Bioprinting bionic corals of the future

Bioprinting algae? How it all began...

In 2015, a group of researchers at the Institute of Food Technology and Bioprocess Engineering and the Center for Translational Bone, Joint and Soft Tissue Research at the Technische Universitat Dresden (TUD) in Germany introduced the idea of "Green Bioprinting". Using bioprinting, they immobilized microalgae in hydrogels made of alginate and methylcellulose, and demonstrated that they were able to achieve stable growth, in contrast to suspension cultures that were dependent on temperature and illumination conditions. Practical applications of this work would include bioproduction of photosynthetic microorganisms for renewable energy, chemicals or pharmaceutical drugs. To learn about this work - read more.

Today...

Fast forward 5 years later, a group of researchers from UC San Diego and University of Cambridge showed how microalgae can be bioprinted to create bionic corals of the future - read more. By using a very unique approach, this group was able to create a hybrid photosynthetic biomaterial scaffold that uniquely re-created a microenvironment that is optimal for microalgae growth. 3D printing and bioprinting enabled them to create both the structural and functional aspects of the coral-algal symbiosis, enabling microalgae to achieve high spatial densities of up to 1 billion cells/mL.

What makes them different?

In studying the photosynthetic efficiency of coral-algae symbiosis, this group discovered that space efficient light management in corals could be used to overcome the problem of algal self-shading which is limiting the upscaling of microalgal cultivation. By utilizing a 2-step continuous light-projection based approach, the researchers were able to create precise scattering properties of the artificial coral scaffold. A combination of materials including a photosensitive hydrogel (gelatin-methacrylate - GelMA), polyethylene glycol diacrylate-based polymer (PEGDA) and cellulose-derived nanocrystals (CNC) were used to achieve the desired optical and mechanical properties of the photosynthetic scaffold. Check out this open access Nature Communications paper and see the cool electron microscopy and fluorescence images.

Looking ahead

The unique approach made by this group will certainly inspire others to look more closely at coral-algae symbiosis and the development of synthetic model systems for improving algae bioproduction. One limitation that we will need to overcome is scale up of bioprinting techniques and platforms to create larger constructs at the scale of photobioreactors. Perhaps a good discussion topic for the next blog!

Cool ideas | Easy projects

Inspired by the very first article, our previous group at SE3D had explored cool and fun projects to bioprint with microalgae. One idea we had was to see how we can use microalgae to create beautiful 3D algae plant structures for the home as an eco-friendly and low maintenance solution for those of us who do not have "a green thumb".


Around Xmas time, we thought about printing a microalgae Christmas tree starting from the first day of December and allowing algae to grow over time until you get a "green" Christmas tree packed with algae by December 25th. Even cooler - how about printing these with bioluminescent algae and create artificial "lava" algae lamps for your bedside stand?

Our Little Experiment

We have also experimented with 2 different concentrations of alginate-methylcellulose mixture and performed degradation studies over time to evaluate printability and structural integrity for microalgae in long-term culture up to 3-4 weeks. Some images taken from this experiment include: cylindrical scaffolds printed with 6% and 9% methylcellulose (MC) and 1% alginate solution, a spike-like shaped cylinder printed in 9% MC | 1% alginate and picture during printing process.


Observations made from this experiment included the printability of 9% MC hydrogels compared to 6% MC counterparts. On the same token, degradation in the integrity of the overall shape was more apparent in the 6% MC hydrogels as compared to the 9% MC hydrogels. Maximum growth was achieved in about 7-8 days and no apparent differences were made after 2 weeks.

Printing of alginate-methylcellulose hydrogels can be achieved using any extrusion based bioprinter. After printing, a simple cross-linking step can be performed by adding calcium chloride solution for 5-10 minutes to allow hydrogel to "solidify" and culture algae in appropriate medium per supplier  recommendations.

Good luck and have lots of fun printing algae!

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