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New Nanotech destroys bacteria and fungal cells, leaving human cells undamaged

Fungal cell and BP

A fungal cell (green) that interacts with a nanothin layer of black phosphorus (red). The image is enlarged 25,000 times. Credit: RMIT University

Nanothin antimicrobial coating could prevent and treat potentially fatal infections.

Researchers have developed a new superbug-destroying coating that can be used on wound dressings and implants to prevent and treat potentially deadly bacterial and fungal infections.

The material is one of the thinnest antimicrobial coatings developed to date and is effective against a wide range of drug-resistant bacteria and fungal cells while leaving human cells undamaged.

Antibiotic resistance is a major global health threat that causes at least 700,000 deaths a year. Without the development of new antibacterial therapies, the death toll could rise to 1

0 million people a year by 2050, equivalent to $ 100 trillion in health care costs.

MRSA Nanothin Antimicrobial Coating

Drug-resistant MRSA before and after exposure to the nano-coating. Credit: RMIT University

While the health burden of fungal infections is less recognized, globally they kill about 1.5 million people each year and the number of deaths is growing. A growing threat to hospitalized COVID-19 patients is, for example, the common fungus, Aspergillus, which can cause fatal secondary infections.

The new coating from a team led by RMIT is based on an ultra-thin 2D material, which until now has primarily been of interest to the next generation of electronics.

Studies on black phosphorus (BP) have shown that it has some antibacterial and antifungal properties, but the material has never been studied methodically for potential clinical use.

The new research, published in the American Chemical Society’s journal Materials and interfaces used, reveals that BP is effective at killing microbes when spread in nanothine layers on surfaces such as titanium and cotton used to make implants and wound dressings.

Candida auris fungus black phosphorus

Candida auris fungus before exposure to ultra-thin layers of black phosphorus (left) and after (right). Credit: RMIT University

Co-lead researcher Dr. Aaron Elbourne said it was a significant step forward in finding a material that could prevent both bacterial and fungal infections.

“These pathogens are responsible for massive health burdens, and as drug resistance continues to grow, our ability to treat these infections becomes increasingly difficult,” said Elbourne, a postdoctoral fellow at the School of Science at RMIT.

“We need smart new weapons for the war against superbugs that do not contribute to the problem of antimicrobial resistance.

“Our nanothin coating is a double belly killer that works by tearing bacteria and fungal cells apart, something microbes will struggle to adapt to. It would take millions of years to naturally develop new defenses for such a deadly physical attack.

“While we need further research to be able to apply this technology in clinical settings, it is an exciting new direction in the search for more effective ways to tackle this serious health challenge.”

E coli Nanothin Antimicrobial Coating

E. coli bacteria before exposure to the antimicrobial coating of nanothine (left) and after (right). Credit: RMIT University

Co-lead researcher associate professor Sumeet Walia, from RMIT’s School of Engineering, has previously led groundbreaking research using BP into artificial intelligence technology and brain-mimicking electronics.

“BP is collapsing in the presence of oxygen, which is usually a big problem for electronics and something we had to overcome with careful precision engineering to develop our technologies,” Walia said.

“But it turns out that materials that are easily degraded with oxygen can be ideal for killing microbes – that’s exactly what researchers working on antimicrobial technologies were looking for.

“So our problem was their solution.”

How nanothin bug killer works

When BP breaks down, it oxidizes the surface of bacteria and fungal cells. This process, known as cellular oxidation, ultimately works to tear them apart.

In the new study, first author and PhD researcher Zo Shaw tested the effectiveness of nanothine layers of BP against five common bacterial strains, including E. coli and drug-resistant MRSA, as well as five types of fungi, including Candida auris.

In just two hours, up to 99% of bacterial and fungal cells were destroyed.

Aaron Elbourne, Zo Shaw and Sumeet Walia

Dr. Aaron Elbourne, PhD researcher Zo Shaw and Associate Professor Sumeet Walia. Credit: RMIT University

It is important that BP also began to degrade itself at that time and was completely dissolved within 24 hours – an important feature that shows that the material would not accumulate in the body.

The laboratory study identified the optimal levels of BP that have a lethal antimicrobial effect while leaving human cells healthy and whole.

Researchers have now begun experimenting with different formulations to test the effectiveness of a range of medically relevant surfaces.

The team is keen to work with potential industry partners to further develop the technology for which a preliminary patent application has been filed.

Reference: “Broad-spectrum solvent-free layered black phosphorus as a rapid antimicrobial action” by ZL Shaw, Sruthi Kuriakose, Samuel Cheeseman, Edwin LH Mayes, Alishiya Murali, Zay Yar Oo, Taimur Ahmed, Nhiem Tran, Kylie Boyce, James Chapman, Christopher F McConville, Russell J. Crawford, Patrick D. Taylor, Andrew J. Christofferson, Vi Khanh Truong, Michelle JS Spencer, Aaron Elbourne and Sumeet Walia, April 12, 2021, Materials and interfaces used.
DOI: 10.1021 / acsami.1c01739

The RMIT research group also included: Sruthi Kuriakose and Dr. Taimur Ahmed (engineering); Samuel Cheeseman, dr. James Chapman, dr. Nhiem Tran, Professor Russell Crawford, dr. Vi Khanh Truong, Patrick Taylor, dr. Andrew Christofferson, Professor Michelle Spencer and dr. Kylie Boyce (science); and Dr. Edwin Mayes (RMIT Microscopy and Microanalysis Facility).

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