particle size of 129 ± 12 nm was significantly better than no- and micro-formulated forms of ZMEO. Interestingly, the efficiency of MPEO nanoemulsion (160 ± 25 nm) was also significantly better than MPEO and its micro-formulated form. Conclusion: Regardless of the intrinsic antibacterial property of two examined EOs, by formulating to nanoemulsion, their efficiencies were improved. Nanoemulsion of ZMEO introduced as an inexpensive, potent and green antibacterial agent.

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