A Universal Strategy to Construct High‐Performance Homo‐ and Heterogeneous Microgel Assembly Bioinks

Abstract Three dimensional (3D) extrusion bioprinting aims to replicate the complex architectures and functions of natural tissues and organs. However, the conventional hydrogel and new‐emerging microgel bioinks are both difficult in achieving simultaneously high shape‐fidelity and good maintenance of cell viability/function, leading to limited amount of qualified hydrogel/microgel bioinks. Herein, a universal strategy is reported to construct high‐performance microgel assembly (MA) bioinks by using epigallocatechin gallate‐modified hyaluronic acid (HA‐EGCG) as coating agent and phenylboronic acid grafted hyaluronic acid (HA‐PBA) as assembling agent. HA‐EGCG can spontaneously form uniform coating on the microgel surface via mussel‐inspired chemistry, while HA‐PBA quickly forms dynamic phenylborate bonds with HA‐EGCG, conferring the as‐prepared MA bioinks with excellent rheological properties, self‐healing, and tissue‐adhesion. More importantly, this strategy is applicable to various microgel materials, enabling the preparation of homo‐ and heterogeneous MA (homo‐MA and hetero‐MA) bioinks and the hierarchical printing of complicated structures with high fidelity by integration of different microgels containing multiple materials/cells in spatial and compositional levels. It further demonstrates the printing of breast cancer organoid in vitro using homo‐MA and hetero‐MA bioinks and its preliminary application for drug testing. This universal strategy offers a new solution to construct high‐performance bioinks for extrusion bioprinting.