3D-printed ‘bionic corals’ mimic a reef’s powers of photosynthesis
The massive death of coral reefs is a catastrophe of global dimensions, but the scale of their success as organisms has lessons for science. Concrete example: these “bionic corals” 3D printed by Cambridge researchers which are more than scaffolding for fragile microorganisms – they are built from them.
If 3D-printed corals seem familiar to you, it’s because a few years ago, other researchers suggested using printed structures to resemble the complex shapes of reefs as solid bases on which new corals and other animals may develop. It’s a good idea, but there is more to a reef than a solid foundation.
Corals are in fact a highly evolved symbiosis between the coral organisms themselves and the algae that live there. Algae use photosynthesis to fuel the creation of sugar for their host, and coral provides a safe living environment – and, interestingly, is also very effective at collecting and redirecting light. This partnership has been successful for millions of years, although rising ocean temperatures and acidity have upset the delicate balance necessary for success.
The Cambridge team realized that to successfully mimic the coral micro-ecosystem, they had to reproduce this special quality of sun capture and diffusion indoors for use by resident algae. To do this, they closely studied the structure of the corals and worked to remake it at the microscopic level. But instead of using an ordinary durable substrate, they created a kind of living gel.
“We have developed an artificial coral tissue and skeleton with a combination of polymer gels and hydrogels doped with cellulose nanomaterials to mimic the optical properties of living corals,” said Cambridge chemist Daniel Wangpraseurt, lead author of the paper in which the technique is described. The algae were also infused into the mixture, so the researchers were essentially printing living matter.
This type of technology is already tested and used for medical purposes – the printing of part of an organ or tissue for implantation, for example. In this case, it should be printed not with a specific shape on a large scale, but with an extremely complex internal geometry which maximizes the range of light striking the surface. This must be done very quickly or the algae will die from the exposure.
The resulting bio-printed structure is an ideal home for algae, producing growth rates several times greater than the speed of an ordinary medium. This does not mean that the next step is to grow corals very quickly – in fact, there is no reason to think that it will actually lead to the restoration of corals. On the other hand, this type of simulation could lead to a better understanding of the ecosystem in which the coral-algae partnership develops and how it can be nourished.
Meanwhile, the promise of increasing algae growth rates has commercial appeal today, and a startup called Mantaz was founded to pursue shorter-term uses of the technology.