This is a scanning electron microscope image of microalgal colonies in the hybrid living biopolymers. Image: University of Cambridge.
This is a scanning electron microscope image of microalgal colonies in the hybrid living biopolymers. Image: University of Cambridge.

Researchers from Cambridge University in the UK and the University of California, San Diego have 3D printed coral-inspired structures that are capable of growing dense populations of microscopic algae. Their results, reported in a paper in Nature Communications, open the door to new bio-inspired materials for applications in coral conservation.

In the ocean, corals and algae have an intricate symbiotic relationship. The coral provides a host for the algae, while the algae produce sugars for the coral through photosynthesis. This relationship is responsible for one of the most diverse and productive ecosystems on Earth: the coral reef.

"Corals are highly efficient at collecting and using light," said first author Daniel Wangpraseurt, a fellow in Cambridge's Department of Chemistry. "In our lab, we're looking for methods to copy and mimic these strategies from nature for commercial applications."

Together with colleagues, Wangpraseurt 3D printed coral structures and used them as incubators for algae growth. They tested various types of microalgae and found their growth rates were 100 times higher than in standard liquid growth mediums.

To replicate the intricate structures of natural corals, Wangpraseurt and his colleagues used a rapid 3D bioprinting technique originally developed for bioprinting artificial liver cells. They used purely biocompatible materials to fabricate the 3D-printed bionic corals, which proved highly efficient at redistributing light, just like natural corals.

"We 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," explained Silvia Vignolini from Cambridge University, who led the research. "Cellulose is an abundant biopolymer; it is excellent at scattering light and we used it to optimize delivery of light into photosynthetic algae."

The team used an optical analogue of ultrasound, called optical coherence tomography, to scan living corals and then utilized the resulting scans for their 3D-printed designs. The custom-made 3D bioprinter uses light to print coral micro-scale structures in seconds. The printed coral copies natural coral structures and light-harvesting properties, creating an artificial host-microenvironment for the living microalgae.

"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," said 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."

This story is adapted from material from Cambridge University, with editorial changes made by Materials Today. The views expressed in this article do not necessarily represent those of Elsevier. Link to original source.