When considering an octopus, one might envy its possession of eight limbs, each seemingly capable of accomplishing a multitude of tasks. However, scientists find a different fascination in these remarkable creatures – their skin.
Cephalopods, including octopi and squid, possess the astonishing ability to rapidly alter their skin color in response to various stimuli, such as threats or changes in light. This remarkable feature is attributed to the presence of xanthommatin, a naturally occurring dye within their bodies. At Northeastern University's Kostas Research Institute (KRI), dedicated researchers are delving into a synthesized version of this dye, with the aim of creating color-changing materials. Their most recent breakthrough involves the development of paint that transforms its hue when exposed to light.
KRI specializes in exploring intriguing components derived from natural sources and investigating how these components can be replicated and applied in practical contexts. Cephalopods have been an ideal starting point for their research due to the unique qualities of their skin.
Cassandra Martin, a research scientist at the institute, enthusiastically explains, “Their color change is so rapid and it's so vibrant and it's so intense. There's not a lot of natural systems out there that change that fast, and there's not a lot of color-changing materials that are that fast without requiring a lot of external triggers.”
KRI's dedicated team has long been working to replicate this remarkable natural phenomenon. In a previous endeavor, they developed wearable patches that change color when the wearer is exposed to excessive sunlight. However, they aspired to take it a step further and create a material with reversible color change capabilities.
Last summer, Kaitlyn Flynn, an intern and visiting student at the time, initiated a project involving this color-changing compound and decided to delve deeper. Collaborating with the team, they discovered that titanium dioxide acted as a conductor for the color change. By varying the proportions of titanium dioxide mixed with xanthommatin, they could control the speed and intensity of the color transformation.
These changes can manifest in as little as five minutes and persist for up to 24 hours, depending on the duration of light exposure. What's more, the colorant can be easily synthesized in as little as two hours and incorporated into both water and oil-based paints.
Their groundbreaking research was published in Advanced Science.
Dan Wilson, senior research scientist at the Kostas Research Institute, envisions the numerous possibilities for this innovation. “We've imagined a scenario where if you want to have art that changes from day to day on an interior wall, like maybe in a coffee shop, you could use a regular projector to project a pattern onto the wall, temporarily paint in this color and this pattern or this art, and then over time that fades away and you can redo it again, ideally as many times as you want. We can create temporary artwork or art or paint that could potentially track the weather or track the environment that it's in.”
Beyond the creative applications, this discovery carries significant environmental implications. It offers a sustainable alternative to the chemical-laden paints commonly found on the market.
Kaitlyn Flynn, now pursuing her Ph.D. in chemistry at Northeastern, emphasizes this point, stating, “Paints that are commercially used nowadays can have harmful chemicals in them, so they can have things that can be harmful to the people that are painting them. The fumes can be super harmful. They can be harmful long term if you're exposed to them for a long time. They can also leach out into the environment. Searching for a more natural way to make these paints creates a safer environment for the people using it and for the people that are going to be exposed to it.”
As they move forward, Kaitlyn Flynn and Cassandra Martin have ambitious plans. They aim to extend this color-changing system to other materials and broaden the color palette beyond the initial yellow-red range. Additionally, they aspire to give users the ability to control the speed at which the colors transform in the paint.
Source: Northeastern University