Tag Archives: Islamic Azad University

Treating bandages with enzymes and polyethylene glycol or cellulase* could make antibacterial nanoparticles better adhere

2 Replies

It’s been a while since I’ve featured research from Iran. This work is focused on bandages, burns, and nanoparticles according to an Oct. 18, 2016 news item on Nanowerk (Note: A link has been removed),

Pre-treating the fabric surface of the bandages used to treat burns with enzymes and polyethylene glycol or cellulase may promote the adhesion of antibacterial nanoparticles and improve their bacteria-repelling ability. These are the findings of a group of scientists from the Islamic Azad University, Iran, published in The Journal of The Textile Institute (“NiO-/cotton- modified nanocomposite as a medication model for bacterial-related burn infection”).

An Oct. 18, 2016 Taylor & Francis (Publishing) Group press release (received via email), which originated the news item, expands on the theme,

Injuries caused by burns are a global health problem, with the World Health Organisation citing 195,000 deaths per year worldwide as a result of burns from fires alone. Burn injuries are particularly susceptible to infections, hospital-acquired or otherwise, with the bacteria Pseudomonas aeruginosa accounting for over half of all severe burn infections.

Noble metal (particularly silver) antimicrobials have long been identified as having potential for combating bacterial infection; however, there are concerns about dressings adhering to wounds and toxic effects on skin cells. Currently, scientists are researching nanoparticles which can be used to introduce these antimicrobial properties into the textiles used in dressings.

The authors of this paper have studied 150 cases to identify the most common infections in burns. In the paper, they also identified a method for giving cotton bandages antibacterial properties by coating the fabric surface with a Nickel oxide (NiO)/organic polymer/enzyme matrix in order to promote their bacteria-resistant qualities and suitability for use on burn victims.

Pseudomonas and Staphylococci infections emerged as the two most common pathogens in the Iran Burn Centre, where the study took place, and the authors evaluated their design of the bandage against these as well as fifteen other strains of bacteria. They conclude by proposing further studies into the combination of bactericidal polymers with bacteria-killing metal-oxide nanoparticles in cotton fabrics. Whilst their current design does not meet the criteria for a susceptibility test, they are hopeful that further studies will reveal the clinical relevance of their design.

Here’s a link to and a citation for the paper,

NiO-/cotton- modified nanocomposite as a medication model for bacterial-related burn infections by Azadeh Basiri, Nasrin Talebian & Monir Doudi. The Journal of The Textile Institute http://dx.doi.org/10.1080/00405000.2016.1222863
Pages 1-9 Published online: 12 Sep 2016

This paper is behind a paywall.

*’Cellulase’ changed to ‘Cellulose’ Nov. 15, 2016 at 1832 PT and changed back again on Nov. 16, 2016. Sorry for the confusion but by the time I published this piece I’d forgotten checking to confirm the existence of cellulase.

Fewer silver nanoparticles washed off coated textiles

Leave a reply

This time I have two complementary tidbits about silver nanoparticles, their use in textiles, and washing. The first is a June 30, 2014 news item on Nanowerk, with the latest research from Empa (Swiss Federal Laboratories for Materials Science and Technology) on silver nanoparticles being sloughed off textiles when washing them,

The antibacterial properties of silver-coated textiles are popular in the fields of sport and medicine. A team at Empa has now investigated how different silver coatings behave in the washing machine, and they have discovered something important: textiles with nano-coatings release fewer nanoparticles into the washing water than those with normal coatings …

A June 30,  2014 Empa news release, which originated the news item, describes the findings in more detail,

If it contains ‘nano’, it doesn’t primarily leak ‘nano’: at least that’s true for silver-coated textiles, explains Bernd Nowack of the «Technology and Society» division at Empa. During each wash cycle a certain amount of the silver coating is washed out of the textiles and ends up in the waste water. [emphasis mine] Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles. That’s quite the opposite to ordinary coatings, where a lot of different silver particles were found. Moreover, nano-coated silver textiles generally lose less silver during washing. This is because considerably less silver is incorporated into textile fabrics with nano-coating, and so it is released in smaller quantities for the antibacterial effect than is the case with ordinary coatings. A surprising result that has a transformative effect on future analyses and on the treatment of silver textiles. «All silver textiles behave in a similar manner – regardless of whether they are nano-coated or conventionally-coated,» says Nowack. This is why nano-textiles should not be subjected to stricter regulation than textiles with conventional silver-coatings, and this is relevant for current discussions concerning possible special regulations for nano-silver.

