We’ve seen several projects initiated across the globe to 3D print coral-like structures to preserve threatened underwater ecosystems. In most, the artificial coral reefs are designed to encourage the growth of natural coral and provide shelter to many of the underwater species that live in the delicate environment. A recent project coming out of Cambridge University and the University of California San Diego, however, is taking 3D printed coral to another level: the joint research team has developed 3D bioprinted coral-like structures that are actually capable of growing microscopic algae.
Coral and algae are closely tied and exist in symbiosis in the ocean. In short, the coral provides a host for the algae, while algae organisms produce sugars for the coral through photosynthesis. Together, coral and algae have formed the foundation for coral reef ecosystems, which are some of the most diverse and productive on the planet.
“Corals are highly efficient at collecting and using light,” explained Dr. Daniel Wangpraseurt, a Marie Curie Fellow from Cambridge’s Department of Chemistry and first author of a study published in Nature Communications. “In our lab, we’re looking for methods to copy and mimic these strategies from nature for commercial applications.”
In their work, the researchers have developed 3D printed coral structures using a rapid bioprinting technique. According to the team, this technology has enabled it to produce complex, coral-like geometries with micrometer-scale resolution in mere minutes. The 3D printed coral is used as an incubator for algae cells, enabling the algae to grow and thrive at much higher rates (about 100x) than using standard liquid growth mediums.
UC San Diego’s Professor Shaochen Chen, co-senior author, specified why bioprinting was used in lieu of other AM processes: “Most of these cells will die if we were to use traditional extrusion-based or inkjet processes because these methods take hours. It would be like keeping a fish out of the water; the cells that we work with won’t survive if kept too long out of their culture media. Our process is high throughput and offers really fast printing speeds, so it’s compatible with human cells, animal cells, and even algae cells in this case.”
The bioprinted coral is made from a combination of biocompatible polymer gels and hydrogels which are infused with cellulose nanomaterials that effectively mimic the optical properties of healthy coral. Cellulose plays an important role in the structure, as it helps to scatter light and promotes photosynthesis in the algae. In tests, the bioprinted coral proved to be highly efficient at distributing light. The structure of the printed coral was designed by scanning living coral using optical coherence tomography. The 3D scan was used as a basis to create the 3D printed coral structure.
Interestingly, the bioprinted coral will not have exactly the same applications as other 3D printed coral we’ve seen, which are made from materials like ceramic and placed into aquatic habitats to imitate the protective function of coral. Rather, the bioprinted coral-like structures can be used to cultivate algae for bioproducts, helping to improve sustainable practices and reduce emissions.
“By copying the host microhabitat, we can also use our 3D bioprinted corals as a model system for the coral-algal symbiosis, which is urgently needed to understand the breakdown of the symbiosis during coral reef decline,” added Wangpraseurt. “There are many different applications for our new technology. We have recently created a company, called mantaz, that uses coral-inspired light-harvesting approaches to cultivate algae for bioproducts in developing countries. We hope that our technique will be scalable so it can have a real impact on the algal biosector and ultimately reduce greenhouse gas emissions that are responsible for coral reef death.”
The innovative and eco-focused project is funded by the European Union’s Horizon 2020 research and innovation program, as well as the European Research Council, David Phillips Fellowship, the National Institutes of Health, the National Science Foundation, the Carlsberg Foundation and the Villum Foundation. Ultimately, the joint team of researchers hope their work will create opportunities for bio-inspired materials and coral conservation.