Nature lights way to new paints and cosmetics

A plant-like microorganism mostly found in oceans could make the manufacture of products such as iridescent cosmetics, paints and fabrics, and credit-card holograms much cheaper and greener, according to scientists in Britain.

The tiny single-celled diatom, which evolved hundreds of millions of years ago, has a hard silica shell that is iridescent. This effect is caused by a complex network of tiny holes in the shell that interferes with light waves.

Scientists at the Natural History Museum and the University of Oxford have found an effective way of growing diatoms in controlled laboratory conditions, with potential for scale-up to industrial level.

This would enable diatom shells to be mass-produced, harvested and mixed into paints, cosmetics and clothing to create colour-changing effects, or embedded into polymers to produce difficult-to-forge holograms.

Manufacturing consumer products with these properties currently requires energy-intensive, high-temperature, high-pressure industrial processes that create tiny artificial reflectors.

But farming diatom shells could provide an alternative that takes place at normal room temperature and pressure, reducing energy needs and cutting carbon-dioxide emissions. The process is also rapid — in the right conditions, one diatom can give rise to 100 million descendants in a month.

“It is a very efficient and cost-effective process, with a low carbon footprint,” said Professor Andrew Parker, who led the research.

“Its simplicity and its economic and environmental benefits could in future encourage industry to develop a much wider range of exciting products that change colour as they or the observer move position. Furthermore, the shells are completely biodegradable, aiding eventual disposal and further reducing the environmental impact of the process life cycle.”

The researchers estimate that up to one tonne a day of diatoms could be produced in the laboratory in this way, starting from just a few cells. An industrial-scale process could be operational within two years.