But what is the significance of silver particles in waste water? Exposed silver reacts with the (small quantities of) sulphur in the air to form silver sulphide, and the same process takes place in the waste water treatment plant. The silver sulphide, which is insoluble, settles at the bottom of the sedimentation tank and is subsequently incinerated with the sewage sludge. So hardly any of the silver from the waste water remains in the environment. Silver is harmless because it is relatively non-toxic for humans. Even if silver particles are released from the textile fabric as a result of strong sweating, they are not absorbed by healthy skin.

I’ve highlighted Nowack’s name as he seems to have changed his opinions since I first wrote about his work with silver nanoparticles in textiles and washing in a Sept. 8, 2010 posting,

“We found that the total released varied considerably from less than 1 to 45 percent of the total nanosilver in the fabric and that most came out during the first wash,” Bernd Nowack, head of the Environmental Risk Assessment and Management Group at the Empa-Swiss Federal Laboratories for Materials Testing and Research, tells Nanowerk. “These results have important implications for the risk assessment of silver textiles and also for environmental fate studies of nanosilver, because they show that under certain conditions relevant to washing, primarily coarse silver-containing particles are released.”

How did the quantity of silver nanoparticles lost in water during washing change from “less than 1 to 45 percent of the total nanosilver in the fabric” in a 2010 study to “Empa analysed this water; it turned out that nano-coated textiles release hardly any nano-particles” in a 2014 study? It would be nice to find out if there was a change in the manufacturing process and whether or not this is global change or one undertaken in Switzerland alone.

Here’s a link to and a citation for the Empa paper,

Presence of Nanoparticles in Wash Water from Conventional Silver and Nano-silver Textiles by Denise M. Mitrano, Elisa Rimmele, Adrian Wichser, Rolf Erni, Murray Height, and Bernd Nowack. ACS Nano, Article ASAP DOI: 10.1021/nn502228w Publication Date (Web): June 18, 2014

Copyright © 2014 American Chemical Society

This paper is behind a paywall.

The second tidbit is from Iran and may help to answer my questions about the Empa research. According to a July 7, 2014 news item on Nanowerk (Note: A link has been removed),

Writing in The Journal of The Textile Institute (“Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics”), researchers from Islamic Azad University in Iran, describe the best arrangement for increasing the antibacterial properties of textile products by studying various structures of silver nanoparticles.

A July 7, 2014 news release from the Iran Nanotechnology Initiative Council (INIC), which originated the news item, provides more details,

By employing the structure presented by the researchers, the amount of nanoparticles stabilization on the fabric and the durability of its antibacterial properties increase after washing and some problems are solved, including the change in the fabric color.

Using the results of this research creates diversity in the application of various structures of nanoparticles in the complementary process of cotton products. Moreover, the color of the fabric does not change as the amount of consumed materials decreases, because the excess use of silver was the cause of this problem. On the other hand, the stability and durability of nanoparticles increase against standard washing. All these facts result in the reduction in production cost and increase the satisfaction of the customers.

The researchers have claimed that in comparison with other structures, hierarchical structure has much better antibacterial activity (more than 91%) even after five sets of standard washing.

This work on morphology would seem to answer my question about the big difference in Nowack’s description of the quantity of silver nanoparticles lost due to washing. I am assuming, of course, that something has changed with regard to the structure and/or shape of the silver nanoparticles coating the textiles used in the Empa research.

Getting back to the work in Iran, here’s a link to and a citation for the paper,

Effect of silver nanoparticles morphologies on antimicrobial properties of cotton fabrics by Mohammad Reza Nateghia & Hamed Hajimirzababa. The Journal of The Textile Institute Volume 105, Issue 8, 2014 pages 806-813 DOI: 10.1080/00405000.2013.855377 Published online: 21 Jan 2014

This paper is behind a paywall.