Researchers from the University of Cambridge and the University of San Diego created 3D printed coral-inspired structures that can grow dense populations of microscopic algae. This opens the door for coral conservation.

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

Coral provides a host for algae, which produces sugars for the coral via photosynthesis. This is responsible for the creation of the coral reef, one of the most diverse and productive ecosystems on Earth. Understanding coral decline is important to create future coral conservation strategies.

The team was searching for methods that copy and mimic coral reef strategies for commercial applications. To do this, they 3D printed intricate structures of natural coral using a rapid 3D bioprinting technique that uses light to print coral microstructures in seconds. This technique was originally used for bioprinting artificial liver cells. They also used optical coherence tomography to scan living corals to utilize as models for the designs.

Only biocompatible materials were used to create the 3D-printed bionic corals. The materials are a combination of polymer gels and hydrogels doped with cellulose nanomaterials that mimic the optical properties of the corals. Cellulose is an abundant polymer that is excellent at scattering light. In the 3D-printed coral, cellulose is used to optimize the delivery of light into photosynthetic algae.

Researchers tested various types of microalgae and found that their structure saw 100 times higher growth rates than the standard liquid growth mediums. These structures were used as incubators for algae growth. The structures were highly efficient at redistributing light just like natural corals.

The printed coral copies the structure and light-harvesting properties of natural coral. This creates an artificial host microenvironment for algae. Copying host microhabitats allows the 3D-bioprinted corals to be a model system for coral-algal symbiosis. This is needed to understand the breakdown of symbiosis during coral reef decline.

A paper on this technology was published in Nature Communications.