Shedding light on 3D printing: Printing photo-crosslinkable constructs for tissue engineering

Abstract

3D printing has emerged as a pivotal fabrication technique for preparing scaffolds for engineering tissues and tissue models. Among different 3D printing platforms, photo-crosslinking-based 3D printing techniques like digital light processing and stereolithography have become most popular as they enable the construction of complex architecture with improved spatial resolution, reliable pattern fidelity, and high printing speed. In addition, by selecting appropriate ink combinations or modulating the photo-crosslinking printing parameters (e.g., the types or concentrations of photoinitiators and crosslinkers, light exposure time or intensity, as well as the 3D printing techniques used), the structures and properties (e.g., swelling and mechanical properties) of the resultant printed scaffolds can be finely tailored to meet the practical application requirements. Here, recent advances on the promising development of photo-crosslinkable materials for 3D printing with a focus on their biomedical applications for repairing damaged organs and developing in vitro tissue models are reviewed. Firstly, an overview of commonly used photo-crosslinkable materials, as well as insights on how the printing outcomes of these materials can be improved are provided. Then, the diverse regulation strategies of the photo-polymerization process and the 3D printing parameters to improve the performances of the printed structures are summarized. The existing challenges and future directions are finally discussed from the technical and application perspectives of photo-crosslinking-based 3D printing.