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Gao J.,CAS Shanghai Institute of Ceramics | Li C.,China Astronaut Researching and Training Center | Zhou J.,University of South Australia | Lu L.,CAS Shanghai Institute of Ceramics | And 2 more authors.
RSC Advances | Year: 2015

Alumina coatings have wide-ranging applications by virtue of their inherent wear and corrosion resistance and attractive dielectric and diffusion barrier properties. In many cases, they do not meet the antibacterial demand to eliminate microbiologically-induced corrosion and diseases. The aim of this work is to prepare plasma sprayed alumina-nanosilver (Al2O3/Ag) coatings and investigate their antibacterial properties with various compositions. Moreover, Al2O3/Ag coatings are optimized to use minimum amounts of silver nanoparticles (AgNPs) and exhibit excellent antibacterial properties. Al2O3 coatings with five different amounts of AgNPs were deposited on titanium alloys substrates by plasma spray. The Al2O3/Ag coatings, which were denoted as A1, A2, A3, A4 and A5, were prepared by using α-Al2O3 powders containing 1 ppm, 10 ppm, 100 ppm, 1000 ppm and 10000 ppm AgNPs, respectively. The composition and morphology of Al2O3/Ag coatings were investigated by X-ray diffraction and scanning electron microscopy. The antibacterial activity of Al2O3/Ag coatings was tested using Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) as model strains of Gram negative and Gram positive bacteria, respectively. The bacterial adhesion was also examined by employing both of the bacteria to observe bacterial adhesion status and evaluate antibacterial property of as-prepared coatings. The results showed the Al2O3/Ag coatings with more than 10 ppm AgNPs exhibited strong antibacterial property against E. coli and S. aureus. Bacterial adhesion assays showed that A2-A5 had anti-adhesive property of E. coli and S. aureus, which was in accordance with the antibacterial results. Moreover, the main factors influencing the antibacterial properties of Al2O3/Ag coatings were discussed with silver nanoparticles and hydrophobicity of the coatings. This journal is © The Royal Society of Chemistry 2015. Source


Gao J.,CAS Shanghai Institute of Ceramics | Zhao C.,China Astronaut Researching and Training Center | Zhou J.,University of South Australia | Li C.,China Astronaut Researching and Training Center | And 3 more authors.
Applied Surface Science | Year: 2015

Rutile titania (TiO2) coatings have superior mechanical properties and excellent stability that make them preferential candidates for various applications. In order to prevent infection arising from bacteria, significant efforts have been focused on antibacterial TiO2 coatings. In the study, titania-nanosilver (TiO2/Ag) coatings with five different kinds of weight percentages of silver nanoparticles (AgNPs) were prepared by plasma spray. The feedstock powders, which had a composition of rutile TiO2 powders containing 1-10,000 ppm AgNPs, were double sintered and deposited on stainless steel substrates with optimized spraying parameters. X-Ray diffraction and scanning electron microscopy were used to analysize the phase composition and surface morphology of TiO2/Ag powders and coatings. Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus) were employed to examine the antibacterial activity of the as-prepared coatings by bacterial counting method. The results showed that silver existed homogeneously in the TiO2/Ag coatings and no crystalline changed happened in the TiO2 structure. The reduction ratios on the TiO2/Ag coatings with 10 ppm AgNPs were as high as 94.8% and 95.6% for E. coli and S. aureus, respectively, and the TiO2/Ag coatings with 100-1000 ppm AgNPs exhibited 100% bactericidal activity against E. coli and S. aureus, which indicated the TiO2/Ag coatings with more than 10 ppm AgNPs had strong antibacterial activity. Moreover, the main factors influencing the antibacterial properties of TiO2/Ag coatings were discussed with grain size and the content of silver as well as the microstructure of the coatings. © 2015 Elsevier B.V. All rights reserved. Source


Dong W.,CAS Shanghai Institute of Ceramics | Zhu Y.,CAS Shanghai Institute of Ceramics | Zhang J.,CAS Shanghai Institute of Ceramics | Lu L.,CAS Shanghai Institute of Ceramics | And 3 more authors.
Journal of Nanoscience and Nanotechnology | Year: 2013

Micro-porous titanium is coated with silver nanoparticles by using a simple chemical reduction method that exhibits excellent antibacterial ability. Scanning electron microscopy (SEM) shows that the silver nanoparticles with average sizes of about 100 nm are formed homogeneously on the micro-porous titanium surface. After the micro-porous Ti coated with silver nano particles is treated by heating, the average size of the silver nano particles is slightly increased, but the nano particles are more uniformly dispersed on the surface of the micro-porous titanium. X-ray diffraction (XRD) indicates that those nanoparticles are metallic silver produced on the micro-porous titanium surface. The samples of micro-porous titanium coated with silver nanoparticles inhibit the growth of Escherichia coli. Our results show that the electrical double layer of the samples play an important role in the antibiosis and this study opens a new window for antibacterial mechanism which may be suitable for the other antibacterial metallic materials. Copyright © 2013 American Scientific Publishers. Source


Qin L.,China Astronaut Researching and Training Center | Guo S.,China Astronaut Researching and Training Center | Ai W.,China Astronaut Researching and Training Center | Tang Y.,China Astronaut Researching and Training Center | And 2 more authors.
Advances in Space Research | Year: 2013

Growing plants can be used to clean waste water in bioregenerative life support system (BLSS). However, NaCl contained in the human urine always restricts plant growth and further reduces the degree of mass cycle closure of the system (i.e. salt stress). This work determined the effect of NaCl stress on physiological characteristics of plants for the life support system. Amaranth (Amaranthus tricolor L. var. Huahong) and leaf lettuce (Lactuca sativa L. var. Luoma) were cultivated at nutrient solutions with different NaCl contents (0, 1000, 5000 and 10,000 ppm, respectively) for 10 to 18 days after planted in the Controlled Ecological Life Support System Experimental Facility in China. Results showed that the two plants have different responses to the salt stress. The amaranth showed higher salt-tolerance with NaCl stress. If NaCl content in the solution is below 5000 ppm, the salt stress effect is insignificant on above-ground biomass output, leaf photosynthesis rate, Fv/Fm, photosynthesis pigment contents, activities of antioxidant enzymes, and inducing lipid peroxidation. On the other hand, the lettuce is sensitive to NaCl which significantly decreases those indices of growth and physiology. Notably, the lettuce remains high productivity of edible biomass in low NaCl stress, although its salt-tolerant limitation is lower than amaranth. Therefore, we recommended that amaranth could be cultivated under a higher NaCl stress condition (<5000 ppm) for NaCl recycle while lettuce should be under a lower NaCl stress (<1000 ppm) for water cleaning in future BLSS. © 2012 COSPAR. Published by Elsevier Ltd. All rights reserved. Source

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