3D printing: prospects and challenges

Regenerative medicine is an emergent multidisciplinary field that aims to significantly improve tissue repair or restoration, thus focusing on tissue engineering (TE) in regenerative medicine is inevitable. TE has created a useful ground in which biomaterials science witnessed a huge jump in improving diagnosis and treatment during recent years. TE brings together relevant knowledge from physical sciences, molecular engineering, biotechnology, and medicine toward ameliorated regrowing of the damaged tissue when the body is not able to completely heal itself. three-dimensional (3D) printing comes as a branch of TE technologies, allowing the synthesis of 3D constructs that provide key physiological environments for cell growing. In addition, nanoengineered systems hold tremendous potential in regenerative medicine, as their properties can be fine-tuned to promote tighter communication between cells and implantable materials. In Subchapter 4.1, intelligent biomaterials, 3D printing-based technologies, and nanosystems for imaging and drug delivery are presented and discussed, with special emphasis to their current applications toward a sounding impact in regenerative medicine. While the use and applicability of nanotechnology is swiftly expanding in several areas of biomedical engineering, its utility has not been fully realized in 3D bioprinting. Nanostructured materials seem to have enormous potential in bioprinting, as even a small fraction of nanoparticle loading can remarkably enrich the printability of bioinks without affecting the viability of the encapsulated cells, and in many cases enhancing overall cell behavior, such as differentiation, proliferation, electrical conductivity, and so on. Additionally, nanomaterials enable easy surface modification with specific biochemical factors or cellular ligands to improve cell adhesion, signaling, and specific cell functions. Subchapter 4.2 provides a general introduction to the background and motivation of using nanomaterials in tissue engineering and regenerative medicine by means of 3D bioprinting. We provide an overview of the current literature on some of the frequently employed nanomaterials in developing hybrid bioinks for 3D bioprinting applications, and describe a range of bioink properties that can be enhanced by the inclusion of specific nanoparticles. In addition, we discuss potential toxicity issues that may arise from the use of nanofilled bioinks, while advocating thorough screening of nanomaterials to avoid undesirable or toxic side effects.