3D-printed coral better than the real thing

Scientists have 3D printed coral-inspired structures they say are capable of growing dense populations of microscopic algae.

Writing in the journal Nature Communications, they report that in tests the structures grew a commercial strain of microalgae, Marinichlorella kaistiae, up to 100 times more densely than natural corals.

The potential, they believe, is two-fold: creating compact and efficient bioreactors for producing algae-based biofuels; and developing techniques to repair and restore coral reefs.

“Corals are one of the most efficient organisms at using, capturing and converting light to generate energy, and they do so in extreme environments, where light is highly fluctuating and there’s limited space to grow,” says first author Daniel Wangpraseurt, a marine scientist at the University of Cambridge, UK.

“Our goal here was to use corals as inspiration to develop more productive techniques for growing microalgae as a form of sustainable energy.”

Wangpraseurt teamed up with nanoengineer Shaochen Chen, whose lab at the University of California San Diego in the US can print structures with the speed needed to work with human, animal or algae cells.

The manufacture “corals” consist of cup-shaped, artificial skeletons that support coral-like tissue and are built to capture and scatter light more efficiently than natural corals. 

The skeleton is made of a biocompatible polymer gel, called PEGDA, embedded with cellulose nanocrystals. The coral tissue is 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. 

The researchers say nanocrystals embedded in the skeleton and coral tissue, along with the corals’ cup shape, improve light absorption and enable more light to be focused onto algae cells so that they photosynthesise more efficiently.