Nanoparticles may damage bacterial cell walls, say scientists

By Katie Bird

- Last updated on GMT

Related tags Bacteria

Nanoparticles found in sunscreens may damage the cell walls of bacteria which could leave them unviable, according to recent research.

At the annual symposium of the American Chemical Society, scientists from the University of Toledo presented research illustrating the effect of nano titanium dioxide on bacteria.

According to Dr Cyndee Gruden, who conducted the research with Olga Mileyeva-Biebesheimer, even small amounts of the nanoparticles damaged the cell walls of the E. Coli​ bacteria.

Effects in environment unknown

However, the research has so far been confined to laboratory studies and as the environment is a much more complex system, it is difficult to predict what the wider effects may be, Gruden explained.

The nano titanium dioxide will find its way into water treatment plants when it is washed down the drain in consumers’ homes, but what effect it will have there remains unknown.

In addition, whether they are successfully removed from the waste water before it returns to the water system is unclear.

“The vast majority of metals end up in wastewater residuals due to their hydrophobic nature. However some small percentage may be discharged into the environment if they remain suspended in the effluent,”​ she told

Environmental and human safety

For Gruden, the work is a first step in attempting to answer some of the questions surrounding both the environmental and human safety of nanoparticles.

“When they enter a lake, what happens? Would they enter an organism or bind to it? Maybe they kill it — or have nothing to do with it at all. These are important questions for determining the effects that nanoparticles may have on the environment. Right now, we’re not really sure of the answers,”​ she said.

Further work is also needed to confirm the damaging effect to bacterial membranes is due to the nano size of the particles and not the compound itself.

Titanium is not known for its toxixcity and Gruden explained she would not expect to see the same extent of cell wall damage with non-nano titanium dioxide at these concentrations.

“Clearly, the control study must be done to conform the impact of the nano size,” ​she said.

The study was one of number of papers presented at the 273th ACS annual symposium where scientists were focusing on the environmental and human health effects of nanoparticles.

Related topics Formulation & Science

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