Design and characterization of advanced micro- and nano-fiber reinforced hydrogels for 3D bioprinting of anisotropic tissues

Natural complexity arises from the organization of individual elements into larger systems. This hierarchy, found at different size scales, contributes to the overall properties and functionalities of these systems. Another important concept in nature is anisotropy, which refers to the directional dependence of physical properties. Anisotropic structures are commonly found in tissues of the human body, providing specific physical properties in preferred orientations. This study aimed to develop a new bioink for 3D bioprinting that replicates the alignment of native anisotropic tissues. A composite bioink using alginate and modified gelatin was optimized as the hydrogel matrix, along with various micro/nanofillers. The reinforced bioink design consists of fabricating and characterizing the micro/nanofibers, optimizing the hydrogel component, and incorporating the micro/nanofillers into the hydrogel. The resulting composite bioink was tested for stability, rheological properties and compatibility with the bioprinting process. The bioink was successfully used for 3D bioprinting, obtaining good shape fidelity and alignment of the microfibers. This advanced microfiber-reinforced bioink has the potential to create in vitro models that closely resemble the structure and organization of natural tissues.