Ca2+-supplying black phosphorus-based scaffolds fabricated with microfluidic technology for osteogenesis

Abstract

Effective osteogenesis remains a challenge in the treatment of bone defects. The emergence of artificial bone scaffolds provides an attractive solution. In this work, a new biomineralization strategy is proposed to facilitate osteogenesis through sustaining supply of nutrients including phosphorus (P), calcium (Ca), and silicon (Si). We developed black phosphorus (BP)-based, three-dimensional nanocomposite fibrous scaffolds via microfluidic technology to provide a wealth of essential ions for bone defect treatment. The fibrous scaffolds were fabricated from 3D poly (l-lactic acid) (PLLA) nanofibers (3D NFs), BP nanosheets, and hydroxyapatite (HA)-porous SiO₂ nanoparticles. The 3D BP@HA NFs possess three advantages: i) stably connected pores allow the easy entrance of bone marrow-derived mesenchymal stem cells (BMSCs) into the interior of the 3D fibrous scaffolds for bone repair and osteogenesis; ii) plentiful nutrients in the NFs strongly improve osteogenic differentiation in the bone repair area; iii) the photothermal effect of fibrous scaffolds promotes the release of elements necessary for bone formation, thus achieving accelerated osteogenesis. Both in vitro and <i>in vivo</i> results demonstrated that the 3D BP@HA NFs, with the assistance of NIR laser, exhibited good performance in promoting bone regeneration. Furthermore, microfluidic technology makes it possible to obtain high-quality 3D BP@HA NFs with low costs, rapid processing, high throughput and mass production, greatly improving the prospects for clinical application. This is also the first BP-based bone scaffold platform that can self-supply Ca²⁺, which may be the blessedness for older patients with bone defects or patients with damaged bones as a result of calcium loss.