A Bilayer Membrane Doped with Struvite Nanowires for Guided Bone Regeneration

Guided bone regeneration (GBR) therapy demonstrates a prominent curative effect on the management of craniomaxillofacial (CMF) bone defects. In this study, a GBR membrane consisting of a microporous layer and a struvite-nanowire-doped fibrous layer is constructed via non-solvent induced phase separation, followed by an electrospinning procedure to treat critical-sized calvarial defects. The microporous layer shows selective permeability for excluding the rapid-growing non-osteogenic tissues and potential wound stabilization. The nanowire-like struvite is synthesized as the deliverable therapeutic agent within the fibrous layer to facilitate bone regeneration. Such a membrane displays a well-developed heterogeneous architecture, satisfactory mechanical performance, and long-lasting characteristics. The in vitro biological evaluation reveals that apart from being a strong barrier, the bilayer struvite-laden membrane can actively promote cellular adhesion, proliferation, and osteogenic differentiation. Consequently, the multifunctional struvite-doped membranes are applied to treat 5 mm-sized bilateral calvarial defects in rats, resulting in overall improved healing outcomes compared with the untreated or the struvite-free membrane-treated group, which is characterized by enhanced osteogenesis and significantly increased new bone formation. The encouraging preclinical results reveal the great potential of the bilayer struvite-doped membrane as a clinical GBR device for augmenting large-area CMF bone reconstruction.