Lubricating Micro-Interface Assisted General Strategy for Preparing dECM-Microparticle–Based Heterogeneous Granular Inks toward 3D Printing

Decellularized extracellular matrix (dECM) retains the bioactive components to mimic tissue-specific microenvironment. Designing dECM-based inks for 3D printing to prepare scaffolds can enhance the regeneration of corresponding tissues. However, due to the strict requirements for inks, how to efficiently prepare dECM-based inks is a challenge. Inspired by granular lubrication, the present study proposes an effective and general method for preparing granular ink from dECM microparticles (MP) with high content. Through dopamine polymerization, dECM-MPs are coated with polydopamine (PDA). Meanwhile, gelatin methacryloyl (GelMA)-based microspheres (GelMA-MSs) are prepared with available double bonds. dECM-MPs (30–40 wt%) and GelMA-MSs assemble to form a granular ink, exhibiting well-performed extrudability, plasticity, and fidelity. Further inspired by joint lubrication, hyaluronic acid (HA) is introduced into PDA coating and GelMA-MSs to reduce the micro-interface friction, further promoting the printability and broadening the printable window of dECM-MPs content to 30–60 wt%. Osteochondral scaffold and skin wound dressing are fabricated through 3D printing from the corresponding dECM-MPs, enhancing the regeneration of the corresponding tissues in vivo. Especially, the realization of printability of highly rigid dECM-MPs confirms the universality, reliability and efficiency of the present strategy.