Killing Bacteria in Seconds

A synthetic material that kills common bacteria in seconds could have far-reaching applications in healthcare and domestic settings

A*STAR researchers have developed a synthetic molecular complex capable of destroying common bacteria in seconds. Above are E.coli cells before (left) and after (right) treatment with the new material, which works by penetrating and destroying the cells’ membranes. © 2016 A*STAR Institute of Bioengineering and Nanotechnology

Killing bacteria quickly and efficiently is key to tackling the spread of infections, but the recent increase in drug-resistant bacteria has made this task particularly challenging. Now, A*STAR researchers have developed a synthetic molecule capable of killing bacteria such asE.coli in seconds, far more rapidly than any antimicrobial product, such as hand wash or surface spray, currently on the market1.

The challenge for scientists is to create antimicrobial agents that are capable of killing bacteria efficiently and effectively, yet safe for humans. Synthetic oligomers — tiny complexes that consist of a few selected molecules bound together — can be structurally engineered to exhibit certain behavior and have proven to be promising antimicrobial candidates.

“We’ve been working on novel antimicrobial materials for six years,” says Yugen Zhang at the A*STAR Institute of Bioengineering and Nanotechnology, who led the project in collaboration with scientists from Nanyang Technological University. “We had considerable success with our previous designs, but we wanted to further improve the speed at which our oligomers could destroy bacteria effectively.”

Based on prior designs, the team constructed seven new materials and tested their ability to destroy four common pathogens, including E.coli. Firstly, they tested the materials for safety on mammalian cells. They then trialed the oligomers’ antimicrobial activity, and analyzed how their different structures affected their performance in killing bacteria. The researchers identified one particular material, which exhibited superior efficacy compared to their other oligomer designs, and to existing antimicrobials.

“When I first saw the results from our material, I simply couldn’t believe it,” says Zhang. “It killed 99.7 per cent of E. coli in 30 seconds; an unprecedented result. We knew that the material’s physical properties played a significant role in these results, so we investigated how the oligomer interacted with the bacteria using computer-aided molecular simulations.”

The team created the material using positively-charged molecules linked together in a chain to attract negatively-charged bacteria cells. It has a unique structure with one ‘tail’ at each end of the chain, and they found that, once the bacterium is ‘caught’, these tails act like drills that penetrate and destroy the bacterial cell membranes. Once the cell membranes are ruptured, the bacteria die instantly.

Crucially, Zhang’s team also found that the oligomer is self-gelling in alcohol. This property will make the material easy to use in products such as hand wash and surface spray.

The A*STAR-affiliated researchers contributing to this research are from the Institute of Bioengineering and Nanotechnology