Functional imaging of 3D bioprinted microalgal constructs and simulation of their photosynthetic performance.

The intricate three dimensional architecture at different spatial length scales affects the functionality and growth performance of immobilized photosynthesizing cells in biofilms and bioprinted constructs. Despite the tremendous potential of 3D bioprinting in precisely defining sample heterogeneity and composition in spatial context, cell metabolism is mostly measured in media surrounding the constructs or by destructive sample analyses. The exploration and application of non-invasive techniques for monitoring physico-chemical microenvironments, growth and metabolic activity of cells in 3D printed constructs is thus in strong demand. Here, we present a pipeline for the fabrication of 3D bioprinted microalgal constructs with a functionalized gelatin methacryloyl (GelMA)-based bioink for imaging O2 dynamics within bioprinted constructs, as well as their characterization using various, non-invasive functional imaging techniques and numerical simulation of their photophysiological performance. This fabrication, imaging and simulation pipeline now enables investigation of the effect of structure and composition on photosynthetic efficiency of bioprinted constructs with microalgae or cyanobacteria. It can facilitate designing efficient construct geometries for enhanced light penetration and improved mass transfer of nutrients, CO2 or O2 between the 3D printed construct and the surrounding medium, thereby providing a mechanistic basis for the design of more efficient artificial photosynthetic systems.