One of the many aspects of our daily lives that have changed because of the COVID-19 pandemic is the way we treat surfaces. Many people across the globe have been paying significantly more attention to keeping surfaces in their living and working environment sparkling clean—a habit that is most certainly to remain.
Given that, wouldn’t it be nice if surfaces are capable of self-sanitizing? Such technology will be a Holy Grail particularly for healthcare institutions like hospitals and nursing homes, which can be a hotbed of nosocomial infections and antibiotic-resistant microbes.
For many centuries, surfaces made of copper and its alloys have been used as disinfecting agents, even before the concept of microbes was made clear. However, their efficacy is still unsatisfactory. “To break pathogen transmission over surface contact or airborne transmission, the rapid killing of microbes is crucial,” said Yugen Zhang, Senior Principal Investigator and Group Leader at A*STAR’s Institute of Bioengineering and Bioimaging (IBB) and A*STAR scholarship recipient. “Although copper surfaces can kill 99.9% of microorganisms in two hours, the multifold transmission may have already occurred within this period.”
In collaboration with the National Centre for Infectious Diseases (NCID) and Tan Tock Seng Hospital (TTSH), Zhang together with co-corresponding author of the study, Guangshun Yi, and their team, embarked on a quest to improve the self-sanitizing capability of surfaces. Inspired by the effectiveness of nanostructured cicada wings in annihilating bacteria by physical rapture, the research team married nature-based solutions with the intrinsic antimicrobial properties of copper to accelerate disinfection.
To synthesize the next-generation self-sanitizing surface, the researchers designed a scalable and cost-efficient chemical reaction that can be carried out at ambient conditions. The reaction initially produced sword-like copper nanostructures, but to the researchers’ surprise, the morphology of the surface evolved to take the form of foam when the reaction was prolonged. To satisfy their curiosity, they decided to put both versions of the nanostructured copper to the test.
The novel surfaces were extremely efficient in eliminating a wide range of microbes, from the common E. coli bacteria to viral surrogates for SARS-CoV-2 and even the antimicrobial-resistant ESKAPE pathogens that evolved from the overuse and misuse of antibiotics. While the sword-like nanostructured copper surface performed better than its foam-like counterpart, both of the novel surfaces are capable of destroying microbes within mere minutes, compared to conventional copper surfaces that take hours to do the job. Together with NCID and TTSH, the team is also exploring how these work on biofilm and surfaces which form part of the clinical environment.
“Our nature-inspired antimicrobial surface works much better due to the synergistic effect of nanostructures that facilitate quicker physical cell rupture and the rapid release of copper cations due to the larger contact area,” explained Zhang.
Having demonstrated the functionality of these nanostructured copper surfaces in laboratory-scale air purifiers, the team now aims to prototype their antimicrobial technology for commercialization, which shows great promise for applications in hospitals and other crowded areas – particularly relevant during these pandemic-stricken times that we live in.
The A*STAR researchers contributing to this research are from the Institute of Bioengineering and Bioimaging (IBB).
