Are Self-Sterilizing Microneedles Key to Safer Vaccines?

Researchers at the University of South Australia have developed a microneedle patch with antibacterial properties to make vaccinations safer than traditional needles or other microneedles.

Researchers at the University of South Australia may have found a way to make vaccinations safer. The team developed a microneedle patch loaded with antibacterial silver nanoparticles to provide a sterilization mechanism.

"Injections are one of the most common healthcare procedures used for vaccinations and curative care around the world," said Krasimir Vasilev, the lead researcher and a professor at the university's school of engineering. "But up to 40% of injections are given with improperly sterilized syringes and needles, placing millions of people at risk of contracting a range of illnesses or diseases."

The researchers tested the antibacterial efficacy of silver-loaded microneedles against bacteria associated with common skin infections, such as Golden staph, and found that the silver-loaded microneedle patches created a 24-hour bacteria-free zone around the patch administration site, a feature unique to the new technology.

The vaccination patch is made up of 250 needles — each 700 micron in height and 400 micron in diameter — which pierce only the top layer of the skin without reaching the underlying nerves. The microneedles are made from a biocompatible, water-soluble polymer that completely dissolves within one minute of application.

Vasilev said the patches are a few years away from commercialization but they have begun the trial process. The study was published as a cover story in Chemical Communications.

Another important feature of the patch is that the microneedles are dissolvable to eliminate the risk of reuse, one of the greatest causes of infection. 

“And by incorporating the antibacterial silver nanoparticles into the dissolvable microneedles, we’ve created a very promising vehicle for safe vaccine and drug delivery around the world,” Vasilev said.

The Australian researchers are not the first group to explore the promise of using dissolvable microneedles for vaccinations. Back in 2009, MD+DI reported that researchers from the Georgia Institute of Technology and Emory University (both in Atlanta, GA) were studying the use of microneedles as a less painful and lower-cost drug-delivery method. Their findings showed that delivering a flu vaccine through microneedle-based skin patches were just as effective in mice as delivery via intramuscular hypodermic immunization.

Other researchers have also been pursuing silver for its antimicrobial properties. It's not the silver itself that is microbial, but rather the silver ions that are released when the metal is exposed to moisture. The ions attack bacteria with multiple modes of action.

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