Scientists Harness Gold Nanoparticles to Fight Infection Without Antibiotics

A new animal study uses gold nanoparticles for both creating images of and destroying biofilms on teeth and skin wounds.

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What if you could wield a laser sword against microscopic invaders, not in a galaxy far, far away, but in your own body?

Scientists have developed a technique using laser-heated gold nanoparticles to visualize and destroy bacterial biofilms. This approach, tested on rodent teeth and skin wounds, may someday potentially replace antibiotics and treat drug-resistant superbugs.

New Therapy Fights Bacteria Without Antibiotics

Researchers at the University of Pennsylvania and Stanford University have developed a novel technique using sugar-coated gold nanoparticles. When heated by near-infrared lasers, these nanoparticles can both show and destroy biofilms in infected teeth and skin wounds of rats and mice.

Biofilms are groups of tiny living things that cling to surfaces. These surfaces can be nonliving, such as rocks in a stream, or parts of animals, such as skin or gut lining.

The study, published in The Journal of Clinical Investigation, demonstrated these dual-purpose nanoparticles’ diagnostic and therapeutic potential in eliminating entrenched bacteria and viruses.

“We have developed a highly innovative and clinically translatable infectious treatment technique,” the study’s lead author, Maryam Hajfathalian, who holds a doctorate in mechanical engineering, told The Epoch Times. “[It’s a] rapid, drug-free method for wound and skin infection imaging and treatments.”

It’s a new way to clean teeth and wounds using tiny gold particles and light, she said.

“This is the first time that we have used engineered gold nanoparticles to eradicate oral biofilms using photothermal therapy,” Hajfathalian said.

According to Hajfathalian, these particles work quickly, killing harmful bacteria in less than one minute without broad-spectrum antibiotics. Because they work so well, scientists may be able to make new products such as special mouthwash, sticky strips, or bandages that use light to clean wounds.

The research received support from several National Institutes of Health branches, including the National Institute of Biomedical Imaging and Bioengineering.

“With this platform, you can bust biofilms without surgically debriding infections, which can be necessary when using antibiotics,” Luisa Russell, program director in the National Institute of Biomedical Imaging and Bioengineering’s Division of Discovery Science and Technology, said in a statement.

The method could be beneficial for people who can’t take standard medications. It works even for those who are allergic to antibiotics or have infections that don’t respond to typical treatments.

“The fact that this method is antibiotic-free is a huge strength,” said Russell, who holds a doctorate in materials science and engineering.

Photothermal therapy was nearly 100 percent effective at killing biofilms, the study found.

“The treatment method is especially fast for the oral infection,” Hajfathalian said. “We applied the laser for one minute, but really, in about 30 seconds, we’re killing basically all of the bacteria.”

The researchers noted that they hope further tests will show if this strategy can prevent cavities and accelerate healing.

What’s in Light-Based Treatment?

To understand how this light-based treatment works, one must first understand biofilms.

Biofilms

Biofilms are communities of microorganisms that adhere to surfaces in moist environments and reproduce. They form when bacteria secrete a slimy, glue-like substance, creating structures such as dental plaque, shower slime, or coatings on rocks and even human bodies.

Biofilms can be made up of single or multiple species of microbes, including bacteria and fungi, according to the Microbiology Society. These structures enhance microbial survival by providing support and protection against threats such as antimicrobials and immune responses.

Biofilm infections account for as much as 80 percent of all infections in humans and animals, and they often delay wound healing. They can cause various issues, from gum disease to urinary tract infections, and may even attach to medical devices, including pacemakers and contact lenses.

According to the Microbiology Society, bacteria in biofilms can be 1,000 times more resistant to antibiotics than free-floating bacteria, making them a major cause of treatment failure.

The dense network of proteins and carbohydrates in biofilms can prevent antibiotics from reaching the microbes, according to Hajfathalian.

“Biofilms are difficult to treat with existing clinical therapies due to antimicrobial resistance,” she said. “Studies indicate that biofilm infections, once established, cannot be treated by antibiotics alone in most cases. Therefore, a critical need exists to effectively diagnose and treat biofilm infections.”

Noble Metal Nanoparticles

Invisible to the naked eye, nanoparticles measure from 1 nanometer to 100 nanometers. Gold nanoparticles absorb light in visible and near-infrared regions. Near-infrared lasers emit radiation that doesn’t damage tissues and can promote cell regeneration and improve blood circulation, which promotes faster healing.

Noble metal nanoparticles are microscopic particles made from noble metals—metals resistant to corrosion and oxidation in moist air. The most common noble metals are gold, silver, and platinum. Potential applications include drug delivery and thermal ablation, which uses heat to remove unwanted body tissue.

In a review article published in Frontiers in Chemistry, researchers from Malaysia, India, and Saudi Arabia note that noble metal nanoparticles are used as antimicrobial agents because of their stability and biocompatibility. Their small size and high surface-to-volume ratio allow them to penetrate bacterial membranes effectively.

“The metal-based nanoparticles seem to have a commanding role in the [21st] century because of their vital role in nanomedicine and other biological applications,” the authors wrote. “The nanoparticles can be fabricated by using several synthetic routes and effectively used in various nanomedical and biological applications.”

Gold nanoparticles, which are nontoxic, are promising for photothermal therapy because they convert light energy into heat to kill pathogens, according to the authors of the new study. They also emit ultrasound waves in response to light, enabling photoacoustic imaging (a noninvasive way to take detailed pictures inside the body using light).

A New Frontier in Medicine?

Scientists may be entering a new frontier in infection treatment that potentially rivals the discovery of antibiotics.

“As scientists, our goal is to explore innovative approaches to combat infectious diseases,” Hajfathalian said. “We are excited about the prospects and look forward to advancing our research through animal studies and clinical trials.”

In addition to her work on nanoparticles for photothermal therapy, she and her colleagues are investigating alternative treatments to reduce antibiotic reliance, including phage therapy. This treatment uses bacteriophages, viruses that selectively target and kill specific bacteria.

In her review published in WIREs Nanomedicine and Nanobiotechnology, Hajfathalian reported that complex metal nanostructures show promise for personalized treatments. While U.S. Food and Drug Administration (FDA) approval for clinical trials is pending, preliminary results indicate that these nanostructures have high targeting capability, biocompatibility, and stability, making them promising for real-world clinical imaging and treatment, according to Hajfathalian.

Future research will investigate nanoparticles’ effectiveness against biofilm infections in catheters, heart valves, lungs, and prosthetic joints.

All That Glitters Is Not Necessarily Gold

Mansoor Amiji, a professor at Northeastern University in Boston with a doctorate in pharmaceutical sciences, warns of potential issues with the internal use of metal nanoparticles.

While effective for surface infections, there are safety concerns about gold particles entering the body, he said.

“What happens to that gold once it’s inside? Are there any potential toxicities associated with accumulation inside the body?” Amiji told The Epoch Times.

Photothermal therapy isn’t new and has been applied to accessible tumors, he noted, emphasizing the need for further study on the safety and broad-spectrum effectiveness of metal nanoparticles against various organisms.

“There is an urgent need to create better antibiotics as well as these non-antibiotic agents that we have a potential to use for infection,” Amiji said.

He said he doesn’t foresee nanoparticles necessarily replacing antibiotics but thinks that they could allow scientists to “cast a wider net” in the search for non-antibiotic agents to cure disease.