Saturday, April 11, 2020


Research sheds light on how silver ions kill bacteria

REAL FACTS ABOUT SILVER DISINFECTION


bacteria
Credit: CC0 Public Domain
The antimicrobial properties of silver have been known for centuries. While it is still a mystery as to exactly how silver kills bacteria, University of Arkansas researchers have taken a step toward better understanding the process by looking at dynamics of proteins in live bacteria at the molecular level.
Traditionally, the antimicrobial effects of silver have been measured through bioassays, which compare the effect of a substance on a test organism against a standard, untreated preparation. While these methods are effective, they typically produce only snapshots in time, said Yong Wang, assistant professor of physics and an author of the study, published in the journal Applied and Environmental Microbiology.
Instead, Wang and his colleagues used an advanced imaging technique, called "single-particle-tracking photoactivated localization microscopy," to watch and track a particular  found in E. coli bacteria over time.
Researchers were surprised to find that silver ions actually sped up the dynamics of the protein, opposite of what they thought would happen.
"It is known that silver ions can suppress and kill bacteria," Wang said. "We thus expected that everything slowed down in the bacteria when treated with silver. But, surprisingly, we found that the dynamics of this protein became faster."
The researchers observed that silver ions were causing paired strands of DNA in the bacteria to separate, and the binding between the protein and the DNA to weaken. "Then the faster dynamics of the proteins caused by silver can be understood," said Wang. "When the protein is bound to the DNA, it moves slowly together with the DNA, which is a huge molecule in the bacteria. In contrast, when treated with silver, the proteins fall off from the DNA, moving by themselves and thus faster."
The observation of DNA separation caused by silver ions came from earlier work that Wang and colleagues had done with bent DNA. Their approach, now patent pending, was to put strain on DNA strands by bending them, thus making them more susceptible to interactions with other chemicals, including .
The National Science Foundation-funded study validated the idea of investigating the dynamics of single proteins in live bacteria. An approach that could help researchers understand the real-time responses of  to silver nanoparticles, which have been proposed for fighting against so-called "superbugs" that are resistant to commonly prescribed antibiotics.
"What we want to do eventually is to use the new knowledge generated from this project to make better antibiotics based on  nanoparticles," said Wang
More information: Asmaa A. Sadoon et al. Silver Ions Caused Faster Diffusive Dynamics of Histone-Like Nucleoid-Structuring Proteins in Live Bacteria, Applied and Environmental Microbiology (2020). DOI: 10.1128/AEM.02479-19

Video: How silver nanoparticles cut odors


How silver nanoparticles cut odors (video)
Credit: The American Chemical Society
Trendy workout clothes may advertise that special silver nanoparticles embedded in the fabric will cut the sweaty odor that builds up from repeated gym visits. It turns out there's some truth to these claims.
Silver can kill the bacteria that cause B.O., and new techniques, including nanotech, allow clothing manufacturers to incorporate  that doesn't come out in the wash or harm the environment. In this video, Reactions explains how all of that is possible.

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