A fungal cell (green) that interacts with a nanotine layer of black phosphorus (red). The image has been enlarged 25,000 times. Credit: RMIT University
Nanothin antimicrobial coating can prevent and treat deadly infections.
Researchers have developed a new excellent layer that can be used on wound dressings and implants to prevent and treat potentially deadly bacteria and fungal infections.
The material is one of the thinnest antimicrobial coatings developed so far and is effective against a wide range of drug-resistant bacteria and fungal cells, while leaving human cells unharmed.
Antibiotic resistance is a major global threat to health, causing at least 700,000 deaths annually. Without the development of new antibacterial treatments, the death toll could rise to 10 million people a year by 2050, equivalent to $ 100 billion in healthcare costs.
Drug-resistant MRSA before and after exposure to the nanostain. Credit: RMIT University
Although the health burden of fungal infections is less recognized, they kill about 1.5 million people annually and increase the death toll. An emerging threat to COVID-19 patients admitted to the hospital is, for example, the common fungus, Aspergillus, which can cause fatal secondary infections.
The new layer of a team led by RMIT is based on an ultra-thin 2D material that has so far been mainly of interest to the next generation of electronics.
Studies on black phosphorus (BP) have indicated that it has antibacterial and antifungal properties, but the material has never been methodically investigated for possible clinical use.
The new research, published in the journal of the American Chemical Society Applied materials and interfaces, BP appears to be effective in killing microbes when spread in nanotine layers on surfaces such as titanium and cotton, which are used to make implants and wound dressings.
Candida auris fungus before exposure to ultra-thin layers of black phosphorus (left) and then (right). Credit: RMIT University
Aaron Elbourne, co-principal investigator, said it was important to find one material that could prevent 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 is becoming increasingly difficult,” Elbourne, a postdoctoral fellow at the School of Science, told RMIT.
‘We need smart new weapons for the war on super lice, which do not contribute to the problem of antimicrobial resistance.
‘Our nanotin layer is a double bug killer that works by tearing bacteria and fungal cells apart, something microbes struggle to adapt to. It will take millions of years for new defenses to develop naturally into such a deadly physical attack.
“While we need further research to apply this technology in clinical settings, it is an exciting new direction in the search for more effective ways to address this serious health challenge.”
E.coli bacteria before exposure to the nanothin antimicrobial layer (left) and thereafter (right). Credit: RMIT University
Associate Professor, Associate Professor Sumeet Walia, of RMIT Engineering, has previously led groundbreaking studies using BP for artificial intelligence technology and brain-mimicking electronics.
“BP breaks down in the presence of oxygen, which is normally a big problem for electronics and something we had to overcome with careful engineering to develop our technologies,” Walia said.
‘But it seems that materials that degrade easily with oxygen can be ideal for killing microbes – this is exactly what the scientists who worked on antimicrobial technologies were looking for.
“So our problem was solving it.”
How the nanothin bug killer works
As BP breaks down, it oxidizes the surface of bacteria and fungal cells. This process, known as cellular oxidation, eventually works to tear them apart.
In the new study, first author and PhD researcher Zo Shaw tested the effectiveness of nanotine layers of BP against five common bacterial strains, including E. coli and resistant MRSA, as well as five types of fungi, including Candida auris.
In just two hours, up to 99% of the bacterial and fungal cells were destroyed.
Dr. Aaron Elbourne, PhD researcher Zo Shaw and associate professor Sumeet Walia. Credit: RMIT University
What is important is that the BP also began to break down during that time and completely disintegrated 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 healing and healing human cells.
The researchers have now begun experimenting with different formulations to test the effectiveness on a variety of medically relevant surfaces.
The team would like 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 low-layer phosphorus as a fast-acting antimicrobial” by ZL Shaw, Sruthi Kuriakose, Samuel Cheeseman, Edwin LH Mayes, Alishiya Murali, Zay Yar Oo, Taimur Ahmed, Nhiem Tran, Kylie Boyce, James 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, Applied materials and interfaces.
DOI: 10.1021 / acsami.1c01739
The RMIT research team also included the following: 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).