Physicochemical and physiological requirements of the bioink. Physicochemical properties are related to the printability by the viscosity and macromolecular structure of the material. The printed construct should also allow for diffusion, relating the printed architecture to the cytocompatibility. The physiological activity is related to cytocompatibility by the degradation products, the behavior under physiological conditions, and the biological activity (e.g. cell binding motifs). The final product, the cell-loaded construct, should seamlessly combine these qualities.