Coral-Inspired Biomaterials Could Lead to Highly Efficient Biofuel Production

Researchers at the Scripps Institution of Oceanography and Jacobs School of Engineering at UC San Diego, and the University of Cambridge, U.K., have 3D printed coral-inspired structures that are capable of growing dense populations of microscopic algae. The work, published April 9 in Nature Communications, could lead to the development of compact, more efficient bioreactors for producing algae-based biofuels. It could also help researchers better understand the intricate biology of the coral-algae relationship, and develop new techniques to repair and restore coral reefs.

In laboratory test settings, the printed coral structures were used as a platform to grow two different types of microalgae, which rapidly grew to achieve up to 100 times greater density than in liquid cultures. The species were Marinichlorella kaistiae, which has commercial potential, and Symbiodinium sp., the type of algae that populates corals in the wild.  

“Corals are one of the most efficient organisms at using, capturing, and converting light to generate energy,” said author Daniel Wangpraseurt, a former Marie Curie postdoctoral fellow between Scripps Oceanography and the University of Cambridge who completed the work while at Scripps. “And they do so in extreme environments, where light is highly fluctuating and there’s limited space to grow. Our goal here was to use corals as inspiration to develop more productive techniques for growing microalgae as a form of sustainable energy.” 

To build the coral structures, Wangpraseurt organized a team of scientists at Scripps and UC San Diego, including: former advisor Dimitri Deheyn, associate researcher at Scripps who was his primary advisor; Farooq Azam, professor of marine microbiology at Scripps; the late Mark Hildebrand, research molecular biologist at Scripps, along with his former PhD student Olga Gaidarenko; and nanoengineering professor Shaochen Chen in the Jacobs School of Engineering.

Wangpraseurt worked with the team from Scripps to measure the photosynthetic activity of the corals in both liquid cultures and in the coral models. They also looked at how the algae grew on the structures, and ways in which to maximize the growth on these mimic corals. The structures themselves were developed with Chen, whose lab specializes in a rapid 3D bioprinting technology capable of reproducing detailed structures that mimic the complex designs and functions of living tissues. Chen’s method can print structures with micrometer-scale resolution in just minutes.

The 3D printed corals are built to capture and scatter light more efficiently than natural corals. They consist of cup-shaped, artificial skeletons that support coral-like tissue. The skeleton is made up of a biocompatible polymer gel, called PEGDA, embedded with cellulose nanocrystals. The coral tissue consists of a gelatin-based polymer hydrogel, called GelMA, mixed with living algae cells and cellulose nanocrystals.

On the surface are tiny cylindrical structures that act as coral tentacles, which increase the surface area for absorbing light. Nanocrystals embedded in the skeleton and coral tissue, along with the corals’ cup shape, also improve light absorption and enable more light to be focused onto algal cells so that they photosynthesize more efficiently.

“The original goal was to develop a platform that mimicked real corals in order to optimize growth of algae that are critical for biofuels,” said Deheyn. “What we came to realize is that bionic corals already had superior productivities compared to current systems. It is clear that the doors are now wide open to use this novel research tool to better understand how corals work so that we can design better strategies for sustainable coral restoration.” 

This study was funded by the European Union’s Horizon 2020 research and innovation programme, the European Research Council, the David Phillips Fellowship, the National Institutes of Health, the National Science Foundation, the Carlsberg Foundation and the Villum Foundation.

This release was adapted from the Jacobs School of Engineering at UC San Diego.

 

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