Droplet bioprinting of acellular and cell-laden structures at high-resolutions

• Published in: Biofabrication 2024-07, Vol.16 (3), p.35019
• Main Authors: Kunwar, Puskal, Aryal, Ujjwal, Poudel, Arun, Fougnier, Daniel, Geffert, Zachary J, Xie, Rui, Li, Zhen, Soman, Pranav
• Format: Article
• Language: English
• Subjects: Animals; bioink; bioprinting; Bioprinting - methods; Cell Survival; DLP; Droplet; Humans; Ink; low-volume; Mice; Printing, Three-Dimensional; Tissue Engineering - methods; Tissue Scaffolds - chemistry; vat-free; Viscosity; Wettability
• ISSN: 1758-5082; 1758-5090; 1758-5090
• DOI: 10.1088/1758-5090/ad4c09

Advances in digital light projection(DLP) based (bio) printers have made printing of intricate structures at high resolution possible using a wide range of photosensitive bioinks. A typical setup of a DLP bioprinter includes a vat or reservoir filled with liquid bioink, which presents challenges in terms of cost associated with bioink synthesis, high waste, and gravity-induced cell settling, contaminations, or variation in bioink viscosity during the printing process. Here, we report a vat-free, low-volume, waste-free droplet bioprinting method capable of rapidly printing 3D soft structures at high resolution using model bioinks and model cells. A multiphase many-body dissipative particle dynamics model was developed to simulate the dynamic process of droplet-based DLP printing and elucidate the roles of surface wettability and bioink viscosity. Process variables such as light intensity, photo-initiator concentration, and bioink formulations were optimized to print 3D soft structures (∼0.4-3 kPa) with a typical layer thickness of 50 m, an XY resolution of 38 ± 1.5 m and Z resolution of 237 ± 5.4 m. To demonstrate its versatility, droplet bioprinting was used to print a range of acellular 3D structures such as a lattice cube, a Mayan pyramid, a heart-shaped structure, and a microfluidic chip with endothelialized channels. Droplet bioprinting, performed using model C3H/10T1/2 cells, exhibited high viability (90%) and cell spreading. Additionally, microfluidic devices with internal channel networks lined with endothelial cells showed robust monolayer formation while osteoblast-laden constructs showed mineral deposition upon osteogenic induction. Overall, droplet bioprinting could be a low-cost, no-waste, easy-to-use, method to make customized bioprinted constructs for a range of biomedical applications.