Tipping the Scales

The vibrant orange of a toucan’s beak. The emerald green of a turtle’s shell. The striking red of a field of tulips. Nature is full of stunning examples of mesmerizing color and beauty – as they say, “nature does it best.” Attempts to mimic these tones is an active area of research, gifting today’s scientists with an ever-growing library of synthetic compounds for application in food, beverages, paint, cosmetics and beyond.

But, as the high-carbon footprint (and toxicity) of many of these pigments becomes more apparent, the demand for more environmentally friendly alternatives grows stronger. Did you know that titanium dioxide – prized for its whiteness – contributes almost 75 percent of a paint can’s carbon footprint?

Inspired by such revelations, Andrew Parnell and colleagues set out to find an alternative (1). The Cyphochilus beetle, noted for its opaque, white scales, has proven an unusual specimen; its color can be attributed to light scattering (where refraction and reflection of light inside the scale is responsible for its color, shade, tone, and hue) rather than the result of color pigments.

To avoid damaging the beetle’s delicate scales, the team used X-ray nanotomography – a non-invasive approach – to study the three-dimensional nanostructure. “The first thing we noticed was that the structure was continuous,” says lead author Stephanie Burg. From there, the team generated two hypotheses: firstly, that the structure was likely established at a single point in time during the beetle’s development; and secondly, that this process might be easily replicated and reproduced.