Scientists have genetically tweaked human cells to display the color-shifting, light-scattering characteristics seen in octopuses, squids, and other sneaky cephalopods. Invisible half-human, half-squid superheroes are unlikely to be in development anytime soon, but the new research does hold some real-world potential in the near future.
“For millennia, people have been fascinated by transparency and invisibility, which have inspired philosophical speculation, works of science fiction, and much academic research,” Atrouli Chatterjee, lead study author and doctoral student in chemical and biomolecular engineering at the University of California, Irvine (UCI), explained in a statement. “Our project – which is decidedly in the realm of science – centers on designing and engineering cellular systems and issues with controllable properties for transmitting, reflecting, and absorbing light.”
Reported in the journal Nature Communications this week, scientists led by the UCI took a few lessons from the opalescent inshore squid (Doryteuthis opalescens) and investigated the way they can change their appearance from white to brown when they’re hiding from a predator or depending on their mood. This species achieves this feat using specialized reflective cells called leucophores, which are composed of proteins known as reflectins that mirror back the colors of the surrounding environment. Depending on how the reflectins are arranged, they can alter how light is reflected off them, which creates the impression they are becoming invisible by reflecting the color of their surrounding environment.
The research team managed to use genetic engineering to introduce reflectins into the cytoplasm of human embryonic kidney cells in a petri dish. Once gazed at under a microscope, the human cells were shown to have this squid-like light scattering ability. They also managed to turn this effect on and off like a switch by using different concentrations of sodium chloride – higher levels of sodium resulted in higher degrees of light scattering and vice versa.
The researchers say their project raises the possibility of using reflectins as a new type of biomolecular marker for medical research and microscopy imaging.
“We were amazed to find that the cells not only expressed reflectin but also packaged the protein in spheroidal nanostructures and distributed them throughout the cells’ bodies,” Alon Gorodetsky, study co-author and UCI associate professor of chemical and biomolecular engineering.
“This project showed that it’s possible to develop human cells with stimuli-responsive optical properties inspired by leucophores in cephalopods, and it shows that these amazing reflectin proteins can maintain their properties in foreign cellular environments," they added.