DLP printing of hydrogel/calcium phosphate composites for the treatment of bone defects

In this work, biocomposites based on hydrogels filled with calcium phosphates were fabricated using DLP method of 3D printing for the treatment of bone defects. The possibility to tune the functional properties of hydrogels such as degradation, swelling, and mechanical behavior by using a mixture of monomers with different functionality and different calcium phosphates was shown. Mechanical properties, photopolymerization, swelling behavior, and microstructure of hydrogels based on a mixture of poly(ethylene glycol) methacrylate/poly(ethylene glycol) diacrylate (PEGMA/PEGDA) monomers with different composition were studied. It was found that the usage of α-tricalcium phosphate (α-TCP) powder as a filler for hydrogels allowed to increase the filler fraction up to 60 ​wt% in comparison with octacalcium phosphate (OCP) and brushite (10 ​wt%) without significant thickening of photosuspension for DLP printing. Finally, the main parameters of DLP printing for biocomposites based on PEGMA/PEGDA hydrogels were found, and the macroporous biocomposite filled with 60 ​wt% α-TCP with gyroid structure was obtained. • The macroporus composite based on PEGMA/PEGDA hydrogels filled with 60 ​wt.% α-TCP with gyroid structure was obtained. • The possibility to tune the degradation of hydrogels by using a mixture of monomers with different functionality was shown. • Varying the ratio of PEGMA/PEGDA allows correcting the low degradation rate and swelling ability of PEGDA hydrogels. • Usage of α-TCP for filling hydrogels allowed to increase the filler fraction in comparison with OCP and brushite.