A team of scientists at the University of Hull have developed a new family of selective antimicrobial agents which could hold the key to fighting microbes without the use of traditional antibiotics.
Their report on these synthetic colloid particles, which can be custom-designed to recognise the shape of specific kinds of microbes and 'de-activate' them, appears in the Journal of the American Chemical Society.
The team, led by Dr Vesselin Paunov of the University's Faculty of Science and Engineering, point out that many common microbes have developed resistance to existing antibiotics. It seems that whatever drugs the pharmaceutical industry designs to attack them, microbes soon find ways to adapt and become resistant to them.
They came up with a new approach - one that microbial cells would find harder to evade. The scientists' inspiration was the antibodies that the immune system itself produces when microbes invade the body. Those antibodies patrol the body for microbes and bind to their surfaces, "marking" them for destruction by the body's immune system which attacks and destroys the microbes.
Paunov's research team developed specially-engineered colloid particles, which they called 'colloid antibodies'. Colloids consist of very small particles of one material that are dispersed in another material. To prove the concept, the team used the target cells as templates and produced silica shells with gold nanoparticles on their surface. When fragmented and removed from the target cells, these colloidal shell fragments retained the shape of the templated cells and were able to recognize and bind cells with the same shape and size.
The scientists incubated them with a mixture of microbes of different shapes. The shape-recognising "microscopic casts" were able to bind selectively to the target microbes and bring gold nanoparticles directly on their surface. When the team illuminated the mixture with a laser, the gold nanoparticles absorb light and heat up only the target microbes which causes their death, while leaving the other cells unscathed.
Dr Paunov said: "We anticipate that similar shape-selective colloid antibodies can potentially become a powerful weapon in the fight against antibiotic-resistant bacteria. Colloid antibodies combined with other cell-killing strategies could also have applications as selective antimicrobial agents, preventing growth of pathogenic microbes in various formulations."
In the future, the team will focus on developing colloid antibodies for specific bacteria and will probe how a similar strategy may work for de-activation of some viruses.
The researchers' project was assisted by funding from the BBSRC.
Notes to editors
The paper: 'Photothermal Colloid Antibodies for Shape-Selective Recognition and Killing of Microorganisms' is available at: pubs.acs.org/doi/abs/10.1021/ja400781f.