3D bioprinting and photocrosslinking: emerging strategies & future perspectives

3D bioprinting has enabled the creation of biomimetic tissue constructs for regenerative medicine and in vitro model systems. Large-scale production of 3D structures at the micron-scale resolution is achieved through bioprinting using custom bioinks. Stability and 3D construct compliance play an important role in offering cells with biomechanical cues that regulate their behavior and enable in vivo implantation. Various crosslinking strategies are developed to stabilize the 3D printed structures and new methodologies are constantly being evaluated to overcome the limitations of the existing methods. Photo-crosslinking has emerged as a simple and elegant technique that offers precise control over the spatiotemporal gelation of bioinks during bioprinting. This article summarizes the use of photo-crosslinking agents and methodology towards optimizing 3D constructs for specific biomedical applications. The article also takes into account various bioinks and photo-crosslinkers in creating stable 3D printed structures that offer bioactivity with desirable physicochemical properties. The current challenges of 3D bioprinting and new directions that can advance the field in its wide applicability to create 3D tissue models to study diseases and organ transplantation are also summarized.