International. Studies have shown that the wings of dragonflies and cicadas prevent bacterial growth due to their natural structure. The surfaces of their wings are covered with nanopillars, which makes them look like a bed of nails. When bacteria come into contact with these surfaces, their cell membranes immediately tear apart and die.
This inspired researchers at the Institute of Bioengineering and Nanotechnology (IBN) at A*STAR Singapore to invent an antibacterial nanocoating for disinfecting frequently touched surfaces, such as door handles, tables and lifting buttons.
This technology will be especially useful for creating bacteria-free surfaces in places like hospitals and clinics, where sterilization is important to help control the spread of infections. Their new research was recently published in the journal Small.
"There is an urgent need for a better way to disinfect surfaces without causing bacterial resistance or damage to the environment. This will help us prevent the transmission of infectious diseases from contact with surfaces," said IBN Executive Director Professor Jackie Y. Ying.
A team of researchers led by IBN Group leader Dr. Yugen Zhang created a novel nano coating that can kill bacteria spontaneously on contact. Inspired by studies on dragonflies and cicadas, IBN scientists grew nanopilllars of zinc oxide, a compound known for its antibacterial and non-toxic properties. Zinc oxide nanopillars can kill a wide range of germs such as E. coli and S. aureus that are commonly transmitted by surface contact.
Tests on ceramic, glass, titanium and zinc surfaces showed that the coating effectively killed up to 99.9% of the germs found on the surfaces. As bacteria are killed mechanically rather than chemically, the use of the nano coating would not contribute to environmental pollution. In addition, bacteria will not be able to develop resistance, as they are completely destroyed when their cell walls are pierced by nanopillars on contact.
Other studies revealed that the nano coating demonstrated the best bacteria-killing power when applied to zinc surfaces, compared to other surfaces. This is because zinc oxide nanopillars catalyzed the release of superoxides (or reactive oxygen species), which could even kill nearby free floating bacteria that were not in direct contact with the surface.
This superbug-killer power from the combination of nanopillars and zinc extends the scope of coating applications beyond hard surfaces.
The researchers then studied the effect of placing a piece of zinc that had been coated with zinc oxide nanopillars in water containing E. coli. All the bacteria were killed, suggesting that this material could be used for water purification.
Dr Zhang said: "Our nano coating is designed to disinfect surfaces in a novel but practical way. This study showed that our coating can effectively kill germs on different types of surfaces and also in water."
"We were also able to achieve super bacteria-killing power when the coating was used on zinc surfaces due to its dual mechanism of action. We hope to use this technology to create bacteria-free surfaces in a safe, inexpensive and effective way, especially in places where germs tend to accumulate."
IBN recently received a grant from the National Research Foundation, Prime Minister's Office, Singapore, under its Competitive Research Programme to further develop this coating technology in collaboration with Tan Tock Seng Hospital for commercial application over the next 5 years.
Source: Institute of Bioengineering and Nanotechnology.
