Field, E. H.; Ratcliffe, J.; Johnson, C. J.; Binger, K. J.; Reynolds, N.

There is a pressing need for new biomaterials that are printable, stiff and highly biocompatible. This is primarily due to the inverse relationship between the printability and viscosity of hydrogels. Cell-laden, printable, rigid biomaterials are needed for replicating stiffer tissues such as cartilage in regenerative medicine, modelling the fibrosis of tissue and cancer microenvironments, as well as in non-cellular research fields such as biosensors. Here, we have designed a hybrid material compromised of self-assembled Fmoc-FF peptide assemblies dispersed throughout a sodium alginate matrix. The resultant hybrid bioink has a stiffness up to 10 times greater than sodium alginate alone but remains highly printable, even when laden with high concentrations of cells. In addition, the thixotropic self-assembled peptide assemblies gave the hybrid bioinks highly desirable self-healing capabilities. The choice of solvent used to initially dissolve the peptides made significant differences to both the physical properties and the biocompatibility of the bioinks, with the best performing able to support the growth of encapsulated macrophages over 5 days. Our developed hybrid materials allow the bioprinting of materials previously considered too stiff to extrude without causing shear induced cytotoxicity with applications in tissue engineering and biosensing.