Cobalt-Doped Carbon Quantum Dots

Supercharged vinegar infused with nanoparticles may hold the key to defeating deadly antibiotic-resistant bacteria. 

New research suggests that incorporating bacteria-killing nanoparticles into vinegar could offer a novel approach to treating infections, including those resistant to antibiotics, potentially contributing to the global fight against antimicrobial resistance (AMR).

Scientists from the University of Bergen in Norway, QIMR Berghofer Medical Research Institute in Australia, and Flinders University in Australia have demonstrated that tiny carbon-based nanoparticles doped with cobalt can amplify the antimicrobial properties of acetic acid—the key component of vinegar. This combination has shown effectiveness against several bacterial species commonly associated with chronic wounds.

“We knew that vinegar, or acetic acid, has been traditionally regarded as antimicrobial, but its use in wound disinfection is limited due to insufficient activity against many bacterial strains at concentrations safe for skin (below 3%),” explained study author Professor Nils Halberg, a molecular biologist at QIMR Berghofer and the University of Bergen. “Our hypothesis was that even if it doesn’t eradicate all bacteria, it might weaken them, enhancing the efficacy of complementary treatments.”

Chronic wounds pose significant risks, particularly for the elderly, immunocompromised individuals, and those with conditions like diabetes. Compounding this challenge is the escalating threat of AMR, where pathogens evolve resistance to antimicrobial drugs, rendering infections harder to treat. The World Health Organization (WHO) identifies AMR, exacerbated by antibiotic overuse, as a leading global health threat. A 2019 study published in The Lancet attributed 1.27 million deaths directly to bacterial AMR, with an additional 4.95 million associated deaths.

Boosting Vinegar's Antimicrobial Power with Nanoparticles

The researchers developed "cobalt-containing carbon quantum dots"—ultra-small nanoparticles approximately 500,000 times smaller than a grain of sand. These particles enhance reactivity due to their high surface area, and the embedded cobalt generates reactive oxygen species that damage bacterial cells, leading to their rupture.

“Smaller nanoparticles are more reactive because of their increased surface area. The cobalt within the carbon nanoparticles produces reactive oxygen, which inflicts damage on the bacterial cell,” Halberg noted.

By combining these nanoparticles with a dilute 0.06% acetic acid solution, the team achieved potent antimicrobial effects against strains resistant to vinegar alone, including antibiotic-resistant Staphylococcus aureus (responsible for Staph infections), Escherichia coli (E. coli, prevalent in chronic wounds), and Enterococcus faecalis (another wound pathogen).

Laboratory and Animal Testing Yields Encouraging Results

Initial tests were conducted in vitro, exposing bacteria and human skin cells to the treatment in controlled laboratory conditions. The combination effectively eliminated the targeted bacteria without toxicity to human cells. Building on this, the researchers applied the treatment to wounds in mice infected with antibiotic-resistant bacteria. Results indicated successful clearance of infections, with no impairment to wound healing.

“Once exposed, the nanoparticles attack dangerous bacteria both inside the cell and on its surface, causing them to burst. Importantly, this approach is non-toxic to human cells and was shown to remove bacterial infections from mouse wounds without affecting healing,” stated co-author Dr. Adam Truskewycz, a molecular biologist at Flinders University.

The team envisions applications for vulnerable patient groups, such as those with type 1 diabetes who suffer from persistent infected wounds. The treatment could be administered directly after debridement (removal of dead or infected tissue), infused into bandages, or used as a wound irrigation solution.

A Strategy to Counter Antimicrobial Resistance

Halberg highlighted the broader implications of using nanoparticles to bolster traditional antimicrobials. “Bacteria evolve rapidly; sublethal exposures can foster resistance. Combining multiple antimicrobial agents increases the likelihood of eradication and hinders resistance development,” he said. “Our approach could serve as an alternative or adjunct to antibiotics. When bacteria adapt to one treatment, they alter their biochemistry—if the second agent targets that adaptation, the cumulative stress may overwhelm the cell.”

“Combination treatments like this may help curb antimicrobial resistance,” Halberg added.

While promising, the technology requires further validation through pre-clinical and clinical trials before human application.