Speaker
Description
Objectives: Volumetric bioprinting (VBP) technologies have demonstrated unparalleled potential for printing centimeter-sized engineered tissues, with intricate architectures, in minutes. However, they still face limitations in scalability and resolution. Recently, a next-generation volumetric 3D printing technique named Xolography was introduced. Xolography operates by intersecting a UV-light sheet and a visible-light ultra-HD projection within a moving print-bath containing a dual-color photo-initiator (DCPI). This novel approach was shown to photoprint plastics at unprecedented volume generation rates (55 mm3.s−1) and resolution (<10 µm), while enhancing resin utilization efficiency and demonstrating promising scalability. However, its applications and associated processes have remained limited to the printing of plastics. In this work, we pioneered the bio-Xolographic printing of hydrogels to enable rapid high-resolution bioprinting of living matter.
Methods: Gelatin methacryloyl (GelMA) was blended with different photoreactive compounds to prepare multiple photopolymerizable formulations. Their reactivity was studied using dual-color photorheology and Xolography to identify optimal compositions for Xolographic 3D-printing of hydrogels. Parameters such as component concentration, printing speed, and light irradiance were optimized to achieve high-resolution printing. Cell-free hydrogels were printed in intricate shapes, and both printing fidelity and resolution were evaluated. To enable 3D-bioprinting, the cytotoxicity of DCPI, co-initiator, and different co-monomers was assessed to formulate bioinks that are non-cytotoxic and cell-conducive. Furthermore, cell-laden hydrogels (e.g., with human mesenchymal stromal cells, chondrocytes, and induced pluripotent stem cell-derived cardiomyocytes) were 3D-printed, and cell viability and function were determined. In addition, multimaterial printing, molecular patterning, and grayscale-mediated mechanical patterning are explored to programmably create intricate, biomimetic, and concentration-controlled architectures.
Results: The incorporation of diphenyliodonium chloride and N-vinylpyrrolidone proved essential for enabling Xolographic printing of hydrogels. These additives accelerated crosslinking speed, thereby addressing the reactivity limitations of existing DCPIs. Within 3 minutes, we successfully printed centimeter-scale structures with feature resolutions below 25 μm, as well as biologically relevant architectures containing perfusable interconnected channels. These results demonstrate that the high speed, resolution, and versatility of this emerging technology are translatable to hydrogel printing applications. DCPI maintained high cell viability (>98%) at concentrations suitable for 3D-printing. Moreover, 3D-bioprinted cell-laden hydrogels showed high resolution (<80 µm) and high post-crosslink cell viability (>80%). Repeated print cycles allowed for high resolution encoding of multimaterial designs and molecular patterns in a concentration controlled manner. Moreover, grayscale-mediated movie projection allowed for precise mechanical patterning by controlling crosslink density in a voxelized manner. Utilization of bioresins containing chondrocytes allowed for cartilage formation, while use of induced pluripotent stem cell-derived cardiomyocytes allowed for the biofabrication of electrically-induced contractile tissues. Together, this emphasizes the potential of bioxolography for the rapid biofabrication of large-scale functional tissues.
Conclusions: We here demonstrate that diphenyliodonium bioresin formulations based on chloride and N-vinylpyrrolidone enable Xolographic 3D-bioprinting of complex cm-scale living matter at high speeds and resolutions, while maintaining high cell viability. Bio-xolography is presented as a next generation technology for volumetric bioprinting of engineered tissues, with potential to bioprint and pattern large-sized multi-scale architectures within practical time windows.
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