Scientists have developed a new type of enzyme, called a NanoZyme, which is triggered by light to produce free radicals that kill bacteria. The technology could be used one day to fight infections by sterilising high-risk surfaces in areas such as hospitals and public bathrooms.

Researchers from RMIT University in Melbourne created these NanoZymes from tiny nanorods of cupric oxide. The rods themselves are 1,000 times smaller than the thickness of a human hair.

Lead researcher Professor Vipul Bansal, Australian Future Fellow and Director of RMIT’s Sir Ian Potter NanoBioSensing Facility, said that these NanoZymes exceed nature’s inbuilt ability to kill bacteria. This is because more natural mechanisms do not respond to external triggers such as light.

“For a number of years we have been attempting to develop artificial enzymes that can fight bacteria, while also offering opportunities to control bacterial infections using external ‘triggers’ and ‘stimuli,’” he said.

Zapping bacteria on the nanoscale

The NanoZymes combine light with moisture to create highly reactive oxygen species such as OH radicals that degrade organic matter. These radicals rapidly break down and kill bacteria they come in contact with, and are the same compounds that can degrade healthy cells within smokers.

The NanoZymes also never get consumed in the reaction and are able to continuously produce free radicals using light and surrounding moisture. This means they can be applied to a surface to potentially fight bacteria over the long-term.

When exposed to a flash of white light, the NanoZymes increase their activity by over 20 times. The resulting free radicals form holes in bacterial cells and kill them rapidly as can be seen in the images below.

A 3D rendering of live bacteria A 3D rendering of dead bacteria – the bacteria have been eaten by the NanoZymes

Because the NanoZymes are triggered by light to produce a burst of free radicals, this also prevents bacteria from building up a resistance, Bansal said.

This technique could be used to fight a number of harmful bacteria including E coli, which causes dysentery and gastroenteritis, and Golden Staph, which is a major cause of hospital-acquired secondary infections and is often antibiotic-resistant.

Sprays, coatings and more

There are many potential uses of this technology, Bansal said, with the NanoZyme solution either being sprayed onto surfaces or mixed into paints, ceramics or other consumer products.

“This next generation of nanomaterials are likely to offer new opportunities in bacteria-free surfaces and controlling spread of infections in public hospitals.”

This could mean sterile surfaces in areas which otherwise may have had high levels of bacteria such as in doctor’s waiting rooms, hospitals or public restrooms. The technology could even extend to self-cleaning toilet bowls.

There is also a potential to use this technology on external wounds to fight infection. In short, the NanoZymes would mimic the body’s self-healing process by degrading healthy cells as well as bacteria within the wound, Bansal said.

“When bacteria infect a wound, they attack the cells there. What the body does is it starts killing the body cells around the wound so the bacteria doesn’t get food.”

Stepping outside of the lab

The next phase will be to test these NanoZymes outside of the lab in sunlight to look at their long-term performance within consumer products. Up to now, they have only been tested in a laboratory setting using light from torches and similar manmade sources.

“The next step will be to validate the bacteria-killing and wound-healing ability of these NanoZymes outside of the lab,” Bansal said.

As the intensity of the torch light used by RMIT is similar to that from the Sun, the NanoZymes should technically work in natural sunlight as well.

Finding industry funding

With this technology’s huge potential, RMIT is looking for interested industrial parties for joint product development. Three firms have already approached the university about potentially testing the NanoZymes in consumer products for mass production.

“As an academic institution, our core business is not to make money and manufacture things. We need active partnerships from industry partners who see value in this and who can fund the next stage of the project,” Bansal said.

There is always a risk when universities attempt to bring new technologies onto the market, as many stay in the lab forever after failing to get industry funding, he added.

Fighting the fear factor

Another hurdle is that the use of the word ‘nanoparticles’ in a consumer product comes with added regulation and possible public scepticism. However, this was nothing to be feared, Bansal said.

“Nanomaterials are not something new. They’ve been used for the past several decades.”

For instance, certain paints already contain nanoparticles such as titanium oxide that creates an added sheen. These same titanium particles are also used in sunscreen to block solar radiation.

“We just need a bit more awareness. Companies need to be bold and say, ‘Yes, we have nanoparticles and nanoparticle components in our products’.”

This research has been published in the journal ACS Applied Nano Materials and was created with cooperation between RMIT, the University of Sydney, and India’s Ahmedabad University.

All images are attributed to Dr Chaitali Dekiwadia of the RMIT Microscopy and Microanalysis Facility.

Article by Miklos Bolza

Miklos Bolza graduated with an honours degree in science from UNSW (majoring in maths and physics), now works as a freelance science journalist, and can’t wait until space tourism really ramps up.