New research findings from The University of Queensland have revealed that hollow nanospheres made from iron oxide hold promise as an antibacterial agent to fight diseases caused by microbial infections.

Australian Institute for Bioengineering and Nanotechnology researcher Professor Chengzhong (Michael) Yu said the rise of drug-resistant bacterial infections prompted the research team to search for an inorganic solution to this growing health problem.

Microbial infections are responsible for around 700,000 deaths worldwide annually, and this number is estimated to rise to a staggering 10 million per year by 2050.

“The overuse of antibiotics in daily life, agriculture and the food industry has led to a rise in bacteria that have adapted to become resistant to antibiotic drugs,” Professor Yu said.

To achieve their research goals, the team engineered a magnetic iron oxide nanoparticle, hollowed using a thermal calcination process that triggers internal oxidation. Iron oxide is a naturally occurring mineral, which has been approved by the US Food and Drug Administration and Australian Therapeutic Goods Administration for use in medicines and food.

“The magnetic iron oxide showed very positive results against bacterial infections, giving real hope that it has potential as a treatment. Just as importantly, cellular health was maintained, indicating that it would be a safe as well as effective antibacterial treatment,” he said.

Professor Yu said the hollow design of the nanospheres may also afford the added benefit of providing capacity to carry an antibiotic cargo.

“The hollow design lends itself to carrying antibiotics, which could provide a synergistic effect to overcome more resistant bacterial infections. Considering the number of deaths caused by infections globally, the potential implications of this finding for healthcare are significant.”

PhD student Yusilawati Ahmad Nor, first-author of the study published in Advanced Functional Materials, said laboratory testing of the nanospheres – performed on two common strains of bacteria, E. coli and S. epidermidis – showed strong antimicrobial effects. However, the effectiveness was dependant on the physical properties of the nanospheres.

“During the study, we discovered that the antibacterial effects varied depending on both the composition and structure of the nanoparticle,” Ms Ahmad Nor said.

“We engineered different variants of iron oxide hollow nanospheres made from hematite and magnetite, and found superior performance in the magnetite variety,” she said.

“The magnetite iron oxide reacted with the bacteria at an increased rate, causing it to leach iron ions and generate reactive oxygen to combat the bacteria. Interestingly, the rate of the leaching was highly dependent on the type of bacteria present.”

The study was performed in collaboration with UQ’s Queensland Alliance for Agriculture and Food Innovation. The research team are seeking industrial collaborations to extend the project to investigate other bacterial strains.

Research is also continuing to investigate the antibacterial properties of other magnetic iron oxide nanoparticles, as well as other advanced materials such as silica nanoparticles, to find the most effective composition and structure for combating bacterial infections.

The study of advanced materials such as antibacterial nanoparticles is one of AIBN’s core research strengths and aims to improve human health and agricultural sustainability.

Media: Darius Koreis, d.koreis@uq.edu.au, +61 7 3346 3962, +61 427 148 187; Professor Michael Yu, c.yu@uq.edu.au, +61 7 3356 3283. 

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