Are silver nanoparticles a silver bullet against microbes?

Antimicrobials are used to kill or slow the growth of bacteria, viruses and other microorganisms. They can be in the form of antibiotics, used to treat bodily infections, or as an additive or coating on commercial products used to keep germs at bay. These life-saving tools are essential to preventing and treating infections in humans, animals and plants, but they also pose a global threat to public health when microorganisms develop resistance to them, a concept known as antimicrobial resistance.

One of the main drivers of antimicrobial resistance is the misuse and overuse of antimicrobial agents, which includes silver nanoparticles, an advanced material with well-documented antimicrobial properties. It is increasingly used in commercial products that boast enhanced germ-killing performance - it has been woven into textiles, coated onto toothbrushes, and even mixed into cosmetics as a preservative.

The Gilbertson Group at the University of Pittsburgh Swanson School of Engineering used laboratory strains of E.coli to better understand bacterial resistance to silver nanoparticles and attempt to get ahead of the potential misuse of this material. The team recently published their results in Nature Nanotechnology.

"Bacterial resistance to silver nanoparticles is understudied, so our group looked at the mechanisms behind this event," said Lisa Stabryla, lead author on the paper and a recent civil and environmental PhD graduate at Pitt. "This is a promising innovation to add to our arsenal of antimicrobials, but we need to consciously study it and perhaps regulate its use to avoid decreased efficacy like we've seen with some common antibiotics."

Stabryla exposed E.coli to 20 consecutive days of silver nanoparticles and monitored bacterial growth over time. Nanoparticles are roughly 50 times smaller than a bacterium.

"In the beginning, bacteria could only survive at low concentrations of silver nanoparticles, but as the experiment continued, we found that they could survive at higher doses," Stabryla noted. "Interestingly, we found that bacteria developed resistance to the silver nanoparticles but not their released silver ions alone."

The group sequenced the genome of the E.coli that had been exposed to silver nanoparticles and found a mutation in a gene that corresponds to an efflux pump that pushes heavy metal ions out of the cell.

"It is possible that some form of silver is getting into the cell, and when it arrives, the cell mutates to quickly pump it out," she added. "More work is needed to determine if researchers can perhaps overcome this mechanism of resistance through particle design."

The group then studied two different types of E.coli: a hyper-motile strain that swims through its environment more quickly than normally motile bacteria and a non-motile strain that does not have physical means for moving around. They found that only the hyper-motile strain developed resistance.

"This finding could suggest that silver nanoparticles may be a good option to target certain types of bacteria, particularly non-motile strains," Stabryla said.

In the end, bacteria will still find a way to evolve and evade antimicrobials. The hope is that an understanding of the mechanisms that lead to this evolution and a mindful use of new antimicrobials will lessen the impact of antimicrobial resistance.

"We are the first to look at bacterial motility effects on the ability to develop resistance to silver nanoparticles," said Leanne Gilbertson, assistant professor of civil and environmental engineering at Pitt. "The observed difference is really interesting and merits further investigation to understand it and how to link the genetic response - the efflux pump regulation - to the bacteria's ability to move in the system.

"The results are promising for being able to tune particle properties for a desired response, such as high efficacy while avoiding resistance."

Stabryla LM, Johnston KA, Diemler NA, Cooper VS, Millstone JE, Haig SJ, Gilbertson LM.
Role of bacterial motility in differential resistance mechanisms of silver nanoparticles and silver ions.
Nat Nanotechnol. 2021 Jun 21. doi: 10.1038/s41565-021-00929-w

Most Popular Now

Positive new data for Johnson & Johnson single…

Johnson & Johnson (NYSE: JNJ) (the Company) announced data that demonstrated its single-shot COVID-19 vaccine generated strong, persistent activity against the rapidly sp...

GSK and Alector announce global collaboration in i…

GlaxoSmithKline plc (LSE/NYSE: GSK) and Alector (Nasdaq: ALEC), today announced a strategic global collaboration for the development and commercialisation of two clinical...

Tezepelumab granted Priority Review by U.S. FDA

Amgen (NASDAQ:AMGN) announced that the U.S. Food and Drug Administration (FDA) has accepted a Biologics License Application (BLA) and granted Priority Review for tezepelu...

One shot of the Sputnik V vaccine triggers strong …

A single dose of the Sputnik V vaccine may elicit significant antibody responses against SARS-CoV-2, finds a study published July 13 in the journal Cell Reports Medicine...

Are silver nanoparticles a silver bullet against m…

Antimicrobials are used to kill or slow the growth of bacteria, viruses and other microorganisms. They can be in the form of antibiotics, used to treat bodily infections...

"Long COVID": More than a quarter of COV…

In a new study of adults from the general population who were infected with COVID-19 in 2020, more than a quarter report not having fully recovered after six to eight mon...

mRNA vaccines slash risk of COVID-19 infection by …

People who receive mRNA COVID-19 vaccines are up to 91 percent less likely to develop the disease than those who are unvaccinated, according to a new nationwide study of ...

Cancer cells eat themselves to survive

It is the membrane of cancer cells that is at the focus of the new research now showing a completely new way in which cancer cells can repair the damage that can otherwis...

U.S. FDA grants Priority Review for the Biologics …

Pfizer Inc. (NYSE: PFE) and BioNTech SE (Nasdaq: BNTX) announced that the U.S. Food and Drug Administration (FDA) granted Priority Review designation for the Biologics Li...

Collaboration between AbbVie, Biogen and Pfizer cr…

The access to the world's largest browsable resource linking rare protein-coding genetic variants to human health and disease was launched through a genetic exome sequenc...

Artificial intelligence could be new blueprint for…

Writing in the July 12, 2021 online issue of Nature Communications, researchers at University of California San Diego School of Medicine describe a new approach that uses...

Anti-tumor agent from the intestine

It is believed to be involved in the development of chronic inflammatory intestinal diseases, to trigger diabetes, to be responsible for obesity, even neurological diseas...