Development of Injectable Laponite-Based Materials with Promoted Osteogenic Differentiation Capacity

In this study, rod like hydroxyapatite (HAp) with a length of 25—35 nm and a width of 10—20 nm was synthesized by chemical precipitation method. Then the HAp was doped in situ into the nano-disk osteogenic Laponite (LP) matrix. A type of injectable composite with high bioactivity was prepared by a single-step ultrasonic mixing method by leveraging Laponite’s good water solubility and in situ gelation property. The prepared gel material showed good injectability and thixotropic properties. A comparative study was conducted between pure LP injectable material (LIM) and LP/HAp injectable material (LHIM). The results of X-Ray Energy Spectrum showed that the HAp in the LHIM was well dispersed. The results of Scanning Electron Microscope (SEM) showed that the introduction of HAp increased the surface roughness of LHIM compared with LIM. The results of rabbit bone marrow mesenchymal stem cells (rBMSCs) in vitro showed that both LHIM and LIM had good cytocompatibility, and more rBMSCs adhered to the surface of LHIM in one day. The results of transwell showed that compared with LIM, LHIM could further improve the migration ability of rBMSCs. The results of osteogenic activity in vitro showed that LHIM can increase rBMSCs alkaline phosphatase (ALP), Runt-related transcription factor 2 (Runx2) and osteocalcin (OCN) activity. LHIM has the advantages of simple preparation, rapid gelation, no cross-linking agent, easy storage and good osteogenic activity. Therefore, LHIM is expected to be a bone repair material for clinical use. The current study provides a potential therapeutic tool for bone repair and regeneration.