Magnetoprint: sizing and magnetically-assisted 3d printing of smart metamaterial hydrogels for tissue engineering
3D printing (3DP) technology plays a pivotal role in the biofabrication of engineered tissues which are useful towards several clinical, diagnostic and research applications. Of the different 3DP approaches, extrusion bioprinting (EBp) is the most widely used, for it is cost effective and allows rapid fabrication of physiological scale tissues with controlled placement of different types of encapsulated cells and biomaterials. However, the poor resolution (> 200 µm) of most EBp approaches limits the topographical cues necessary to impart anisotropic cell (avg. ϕ = 20 µm) and extracellular matrix organization within the tissues. Moreover, most tissue engineering approaches do not meet the nutritional requirements of the cells within thick tissues, and utilize static cultures which do not recapitulate the physiological growth conditions. Due to these reasons, the engineered tissues fail to biomimic native tissue properties. The proposed MagnetoPrint process aims to achieve biomimicry via a synergy of chemistry, biology, electromechanical systems design, structural mechanics and multiphysics modeling. First, cell-laden hydrogels are synthesized which could be sized into microstrands (avg. ϕ = 40 µm) during printing, that could impart the relevant anisotropic characteristics. Second, ferromagnetic particles are incorporated within distinct compartments inside the hydrogels to facilitate the deformation of printed tissue in the presence of external magnetic fields. Control of the domain orientations of the magnetic particles is used to impart auxetic properties, to further support nutrient transport and tissue maturation, which is also verified by computational modeling. Third, a complex muscle/tendon interface is printed and matured under the relevant exercising conditions to demonstrate the effectiveness of the project. The process, with its unprecedented features, represents significant progress in the advanced scalable manufacturing of biomimetic engineered tissues.