Granular Biphasic Colloidal Hydrogels for 3D Bioprinting

Abstract

Granular hydrogels composed of hydrogel microparticles are promising candidates for 3D bioprinting due to their ability to protect encapsulated cells. However, to achieve high print fidelity, hydrogel microparticles need to jam to exhibit shear‐thinning characteristics, which is crucial for 3D printing. Unfortunately, this overpacking can significantly impact cell viability, thereby negating the primary advantage of using hydrogel microparticles to shield cells from shear forces. To overcome this challenge, we introduce a novel solution: a biphasic, granular colloidal bioink designed to optimize cell viability and printing fidelity. The biphasic ink consists of cell‐laden polyethylene glycol (PEG) hydrogel microparticles embedded in a continuous gelatin methacryloyl (GelMA)‐nanosilicate colloidal network. Here, we demonstrate that this biphasic bioink offers outstanding rheological properties, print fidelity, and structural stability. Furthermore, we demonstrate its utility for engineering complex tissues with multiple cell types and heterogeneous microenvironments, which we demonstrate by incorporating β‐islet cells into the PEG microparticles and endothelial cells in the GelMA‐nanosilicate colloidal network. Using this approach, it is possible to induce cell patterning, enhance vascularization, and direct cellular function. The proposed biphasic bioink holds significant potential for numerous emerging biomedical applications, including tissue engineering and disease modeling.This article is protected by copyright. All rights reserved