3D printed hybrid scaffolds for bone regeneration using calcium methoxyethoxide as a calcium source

Introduction: Hybrids consist of inorganic and organic co-networks that are indistinguishable above the nanoscale, which can lead to unprecedented combinations of properties, such as high toughness and controlled degradation. Methods: We present 3D printed bioactive hybrid scaffolds for bone regeneration, produced by incorporating calcium into our Bouncy Bioglass, using calcium methoxyethoxide (CME) as the calcium precursor. SiO2-CaOCME/PTHF/PCL-diCOOH hybrid inks for additive manufacturing (Direct Ink Writing) were optimised for synergy of mechanical properties and open interconnected pore channels. Results and Discussion: Adding calcium improved printability. Changing calcium content (5, 10, 20, 30, and 40 mol.%) of the SiO2-CaOCME/PTHF/PCL-diCOOH hybrids affected printability and mechanical properties of the lattice-like scaffolds. Hybrids containing 30 mol.% calcium in the inorganic network (70S30C(CME)-CL) printed with 500 mu m channels and 100 mu m strut size achieved the highest strength (0.90 +/- 0.23 MPa) and modulus of toughness (0.22 +/- 0.04 MPa). These values were higher than Ca-free SiO2/PTHF/PCL-diCOOH hybrids (0.36 +/- 0.14 MPa strength and 0.06 +/- 0.01 MPa toughness modulus). Over a period of 90 days of immersion in simulated body fluid (SBF), the 70S30C(CME)-CL hybrids also kept a stable strain to failure (similar to 30 %) and formed hydroxycarbonate apatite within three days. The extracts released by the 70S30C(CME)-CL hybrids in growth medium did not cause cytotoxic effects on human bone marrow stromal cells over 24 h of culture.

Automated summary

This study introduces a new bioactive hybrid scaffold for bone regeneration. By incorporating calcium ions into a flexible bioglass and using 3D printing technology, the scaffold exhibited excellent mechanical properties and biocompatibility.