From light to life: Photocrosslinkable bioinks and their role in 3D bioprinting for shaping future regenerative medicine

Tissue engineering and regenerative medicine have created significant opportunities for designing new approaches to restore, substitute, or regenerate injured tissues and organs. Among the emerging technologies supporting this advancement, three-dimensional (3D) bioprinting has gained particular attention due to its capability to produce tailored constructs that replicate many of the biological and mechanical characteristics of natural tissues. Within this field, photocrosslinkable bioinks have gained significant attention as a viable and versatile option. By leveraging light-induced reactions, these bioinks enable rapid and spatially controlled gelation, providing tunable mechanical characteristics and superior print fidelity for fabricating functional tissue-like structures. This review presents a comprehensive overview of the principles and mechanisms underlying photocrosslinkable bioinks, focusing on key photocrosslinking strategies, alongside the role of photoinitiators in modulating these processes. It further delves into the classification of photocrosslinkable bioinks, encompassing synthetic polymers, natural hydrogels, and cell-laden formulations, and discusses essential formulation parameters. The review also evaluates the advantages and limitations of these bioinks, supported by case studies that illustrate their various biomedical applications. Ultimately, current challenges are addressed alongside future directions and technological innovations poised to advance clinical translation in this rapidly evolving field.