Advancing 3D-Bioprinting with Photopolymerization of Orderly Extruded Multi-Materials (POEM)

Printing functional tissues and organs on demand is a major goal in biofabrication. However, replicating intricate structures resembling cellular arrangements and physical characteristics of human tissues and organs remains the greatest challenge. Up to date, several systems, such as extrusion and light-based bioprinting techniques, have been widely studied. Achieving desired realistic, high-resolution 3D features on multi-material and multi-layer complex structures while simultaneously incorporating cells and maintaining high cell viability is the holy grail of bioprinting and remains to be achieved. Addressing this limitation, we proposed, developed, and fully characterized a novel 3D-bioprinting technique called photopolymerization of orderly extruded multi-materials (POEM). The proposed technique operates by infusing temporarily viscous photo-cross-linkable bioinks layer-by-layer. It is subsequently followed by precise and high-resolution photopatterning of the layers to the desired shapes and configurations. The proposed POEM technique offers a single-step photopolymerization that eliminates the requirement for multiple processing steps, interim cleaning processes, or material exchange throughout the multi-material/multi-layer printing procedure. This also eliminates cross-contamination and the loss of valuable cells and inks during the cleaning process. Herein, we demonstrate the utility of the POEM technique for rapid and high-resolution 3D printing of multi-material, multi-layer, and cell-laden structures. The printed configurations exhibit remarkable cell viability (approximately 80%) and metabolic activity for over 5 days. As proof of concept, we successfully fabricated and characterized a 3D structure representing the esophagus. The development of POEM represents a significant advancement in 3D-bioprinting technology, offering new possibilities for constructing physiologically relevant tissue constructs.