Chameleon cages
Biologists have created a "biohybrid" material with heart cells, alive and beating
Sergey Vasiliev, Naked Science
The dyes-pigments familiar to us give color by reflecting optical waves of a certain length and absorbing the rest. In contrast, structural coloration is created not by individual molecules, but by microscopic elements of a complex surface. This is how the wings of a butterfly or the tail of a peacock are painted. The same effect gives bright colors to the "biohybrid" material, which was developed by scientists at the Southeastern University in Nanjing, China.
Yuanjin Zhao and his co-authors spied the idea for their work from another natural "metamaterial", which reports a changeable color to the chameleon skin. It contains a lot of tiny crystals, and the animal can adjust the distance between them, then bringing them closer, then spreading, while changing the wavelength that is reflected and creates the color of this area of the skin.
In an article published in the journal Science Robotics (Fu et al., Bioinspired living structural color hydrogels), scientists described a similar artificial system. To do this, they used a matrix of biocompatible hydrogel, the pores of which are filled with light-reflecting nanoparticles. On this basis, a cell culture of rat cardiac muscle cells (cardiomyocytes) was grown. Synchronous cell contractions deformed a thin strip of gel, changing the location of nanoparticles and forcing the material to move from one structural color to another.
It is worth noting that the new work is interesting not only with a beautiful picture. Such a "biohybrid" material allows you to accurately and visually visualize the work of contracting cells and, perhaps, in the future, will facilitate many scientific experiments, the study and creation of new drugs. This possibility was pointed out by the authors themselves, demonstrating how the rhythm of contractions of their material is accelerated by the addition of isoprenaline, the active ingredient of many popular cardiovascular drugs.
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