Microalgae as bioinks for 3D laser printing

Microalgae such as the diatom Odontella aurita and the green alga Tetraselmis striata are particularly suitable as "biofactories" for sustainable materials in 3D laser printing, as they are rich in fats and photoactive dyes. An international research team led by Heidelberg University has used raw materials from these microalgae for the first time to develop inks for special applications in 3D printing.

The team, led by Prof. Dr. Eva Blasco from the Institute for Molecular Systems Engineering and Advanced Materials (IMSEAM) at Heidelberg University, says it has succeeded in developing special inks from microalgae raw materials. According to the scientists, these are ideal for printing complex biocompatible 3D microstructures. In the future, these microalgae-based materials could also serve as the basis for implants or scaffolds in 3D cell culture.

Manufacturing advantages for micro- and nanostructures

3D laser printing with two-photon polymerization offers particular advantages in additive manufacturing for the production of micro- and nanostructures. Thanks to its high resolution, it is used in areas such as optics, photonics, microfluidics and biomedicine. A focused laser beam is directed at a liquid, photoreactive coating, the "ink". The photoactive green dyes present in the microalgae proved to be excellent photoinitiators. Under the influence of the laser beam, they trigger the chemical reaction that solidifies the ink into a three-dimensional structure.

Until now, this precise 3D laser printing has mainly used petrochemical-based polymers, which are based on fossil fuels, release greenhouse gases and can contain potentially toxic components. In contrast, microalgae offer a sustainable alternative as they grow quickly, bind carbon dioxide and are biocompatible. "This allows us to avoid the use of potentially toxic additives such as photoinitiators, which are used in conventional inks. Despite their advantages, microalgae have hardly ever been considered as raw materials for light-based 3D printing," explains Blasco. Her research group at Heidelberg University is working at the interface of macromolecular chemistry, materials science and 3D nanofabrication to tap into this potential.

Using the new ink system, the scientists were able to create precise 3D microstructures with complex features such as overhanging roofs and cavities. They tested the biocompatibility of the microalgae-based inks through experiments with cell cultures, in which three-dimensional micro-scaffolds were created on which the cells were cultivated for around 24 hours. The survival rate of the cultures was almost 100 percent. "Our results not only open up new possibilities for more sustainable 3D printing with light, but also for life science applications - from three-dimensional cell cultures to biocompatible implants," explained Blasco.

The research work was part of the "3D Matter Made to Order" Cluster of Excellence, a collaboration between Heidelberg University and the Karlsruhe Institute of Technology (KIT). In addition to the Heidelberg scientists, researchers from KIT and the Banco Español de Algas at the Universidad de Las Palmas de Gran Canaria (ULPGC, Spain) were also involved. The project was funded by the German Research Foundation, the Carl Zeiss Foundation, the Chemical Industry Fund and the European Union as part of the European Territorial Cooperation Program. The results were published in the journal Advanced Materials.

(anw)