Optimization of Silver Ion Release from Silver-Ceramic Porous Media for Household Level Water Purification

A novel method has been developed to produce zerovalent silver nanopatches in a porous ceramic tablet using only clay, sawdust, water, and silver nitrate as precursors. When placed in 10 L of water, the silver nanopatches (2 to 3 nm diameter per patch) are gradually oxidized to produce silver ions, which diffuse out of the tablet into the bulk solution. The objective of this work is to optimize the silver-ceramic design to increase the rate of silver ion release from the tablet to further improve disinfection kinetics. To meet this objective, ceramic tablets were fabricated in different ways and tested for silver ion release into water over 8 to 24 h periods. Silver addition had an approximately linear effect on silver ion. Grinding the tablet into different particle sizes (4–60 mesh) had the most significant effect on silver release. However, if this ground fraction is compartmentalized into a fabric bag, silver levels produced in the water drop back to levels comparable to the single tablet form. Based on these results, 1 and 2 cm ceramic cubes were manufactured and represented a reasonable compromise between silver release and usability. Disinfection experiments on these silver-ceramic cubes resulted in effective disinfection of E. coli in laboratory experiments.

Download Full-text

Controlling Silver Ion Release from Ag-Based Nanocoatings by Plasma Surface Engineering

Materials Science Forum ◽

10.4028/www.scientific.net/msf.941.1625 ◽

2018 ◽

Vol 941 ◽

pp. 1625-1631 ◽

Cited By ~ 1

Author(s):

Linda Bonilla-Gameros ◽

Maxime Cloutier ◽

Vanessa Montaño-Machado ◽

Pascale Chevallier ◽

Diego Mantovani

Keyword(s):

Surface Engineering ◽

Silver Ions ◽

Silver Ion ◽

Ion Release ◽

Plasma Surface ◽

Antibacterial Coatings ◽

Environmental Surfaces ◽

Novel Strategy ◽

Silver Release ◽

Silver Ion Release

Environmental surfaces have been widely recognized as an important source of hospital-associated transmissions. A number of silver-based antibacterial coatings have been reported in the literature. However, the success of any antibacterial strategy depends on the ability to control the kinetics of the silver ions released from the coating. The novel strategy proposed in this work is based on plasma surface engineering for a controlled-release of silver ions. Plasma-based nanocoatings, plasma oxidation processes and surface patterning of silver coatings were designed and optimized. Surface analyses such as XPS and AFM, as well as silver ion release over 168 h, was evaluated by MIP-AES. Results showed that surface plasma engineering successfully allow tuning the silver release and bioactivity in Ag-containing antibacterial coatings.

Download Full-text

Effect of Silver Content on the Structure and Antibacterial Activity of Silver-Doped Phosphate-Based Glasses

Antimicrobial Agents and Chemotherapy ◽

10.1128/aac.00605-07 ◽

2007 ◽

Vol 51 (12) ◽

pp. 4453-4461 ◽

Cited By ~ 73

Author(s):

Sabeel P. Valappil ◽

David M. Pickup ◽

Donna L. Carroll ◽

Chris K. Hope ◽

Jonathan Pratten ◽

...

Keyword(s):

Glass Structure ◽

Silver Ions ◽

Structural Rearrangement ◽

Bactericidal Effect ◽

High Energy ◽

Silver Ion ◽

Ion Release ◽

Bactericidal Agent ◽

Silver Ion Release

ABSTRACT Staphylococcus aureus can cause a range of diseases, such as osteomyelitis, as well as colonize implanted medical devices. In most instances the organism forms biofilms that not only are resistant to the body's defense mechanisms but also display decreased susceptibilities to antibiotics. In the present study, we have examined the effect of increasing silver contents in phosphate-based glasses to prevent the formation of S. aureus biofilms. Silver was found to be an effective bactericidal agent against S. aureus biofilms, and the rate of silver ion release (0.42 to 1.22 μg·mm−2·h−1) from phosphate-based glass was found to account for the variation in its bactericidal effect. Analysis of biofilms by confocal microscopy indicated that they consisted of an upper layer of viable bacteria together with a layer (∼20 μm) of nonviable cells on the glass surface. Our results showed that regardless of the silver contents in these glasses (10, 15, or 20 mol%) the silver exists in its +1 oxidation state, which is known to be a highly effective bactericidal agent compared to that of silver in other oxidation states (+2 or +3). Analysis of the glasses by 31P nuclear magnetic resonance imaging and high-energy X-ray diffraction showed that it is the structural rearrangement of the phosphate network that is responsible for the variation in silver ion release and the associated bactericidal effectiveness. Thus, an understanding of the glass structure is important in interpreting the in vitro data and also has important clinical implications for the potential use of the phosphate-based glasses in orthopedic applications to deliver silver ions to combat S. aureus biofilm infections.

Download Full-text