The next time you need to freshen up the paint on your house or apply a bit of cosmetic glitter before heading out for the night, you might want to give a quick nod to the butterflies fluttering in a nearby garden. Taking inspiration from structures on those wings that make their vibrant colors, researchers are now devising more durable and adjustable colors that are also safer for human health and the environment.
The researchers will present their results at the fall meeting of the American Chemical Society (ACS) during the "Carbon-based Nanomaterials: From Fundamental Insights to Applications" symposium in McCormick Place. ACS Fall 2026 is being held August 23-27.
Because structural color arises from the physical architecture of the material rather than light absorption by a biomolecule, it does not fade over time." - Leila Deravi.
In nature, the chemical structure of some molecules causes them to absorb specific wavelengths of light, reflecting the rest, and it is the reflected light that we perceive as pigmentary color. This is what makes carrots orange (carotenoids), blood red (hemoglobin), and plants green (chlorophyll).
As pigmentary colors are exposed to sunlight and other environmental elements, however, the chemical compounds can break down and the colors fade, requiring a refresh. Additionally, many commercial dye and pigment formulas contain toxic chemicals - or may themselves be toxic.
Nature also produces what are known as structural colors resulting from the physical arrangement (e.g., crystal structures) of molecules. These microscopic formations bend, scatter, and interfere with specific wavelengths of light, so that we only see the reflected wavelengths. Structural colors are what cause the rainbow of opal gemstones, the blues and greens of peacock feathers, and the deep blue of morpho butterfly wings.
"Structural color materials offer two key advantages over most traditional, pigment-based products: durability and vibrancy," says Leila Deravi, the principal investigator of this study. "Because structural color arises from the physical architecture of the material rather than light absorption by a biomolecule, it does not fade over time."
Clara Wen Dou / Northeastern University / Boston Electron Microscopy Center
Trying to understand how chemical composition and crystal structure influence color generation, Deravi, Associate Professor of Chemistry and Chemical Biology, and her colleagues at Northeastern University studied butterflies in the Pieridae family, such as the Cabbage White and Clouded Sulfur varieties commonly found in open meadows. The researchers will present their findings on pterins, compounds that are related to those that make up DNA and found on the surface of butterfly wings.
Deravi suggests color intensity could be adjusted by controlling the size and packing of the pterin crystals rather than requiring many different pigments. There might also be safety advantages because these natural biomolecules are already being produced and used by animals and plants.
"They're safe for the environment," Deravi continues. "They're safe for people, and they don't have a lot of downstream toxicity like some of the forever chemicals used in synthetic pigmentary dyes."
The researchers are quick to note, however, that they have not yet initiated studies to validate pterin safety.
Critical to studying structural colors from pterins, however, is the need to produce and modify pterin crystals in the lab, the focus of Clara Dou, a graduate student in Deravi's lab and presenter of their work at the meeting. To do this, she synthesized pterin granules that mimic the structures on butterfly wings.
Northeastern University
As Dou explains, forming the microscopic crystals out of pterins has historically required organic solvents such as dimethyl sulfoxide (DMSO), chemicals that can present safety concerns for human health and the environment. And crystallization using DMSO takes several weeks to complete.
"If the animals can do this without DMSO, how can we replicate this natural process in the lab?" Dou asks.
"Our work addresses this by exploring how water, salt, and acidity influence crystallization," she continues. Using the new method, Dou can get crystals to precipitate out of solution and isolate them in a matter of minutes. The researchers can then see how changing crystal growth conditions change the reflected color.
The team's new process reduces the need for organic solvents, making it more environmentally friendly than the currently used methods.
Although the current work produces only milligram-size (like grains of table salt) amounts of structural colors, the researchers are currently scaling up production as they believe it has commercial potential. They say these pterin structural colors could be a natural and sustainable source that overcomes some of the toxicity concerns associated with, for example, the metal oxides used in products such as cosmetic glitter.
"If we can make some templates for glitter using essentially derivatives of DNA, that would be incredible," Deravi says.
"Ultimately, there's still a great deal left to learn about biological color," she continues. "It's something we all interact with daily in the flowers, insects, and animals around us, yet the underlying mechanisms behind their long-lived, fade-resistant color are still being defined."
The research was funded in part by Northeastern University.
