Smart biomaterials in the dimensional revolution of bioprinting: From 2D to 6D for advanced biomedical applications

The dimensions of biomaterials have significantly impacted their applications in biomedical and personalized medicine. These advancements have enabled the design of complex, multifunctional structures with biomimetic properties, with implications for many biomedical applications. Graphene and MXenes, as 2D biomaterials with high mechanical, electrical, and biocompatible properties, play a crucial role in biosensing, microscopy, and regenerative medicine. Three-dimensional (3D) bioprinting, with high precision and scalability, enables the creation of complex biomedical structures, allowing researchers to develop implants, tissues, and therapeutic devices with specific spatial organization. The inclusion of time as the fourth dimension led to the emergence of 4D bioprinting, enabling the creation of dynamically active, stimuli-responsive biomaterials. Advanced concepts in 5D and 6D bioprinting further added structural complexity and functional integration, creating biomaterials that mimic nature and advanced biological behaviors. These advanced, higher-dimensional bioprinting technologies have opened new horizons for innovation in tissue engineering, drug delivery, surgical planning, and diagnostics. This review provides a comprehensive overview of recent progress in bioprinting, particularly the integration of smart materials and the evolution from 2D to 6D bioprinting, which could transform personalized healthcare and enable novel therapeutic solutions.