Three-dimensional (3D) printing is an additive manufacturing process that enables the precise production of complex structures, layer by layer, with functional properties. The development of new biomaterials that could be used to produce 3D scaffolds for tissue regeneration and/or drug release systems, is nowadays a developing research field. [1,2] Biocompatibility and non-toxic properties are fundamental requirements to select the polymers to use as base matrices. However, using exclusively biopolymers often leads to poor mechanical properties. To overcome this challenge, inorganic reinforcing compounds, as hydroxyapatite, can be applied. This strategy improves both the structural and functional properties of the printed scaffolds.

In this research, an extrusion-based 3D printing was used, with a computer-controlled system, that enabled continuous deposition of the proposed bioblends, along the x-y-z axis. The studied formulations consisted of sodium alginate (5, 7.5 and 10%):hydroxyapatite (0, 2.5 and 5%) mixtures, dopped with 0.1% sulfanilamide. After printing, chemical crosslinking was performed by immersion in an aqueous calcium chloride solution.

The results showed that the addition of hidroxiapatite was fundamental to achieve a printable blend, once increase the viscosity. Mechanical properties were also enhanced and alginate and hydroxyapatite concentrations had influence on the drug release profile.

The feasibility of creating network-like three-dimensional structures using sulfanilamide-doped alginate–hydroxyapatite formulations was confirmed in our investigation. The drug release process performed better with lower alginate concentrations and more successfully with the addition of hydroxyapatite. These results show that these composite systems are promising for developing better biomaterials for use in tissue regeneration and drug delivery systems.