PNNL

Abstract

Regenerative bone engineering has potential to replace autogenous bone grafts; however, no synthetic, commercially available material fully meets the design criteria: 1) mechanical strength maintained throughout resorption, 2) osteoconductivity and osteoinductivity without growth factors, and 3) patient-specific geometries. Nanocarbons, including graphenic materials, have recently been incorporated with additive manufacturing to improve matrix osteogenic properties. Yet, the osteogenic properties of unmodified graphenic materials are limited and incorporation into three-dimensional (3D) matrices is constrained to low wt.%. Recently, the functionalized graphenic material, calcium phosphate graphene (CaPG), demonstrated promise in fulfilling two criteria: the graphenic backbone provides strength and osteoconductivity while the calcium phosphate chains impart intrinsic osteoinductivity. But until now, processing into customizable geometries was challenging. This work presents porous, customizable, mechanically robust, 3D printed (3DP) matrices of 90% CaPG that induce bone regeneration in a mouse calvarial defect. 3DP-CaPG offers an osteoconductive surface with osteoinductive properties to promote bone regeneration through osteoblast activity. Histological analysis shows tartrate-resistant acid phosphatase positive staining around the matrix struts in a manner suggesting potential osteoclast activity. Resorption of the CaPG matrix was observed and presented no local cytotoxicity or systemic toxicity. 3DP-CaPG matrices represent an enabling advancement towards a clinically viable, synthetic bone regeneration matrix.